215 pubblicazioni classificate nel seguente modo:

Synthesis and characterization of PLD CoFe thin films as a function of composition and deposition conditions
Proceedings of Magnet 2015, Bologna (IT)
Autore/i: Peddis, D.; Barucca, Gianni; Varvaro, G.; Testa, A. M.; Mengucci, Paolo; Agostinelli, E.; Laureti, S.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251533

Thermal and spatial confinement effects in exchange coupled IrMn/NiFe dot arrays
Proceedings of ICM-2015, Barcelona (ES)
Autore/i: Spizzo, F.; Bonfiglioli, E.; Tamisari, M.; Gerardino, A.; Barucca, Gianni; Notargiacomo, A.; Chinni, F.; Del Bianco, L.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251535

Biomedical alloys produced by direct metal laser sintering
Multinational Conference on Microscopy 2015 (MCM 2015)
Autore/i: Mengucci, Paolo; Barucca, Gianni; Gatto, A.; Bassoli, E.; Iuliano, L.; Rutkowski, B.
Luogo di pubblicazione: Eger
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Direct Metal Laser Sintering (DMLS) is an advanced manufacturing technology based on layer-by-layer deposition for the production of complex functional mechanical parts. In the DMLS technology, a solid-state laser controlled by a scanning system sinters successive layers of a metal powder in accordance to the previously realized CAD/CAM model. In the biomedical field, DMLS is a promising technology for prosthetic applications where complex geometries, low volumes and strong individualization are required. Co- and Ti-based alloys are extensively used in biomedical applications due to their mechanical properties and biocompatibiliy. In this study, a Co-Cr-Mo composition suitable for biomedical applications and a Ti-6Al-4V alloy were produced by the DMLS technology. In order to study the structure stability of the alloys, samples were submitted to thermal treatments.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/235064

Flux Pinning in Y- and Ag-Doped MgB2
ADVANCES IN MATERIALS PHYSICS AND CHEMISTRY
Autore/i: Dyson, Jack; Rinaldi, Daniele; Barucca, Gianni; Albertini, Gianni; Sprio, Simone; Tampieri, Anna
Classificazione: 1 Contributo su Rivista
Abstract: High temperature superconductor research is presently concentrated upon the flux pinning properties of the Abrikosov lattice of the mixed-mode superconducting phase. The temperature thermal fluctuations, current and magnetic field unpin the flux vortices and so cause electromagnetic resistivity in high temperature superconductors. Materials with higher vortex pinning exhibit less resistivity and are more attractive for industrial uses. In the present article, we measured and correlated the pinning flux energy barrier, determined by AC magnetic measurements, and transmission electron microscopy measurements to the critical current Jc in Yttrium- and Silver-doped MgB2 superconductors. The energy of the flux vortex was evaluated as a function of the magnetic field. The energy barrier curves suggest an optimal doping level to occur in doped materials. This result only depends on the optimal size and distribution of precipitates, and not on their chemical composition. The energy barriers have been compared with that of undoped MgB2 in literature.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/228103

Highly Textured FeCo Thin Films Deposited by Low Temperature Pulsed Laser Deposition
ACS APPLIED MATERIALS & INTERFACES
Autore/i: Varvaro, Gaspare; Peddis, Davide; Barucca, Gianni; Mengucci, Paolo; Rodionova, Valeria; Chichay, Ksenia; Testa, Alberto Maria; Agostinelli, Elisabetta; Laureti, Sara
Classificazione: 1 Contributo su Rivista
Abstract: The effect of the deposition temperature (Tdep) on the crystallographic orientation of pulsed laser-deposited FeCo/MgO(100) thin film was determined by means of X-ray reflectivity and high resolution trasmission electron microscopy analysis and was correlated with the magnetic anisotropy properties measured by angle dependent hysteresis loops. Highly textured films with a bcc structure and very smooth surface were obtained even at room temperature, the film being [100] and [110] oriented, at Tdep = 25 °C and 150 °C, respectively. The cubic symmetry is reflected in the angular dependence of remanent magnetization, showing a 4-fold character, whose in-plane distribution is consistent with the different crystallographic orientations of the films. The high structural quality, even at room temperature, is reflected in a high value of the saturation magnetization and low coercivity, matching the requirements for technological applications.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/230133

Hydrogen storage properties of Pd-doped thermally oxidized single wall carbon nanohorns.
JOURNAL OF ALLOYS AND COMPOUNDS
Autore/i: Giasafaki, D.; Charalambopoulou, G.; Tampaxis, C. h.; Gattia, D. Mirabile; Montone, A.; Barucca, Gianni; Steriotis, T. h. .
Classificazione: 1 Contributo su Rivista
Abstract: Single wall carbon nanohorns as well as their thermally oxidized derivatives were decorated with Pd nanoparticles and their H2 sorption performance was examined at 298 K up to 20 bar. The specific surface area of the nanohorns was increased through air oxidation, while both the thermal treatment and the metal doping led to the enhancement of the H2 uptake. The higher uptake of the hybrid materials could not be attributed only to the additive effect of the carbon support and Pd content suggesting the existence of a cooperative mechanism between the metal particles and the carbon surface. This weak chemisorption process was found to be fully reversible after mild heating; still, its contribution to the overall H2 uptake was not found to be of great significance.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/221916

Structural characterization of biomedical Co-Cr-Mo components produced by Direct Metal Laser Sintering.
MATERIALS SCIENCE AND ENGINEERING. C, BIOMIMETIC MATERIALS, SENSORS AND SYSTEMS
Autore/i: Barucca, Gianni; Santecchia, Eleonora; Majni, Giuseppe; Girardin, Emmanuelle; Elena, Bassoli; Lucia, Denti; Andrea, Gatto; Luca, Iuliano; Tomasz, Moskalewicz; Mengucci, Paolo
Classificazione: 1 Contributo su Rivista
Abstract: Direct metal laser sintering (DMLS) is a technique to manufacture complex functional mechanical parts from a computer-aided design (CAD) model. Usually, the mechanical components produced by this procedure show higher residual porosity and poorer mechanical properties than those obtained by conventional manufacturing techniques. In this work, a Co-Cr-Mo alloy produced by DMLS with a composition suitable for biomedical applications was submitted to hardness measurements and structural characterization. The alloy showed a hardness value remarkably higher than those commonly obtained for the same cast or wrought alloys. In order to clarify the origin of this unexpected result, the sample microstructure was investigated by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and energy dispersive microanalysis (EDX). For the first time, a homogeneous microstructure comprised of an intricate network of thin ε (hcp)-lamellae distributed inside a γ (fcc) phase was observed. The ε-lamellae grown on the {111}γ planes limit the dislocation slip inside the γ (fcc) phase, causing the measured hardness increase. The results suggest possible innovative applications of the DMLS technique to the production of mechanical parts in the medical and dental fields.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/221915

Magnetic exchange coupling in IrMn/NiFe nanostructures: From the continuous film to dot arrays.
PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS
Autore/i: F., Spizzo; E., Bonfiglioli; M., Tamisari; A., Gerardino; Barucca, Gianni; A., Notargiacomo; F., Chinni; L., Del Bianco
Classificazione: 1 Contributo su Rivista
Abstract: A comprehensive description of the exchange bias phenomenon in an antiferromagnetic/ferromagnetic IrMn(10 nm)/NiFe(5 nm) continuous film and in arrays of square dots with different sizes (1000, 500, and 300 nm) is presented, which elucidates the temperature dependence of the exchange field Hex and coercivity HC, in conjunction with spatial confinement effects. To achieve this goal, samples prepared by electron beam lithography and lift-off using dc sputtering were subjected to structural investigations by electron microscopy techniques and to magnetic study, through SQUID and magneto-optic magnetometry measurements coupled to micromagnetic calculations. In particular, we have observed that at T=300K Hex decreases by reducing the size of the dots and it is absent in the smallest ones, whereas the opposite trend is visible at T=10K (Hex∼1140Oe in the dots of 300nm). The exchange bias mechanism and its thermal evolution have been explained through an exhaustive phenomenological model, which joins spatial confinement effects with other crucial items concerning the pinning antiferromagnetic phase: the magnetothermal stability of the nanograins forming the IrMn layer (mean size ∼10nm), assumed as essentially noninteracting from the magnetic point of view; the proven existence of a structurally disordered IrMn region at the interface between the NiFe phase and the bulk of the IrMn layer, with a magnetic glassy nature; and the stabilization of a low-temperature (T<100K) frozen collective regime of the IrMn interfacial spins, implying the appearance of a length of magnetic correlation among them.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/221917

Synthesis of nanogranular Fe3O4/biomimetic hydroxyapatite for potential applications in nanomedicine: structural and magnetic characterization
MATERIALS RESEARCH EXPRESS
Autore/i: Del Bianco, L; Lesci, Ig; Fracasso, G; Barucca, Gianni; Spizzo, F; Tamisari, M; Scotti, R; Ciocca, L.
Classificazione: 1 Contributo su Rivista
Abstract: We realized the synthesis of a novel nanogranular system consisting of magnetite nanoparticles embedded in biomimetic carbonate hydroxyapatite(HA), for prospective uses in bone tissue engineering. An original two-step method was implemented: in the first step, magnetite nanoparticles are prepared by refluxing an aqueous solution of Fe(SO4) and Fe2(SO4)3 in an excess of tetrabutilammonium hydroxide acting as surfactant; then,the magnetite nanoparticles are coated witha Ca(OH)2 layer,to induce the growth of HA directly on their surface, by reaction of Ca(OH)2 with HPO4 2−.Two nanogranular samples were collected with magnetite content∼0.8and∼4wt%. The magnetite nanoparticles and the composite material were investigated by x-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy.These analyses provided information on the structure of the nanoparticles(meansize∼6nm)and revealed the presence of surface hydroxylgroups, which promoted the subsequent growth of the HA phase, featuring a nanocrystalline lamellar structure.The magnetic study,by a superconducting quantum interference device magnetometer, has shown that both the as-prepared and the HA-coated magnetite nanoparticles are superparamagnetic at T=300K, but the magnetization relaxation process is dominated by dipolar magnetic interactions of comparable strength.In the three samples, a collective frozen magnetic regime is established belowT∼20K. These results indicate that the magnetite nanoparticles tend to form agglomerates in the as-prepared state,which are not substantially altered by the HA growth, coherently with the creation of electrostatic hydrogen bonds among the surface hydroxyl groups.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233911

Structural, mechanical and light yield characterisation of heat treated LYSO:Ce single crystals for medical imaging applications.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT
Autore/i: Mengucci, Paolo; G., André; E., Auffray; Barucca, Gianni; C., Cecchi; R., Chipaux; A., Cousson; Davi', Fabrizio; N., Di Vara; Rinaldi, Daniele; Santecchia, Eleonora
Classificazione: 1 Contributo su Rivista
Abstract: Five single crystals of cerium-doped lutetium yttrium oxyorthosilicate (LYSO:Ce) grown by the Czochralski method were submitted to structural characterization by X-ray (XRD) and neutron (ND) diffraction, scanning (SEM) and transmission (TEM) electron microscopy and energy dispersive microanalysis (EDS).The Ultimate Tensile Strength (UTS), the Young Modulus (YM) and the Light Yield (LY) of the samples were also measured in order to correlate the mechanical and the optical behavior of the crystals with the characteristics of their microstructure. Two of the samples analysed were also heat treated at 300°C for 10 h to evidence possible variations induced by the temperature in the optical and mechanical response of the crystals. Results showed that the mean compositional variations evidenced by the structural analyses do not affect the mechanical and optical behavior of the samples. On the contrary, the therma treatment could induce the formation of coherent spherical particles (size 10 to 15 nm), not uniformly distributed inside the sample, that strongly reduce the UTS and YM values, but it does not affect the optical response of the crystal. This latter result was attributed to the low value o fthe heating temperature (300 °C) that is not sufficiently high to induce annealing of the oxygen vacancies traps that are responsible of the deterioration of the scintillation properties of the LYSO:Ce crystals. This study was carried out in the framework of the Crystal Clear Collaboration (CCC).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/221515

Ledge-type Co/L10-FePt exchange-coupled composites
Proceedings of ICM-2015, Barcelona (ES)
Autore/i: Speliotis, T. H.; Giannopoulos, G.; Niarchos, D.; Li, W. F.; Hadjipanayis, G.; Barucca, Gianni; Agostinelli, E.; Fiorani, D.; Laureti, S.; Peddis, D.; Testa, A. M.; Varvaro, G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251534

Biomedical metal alloys produced by direct metal laser sintering
Proceedings of EUROMAT 2015, Warsaw (PL)
Autore/i: Barucca, Gianni; Bassoli, E.; Denti, L.; Fiori, Fabrizio; Gatto, A.; Girardin, Emmanuelle; Mengucci, Paolo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251538

Method and device for detecting the water pollution
Autore/i: Barucca, Gianni; Mengucci, Paolo; Tiberi, Emanuele
Classificazione: 6 Brevetti
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/249954

Single step plasma deposition of platinum-fluorocarbon nanocomposite films as electrocatalysts of interest for micro fuel cells technology.
PLASMA PROCESSES AND POLYMERS
Autore/i: Antonella, Milella; Fabio, Palumbo; Elena, Dilonardo; Barucca, Gianni; Pinalysa, Cosma; Francesco, Fracassi
Classificazione: 1 Contributo su Rivista
Abstract: In this paper, we present a one step plasma based approach for the deposition of Pt-fluorocarbon nanocomposite films as electrocatalysts in hydrogen-based micro fuel cells. Results show that the chemical and morphological structure of the film can be tuned by controlling the power delivered to the plasma, and the gas feed composition. Platinum is included in the film in metallic form and its content can be continuously varied from a few atomic percent to 86%. The metal is embedded in the film as crystalline nanoclusters of size below 10 nm, uniformly distributed across the sample. Film catalytic activity, in terms of hydrogen oxidation reaction, has been tested by cyclovoltammetry and it increases with the Pt loading, with a maximum specific electrochemical surface area of 94cm(2) center dot mg(-1), for film deposited on flat glassy carbon.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/221914

DNA damage and repair following in vitro exposure to two different forms of titanium dioxide nanoparticles on trout erythrocyte
ENVIRONMENTAL TOXICOLOGY
Autore/i: Durairaj, Sekar; Maria Letizia, Falcioni; Barucca, Gianni; Giancarlo, Falcioni
Classificazione: 1 Contributo su Rivista
Abstract: TiO2 has been widely used to promote organic compounds degradation on waste aqueous solution, however, data on TiO2 nanotoxicity to aquatic life are still limited. In this in vitro study, we compare the toxicity of two different families of TiO2 nanoparticles on erythrocytes from Oncorhynchus mykiss trout. The crystal structure of the two TiO2 nanoparticles was analyzed by XRD and the results indicated that one sample is composed of TiO2 in the anatase crystal phase, while the other sample contains a mixture of both the anatase and the rutile forms of TiO2 in a 2:8 ratio. Further characterization of the two families of TiO2 nanoparticles was determined by SEM high resolution images and BET technique. The toxicity results indicate that both TiO2 nanoparticles increase the hemolysis rate in a dose dependent way (1.6, 3.2, 4.8 lg mL21) but they do not influence superoxide anion production due to NADH addition measured by chemiluminescence. Moreover, TiO2 nanoparticles (4.8 lg mL21) induce DNA damage and the entity of the damage is independent from the type of TiO2 nanoparticles used. Modified comet assay (Endo III and Fpg) shows that TiO2 oxidizes not only purine but also pyrimidine bases. In our experimental conditions, the exposure to TiO2 nanoparticles does not affect the DNA repair system functionality. The data obtained contribute to better characterize the aqueous environmental risks linked to TiO2 nanoparticles exposure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/115064

Kinetic behaviour of a metal-polymer composite suitable for hydrogen storage applications
INTERNATIONAL JOURNAL OF NANOTECHNOLOGY
Autore/i: Santecchia, E.; Barucca, Gianni; Majni, Giuseppe; Mengucci, Paolo; Checchetto, R.; Carotenuto, G.
Classificazione: 1 Contributo su Rivista
Abstract: Hydrogen storage in composite materials is a feasible way to overcome the main drawbacks of the metal hydride systems. In the present paper, we report on the hydrogenation properties of three polydimethylsiloxane (PDMS)–palladium composite samples with different content of metallic fraction (5, 15, 50 in wt.%). Hydrogenation tests in different conditions of temperature and pressure were performed using a Sievert’s type apparatus, while the microstructure of the samples was characterised by means of scanning electron microscopy observations and X-ray diffraction measurements. Results show that the hydrogen storage capacity is inversely proportional to the metallic content in the composite samples.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/179340

Microstructural investigation of magnetic CoCrPt:SiO2 films.
Proceedings of Multinational Conference (MC) 2013, Regensburg (D), Part 1
Autore/i: Santecchia, Eleonora; Barucca, Gianni; Mengucci, Paolo; Varvaro, G.; Testa, A. M.; Agostinelli, E.; Springer, F.; Brombacher, C.; Albrecht, M.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251531

Dispositivo e Metodo per Rilevare l’Inquinamento delle Acque
Autore/i: Barucca, Gianni; Mengucci, Paolo; Tiberi, Emanuele
Classificazione: 6 Brevetti
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/249937

Hydrogen storage behaviour of Pd-polymer composites.
Proceedings of Multinational Conference (MC) 2013, Regensburg (D), Part 1
Autore/i: Mengucci, Paolo; Barucca, Gianni; Carotenuto, G.; Checchetto, R.; DI CRISTOFORO, Adriano; Miotello, A.; Santecchia, Eleonora
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251528

Silicon nanostructures produced by self-masked plasma etching.
Proceedings of Multinational Conference (MC) 2013, Regensburg (D), Part 1
Autore/i: Barucca, Gianni; Santecchia, Eleonora; Mengucci, Paolo; Tiberi, Emanuele; Di Mundo, R.; D'Agostino, R.; F., Palumbo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251530

Direct metal laser sintering of a biocompatible Co-Cr-Mo alloy.
Proceedings of Multinational Conference (MC) 2013, Regensburg (D), Part 1
Autore/i: Girardin, Emmanuelle; Barucca, Gianni; Santecchia, Eleonora; Mengucci, Paolo; Moskalewicz, T.; Gatto, A.; Bassoli, E.; Denti, L.; Iuliano, L.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251532

Characterization of cerium-doped LYSO scintillating crystals
Proceedings of Microscopy Conference (MC) 2013, Regensburg (D), Part 1
Autore/i: Santecchia, Eleonora; Barucca, Gianni; DI CRISTOFORO, Adriano; Rinaldi, Daniele; Tiberi, Emanuele; Mengucci, Paolo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/251529

Magnesium growth in magnesium deuteride thin films during deuterium desorption
JOURNAL OF ALLOYS AND COMPOUNDS
Autore/i: Checchetto, R.; Miotello, A.; Mengucci, Paolo; Barucca, Gianni
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/155111

Study Of Microstructure And Magnetization Reversal Mechanism In Granular CoCrPt:SiO2 Films Of Variable Thickness
MATERIALS CHEMISTRY AND PHYSICS
Autore/i: G., Varvaro; A. M., Testa; E., Agostinelli; D., Fiorani; S., Laureti; F., Springer; C., Brombacher; M., Albrecht; L., Del Bianco; Barucca, Gianni; Mengucci, Paolo; Rinaldi, Daniele
Classificazione: 1 Contributo su Rivista
Abstract: The effect of the thickness and microstructural features on the switching behaviour of granular CoCrPt:SiO2 films with perpendicular magnetic anisotropy was investigated. TEM plane view and cross section analysis indicate that, while the very first layers grow as uniform nanograins in close contact, the growth proceeds by formation of well-defined CoCrPt columnar islands (7 nm average size) separated by the silicon oxide, the distance among the islands remaining roughly constant along the whole thickness. The relation between such non-uniform microstructure and the magnetization reversal mechanism at room temperature was investigated by performing hysteresis loops at variable angle as well as time dependent measurements by using a vector vibrating sample magnetometer. Numerical micromagnetic simulations of the hysteresis loops have been carried out to support the description of the experimental observations. The results showed a coexistence of coherent and incoherent reversal processes, the former being more and more pronounced with increasing the magnetic layer thickness, consistently with the microstructural investigations.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/105863

Comparative toxicity of CuO nanoparticles and CuSO4 in rainbow trout
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
Autore/i: Gloria, Isani; Maria Letizia, Falcioni; Barucca, Gianni; Durairaj, Sekar; Giulia, Andreani; Emilio, Carpenè; Giancarlo, Falcioni
Classificazione: 1 Contributo su Rivista
Abstract: This study compared the toxicity and accumulation of two different Cu compounds, CuO nanoparticles (NPs) and soluble CuSO4, in erythrocytes and different tissues in rainbow trout (Oncorhynchus mykiss). The crystal structure of CuO NP analysed by XRD indicates that the NP are Tenorite, a monoclinic CuO. The in vitro toxicity results indicate that both Cu compounds increase the haemolysis rate in a dose-dependent way, but the effect was reduced treating cells with CuO NP. Moreover, both Cu compounds induce DNA damage and the entity of the damage, similarly to haemolysis, was more marked in cells treated with CuSO4. In vivo results, obtained after intraperitoneal injection, showed that Cu concentrations were significantly higher in gills (p<0.0001), kidney (p=0.007) and liver (p<0.05) of exposed fish with a significant increase in plasma Cu concentration 15h after CuSO4 treatment. Cu concentrations were significantly higher in fish exposed to CuSO4 than CuO in kidney (p<0.05) and gills (p<0.0001). Significant DNA damage with respect to controls was detected only when Cu was injected as CuSO4. The present data could serve to evaluate environmental Cu toxicity in fish depending on Cu speciation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/115062

On the “growth” of nano-structures on c-silicon in self-masked plasma etching processes.
PLASMA PROCESSES AND POLYMERS
Autore/i: Di Mundo, R.; Palumbo, F.; Barucca, Gianni; Sabato, G.; D’Agostino, R.
Classificazione: 1 Contributo su Rivista
Abstract: Plasma etching is emerging as reliable top-down self-masked approach for nanotexturing on a wafer-scale the surface of crystalline silicon. Differently sized and shaped nano-bumps can be obtained as a function of plasma parameters and, accordingly, different optical and optoelectronic effects have been already reported. In this work, we utilize a combination of techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, field emission gun scanning electron microscopy, in order to enlighten on structure, composition, and topography of these nano-objects. The results indicate that they present a composite structure, with a crystalline conic base and an amorphous extension with inclusion of metallic nano-crystals. These and other evidences suggest that the structures are partly formed by the sculpting action typically ascribed to the etching process, partly due to a deposition of amorphous composite matter, likely aggregated by a catalytic action of the metal particles.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/155113

Effects of sorption cycles on the microstructure of Mg-Nb films
Proceedings of 10th Multinational Congress on Microscopy
Autore/i: Santecchia, Eleonora; Barucca, Gianni; Gobbi, Luigi; Mengucci, Paolo; R., Checchetto
Editore: Kennedy srl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/199302

Single step plasma deposition of hydrocarbon thin films containing Pt nanoclusters for fuel cells applications
Proceedings of 10th Multinational Congress on Microscopy
Autore/i: Barucca, Gianni; Santecchia, E.; Mengucci, Paolo; Milella, A.; Palumbo, F.
Editore: Kennedy srl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/69904

Precipitation sequence in a QE22 magnesium alloy.
MICROSCOPIE
Autore/i: Barucca, Gianni; DI CRISTOFORO, Adriano; Lussana, D.; Mengucci, Paolo; Santecchia, Eleonora
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/76460

Formation and evolution of the hardening precipitates in a Mg-Y-Nd alloy
ACTA MATERIALIA
Autore/i: Barucca, Gianni; Ferragut, R.; Fiori, Fabrizio; Lussana, D.; Mengucci, Paolo; Moia, F.; Riontino, G.
Classificazione: 1 Contributo su Rivista
Abstract: The formation and evolution of hardening precipitates in a Mg-Y-Nd (WE43) alloy during artificial ageing at 150 and 210 °C is followed by small angle X-ray scattering (SAXS) measurements, Vickers microhardness tests and transmission electron microscopy (TEM) observations. A quantitative description of the alloy studied during the early and advanced stages of the precipitation sequence is presented. In situ SAXS evolution at 210 °C of the size, volume fraction and number density of the subnanometer and nanometer particles that evolve in the β″ phase was obtained. TEM and microhardness results indicate that the hardening mechanism is based on β″ transformation of pre-precipitates and their growth at 150 °C, while at 210 °C hardening is mainly associated with β″ → β′ transformation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/54588

Structure modification of Mg-Nb films under hydrogen sorption cycles
JOURNAL OF ALLOYS AND COMPOUNDS
Autore/i: Mengucci, Paolo; Barucca, Gianni; Majni, Giuseppe; Bazzanella, N.; Checchetto, R.; Miotello, A.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/54697

Modified TiO2 particles differentially affect human skin fibroblasts exposed to UVA light.
FREE RADICAL BIOLOGY & MEDICINE
Autore/i: Tiano, Luca; Armeni, Tatiana; Venditti, E; Barucca, Gianni; Mincarelli, L; Damiani, Elisabetta
Classificazione: 1 Contributo su Rivista
Abstract: Free Radic Biol Med. 2010 Aug 1;49(3):408-15. Epub 2010 May 5. Modified TiO(2) particles differentially affect human skin fibroblasts exposed to UVA light. Tiano L, Armeni T, Venditti E, Barucca G, Mincarelli L, Damiani E. Source Dipartimento di Biochimica, Biologia e Genetica, , Università Politecnica delle Marche, I-60131 Ancona, Italy. Abstract Numerous sunscreens contain titanium dioxide (TiO(2)) because of its ability to reflect, scatter, and absorb UV radiation, thus preventing sunlight-related skin disorders. Since TiO(2) is well known to generate reactive oxygen species (ROS) under photoexcitation, it is chemically modified when used in sunscreens. In the present study, five modified TiO(2) particles, specifically developed and marketed for sunscreens, were tested using different in vitro models, including cultured human skin fibroblasts (HuDe), to investigate their possible photocatalytic effects following UVA exposure. The results obtained show that the type of modification and crystal form determine their ability to (a) induce photobleaching of the DPPH radical, (b) photodegrade deoxyribose, (c) reduce cell viability, (d) increase/decrease DNA damage, and (e) increase/decrease intracellular ROS. This research concludes that some modified TiO(2) particles still retain photocatalytic activity under the experimental conditions employed, especially those in which the anatase crystal form of TiO(2) is present. The penetration of TiO(2) nanosized particles into the viable epidermis of skin is still under debate; thus, the results presented here contribute to gaining further knowledge on the potential effects of TiO(2) particles at the cellular level, in the worst possible case that they do penetrate. Copyright 2010 Elsevier Inc. All rights reserved. PMID: 20450973 [PubMed - indexed for MEDLINE]
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/75468

Plasma deposited Pt-containing hydrocarbon thin films as electrocatalysts for PEM fuel cell.
JOURNAL OF MATERIALS CHEMISTRY
Autore/i: Dilonardo, E; Milella, A; Palumbo, F; Thery, J; Martin, S; Barucca, Gianni; Mengucci, Paolo; D'Agostino, R; Fracassi, F.
Editore: Royal Society of Chemistry:Thomas Graham House, Science Park, Cambridge CB4 0WF United Kingdom:011 44 1223 432360, EMAIL: sales@rsc.org, INTERNET: http://www.rsc.org, http://www.chensoc.org, Fax: 011 44 1223 423429
Classificazione: 1 Contributo su Rivista
Abstract: High performance electrocatalytic hydrocarbon thin films containing Pt nano-clusters are deposited by simultaneous plasma polymerization of ethylene and sputtering of a Pt target. The proposed synthetic approach largely simplifies the PEMFC electrocatalyst fabrication process with respect to conventional methods. The deposition of the hydrocarbon matrix provides the mechanical support and electronic continuity, ensuring a uniform metal dispersion, avoiding Pt nanoparticle agglomeration. The Pt catalyst is dispersed as small vertically stacked clusters with size less than 10 nm in columnar thin (250-500 nm) films. PEMFC testing with plasma deposited 500 nm thick film and 0.513 mg cm-2 Pt load as anodic electrocatalyst led to a maximum reproducible power density as high as 300 mW cm-2. © 2010 The Royal Society of Chemistry.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/41114

Hardening Phases Evolution in the QE22 Magnesium Alloy.
Proceedings of MC 2009.
Autore/i: Barucca, Gianni; A., DI CRISTOFORO; L., Gobbi; D., Lussana; Mengucci, Paolo; G., Riontino
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/46533

Phase transformations in QE22 Mg alloy
ACTA MATERIALIA
Autore/i: Barucca, Gianni; Ferragut, R; Lussana, D; Mengucci, Paolo; Moia, F; Riontino, G.
Classificazione: 1 Contributo su Rivista
Abstract: The precipitation sequence in a QE22 Mg alloy is followed by differential scanning calorimetry, microhardness, electrical resistivity, positron annihilation spectroscopy and transmission electron microscopy (TEM) observations, after different thermal treatments. The decomposition of the supersaturated solid solution occurs via the formation of nanosized coherent structures (GP zones) followed by the co-precipitation of two metastable phases responsible for the peak ageing condition. The stable phase (Mg, Ag)12Nd appears at the highest annealing times, leading to over-ageing and hardness reduction. TEM observations provide information on the crystallographic structure of the forming phases, allowing some inconsistencies present in the literature to be clarified. Activation energies are derived from both calorimetric and resistometric measurements at different scanning rates.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53265

Structure evolution of EV31 Mg alloy.
JOURNAL OF ALLOYS AND COMPOUNDS
Autore/i: G., Riontino; D., Lussana; M., Massazza; Barucca, Gianni; Mengucci, Paolo; R., Ferragut
Classificazione: 1 Contributo su Rivista
Abstract: Structure modifications and precipitation hardening of EV31 Mg alloy have been monitored by calorimetric measurements (DSC), TEM observations and positron annihilation spectroscopy (PAS). At the early stages of precipitation DSC measurements andTEMobservations evidenced the formation of a phase, while the presence of an intermediate is supported by positron data. Overageing is correlated to the formation of an incoherent 1 phase, which transforms in situ into the equilibrium precipitate.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52223

A novel thermal treatment on Mg-4.2Y-2.3Nd-0.6Zr (WE43) alloy.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
Autore/i: G., Riontino; M., Massazza; D., Lussana; Mengucci, Paolo; Barucca, Gianni; R., Ferragut
Classificazione: 1 Contributo su Rivista
Abstract: A double-stage thermal treatment has been adopted on a Mg-Y-Nd-Zr (WE43) alloy, following suggestions of a previous calorimetric investigation. A secondary precipitation is claimed to occur at a temperature as low as 150 °C after a preliminary precipitation at 210 °C, with the effect of enhancing the hardness increase and reducing the annealing times.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53471

Structure evolution of a WE43 Mg alloy submitted to different thermal treatments.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
Autore/i: Mengucci, Paolo; Barucca, Gianni; G., Riontino; D., Lussana; M., Massazza; R., Ferragut; E., HASSAN ALY
Classificazione: 1 Contributo su Rivista
Abstract: The structure evolution of the WE43 Mg alloy during different thermal treatments is studied by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and positron annihilation spectroscopy (PAS). Isothermal annealings at different temperatures are made, with the aim to correlate the alloy's structure with its hardness response and to compare these treatments to the standard industrial T6 one (16 h at 250 °C). The highest hardening effect is obtained with a treatment at 210 °C with the formation of both β″ and β′ phases. A residual amount of solute atoms into the matrix after each thermal treatment promotes the renucleation of β″ and β′. The standard T6 treatment mainly leads to the precipitation of the β′ phase, while the thermal treatment at 280 °C essentially promotes the formation of the equilibrium β phase.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52729

Evolution of Hardening Precipitates in a WE43 Magnesium Alloy.
Proceedings of 8th Multinational Congress on Microscopy.
Autore/i: Mengucci, Paolo; Barucca, Gianni; A., DI CRISTOFORO; D., Lussana; M., Massazza
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/46592

Morphological and structural characterization of CrSi2 nanometric films deposited by laser ablation.
APPLIED SURFACE SCIENCE
Autore/i: Caricato, A. P.; Leggieri, G; Luches, A; Romano, F; Barucca, Gianni; Mengucci, Paolo; Mulenko, S. A.
Classificazione: 1 Contributo su Rivista
Abstract: The structure and morphology of chromium disilicide (CrSi2) nanometric films grown on 〈1 0 0〉 silicon substrates both at room temperature (RT) and at 740 K by pulsed laser ablation are reported. A pure CrSi2 crystal target was ablated with a KrF excimer laser in vacuum (∼3 × 10-5 Pa). Morphological and structural properties of the deposited films were investigated using Rutherford backscattering spectrometry (RBS), grazing incidence X-ray diffraction (GID), X-ray reflectivity (XRR), scanning (SEM) and transmission electron microscopy (TEM). From RBS analysis, the films' thickness resulted of ∼40 nm. This value is in agreement with the value obtained from XRR and TEM analysis (∼42 and ∼38 nm, respectively). The films' composition, as inferred from Rutherford Universal Manipulation Program simulation of experimental spectra, is close to stoichiometric CrSi2. GID analysis showed that the film deposited at 740 K is composed only by the CrSi2 phase. The RT deposited sample is amorphous, while GID and TEM analyses evidenced that the film deposited at 740 K is poorly crystallised. The RT deposited film exhibited a metallic behaviour, while that one deposited at 740 K showed a semiconductor behaviour down to 227 K.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51420

Precipitation Hardening of the EV31 Magnesium Alloy.
Proceedings of 8th Multinational Congress on Microscopy.
Autore/i: Mengucci, Paolo; Barucca, Gianni; A., DI CRISTOFORO; D., Lussana; M., Massazza
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/46534

Hardening nanostructures in an AlZnMg alloy
PHILOSOPHICAL MAGAZINE
Autore/i: Dupasquier, A; Ferragut, R; Iglesias, M. M.; Massazza, M; Riontino, G; Mengucci, Paolo; Barucca, Gianni; Macchi, C. E.; Somoza, A.
Classificazione: 1 Contributo su Rivista
Abstract: The formation of nanoscale and sub-nanoscale solute aggregates (clusters, Guinier–Preston zones and precipitates) in an AlZnMg alloy (Al–2.1 at.% Zn–1.5 at.% Mg) has been followed by a combination of experimental techniques with the aim of correlating the properties of the aggregates with their thermal history. The choice of thermal treatments was guided by the results of mechanical and calorimetric characterizations, supported by transmission electron microscopy for the identification of the morphology of the aggregates. Positron annihilation spectroscopy (using two variants of this technique, coincidence Doppler broadening and lifetime spectroscopy) was adopted for determining the local chemistry in the proximity of open volume defects. The geometrical parameters of the distribution (size, volume fraction, numerical density of the solute aggregates) were obtained by small-angle X-ray scattering. The results of the investigation provide new information regarding: two families of vacancy-rich clusters formed during or immediately after quenching; Guinier–Preston zones formed at 95C after room-temperature pre-ageing; growth of 0 and phases at 150C; solute clusters formed at room-temperature in conditions of secondary ageing after preliminary heating at 150C.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51890

Kinetics of hydrogen absorption and desorption in magnesium: Role of the structure and of catalysts
Advanced Materials for Energy Conversion III: A Symposium in Honor of Drs. G. Sandrock, L. Schiapbach and S. Suda.
Autore/i: Bazzanella, N; Checchetto, R; Miotello, A; D'Acapito, F; Maurizio, C; Barucca, Gianni; Majni, Giuseppe; Mengucci, Paolo
Editore: TMS
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The hydrogen desorption kinetics of pure and Nb-doped magnesium hydride film samples was investigated by using a Sievert-type apparatus. The overall activation energy and the reaction order controlling desorption are (141±5) kJ mol-1H and n ≈ 4 for Mg hydride and (51±5) kJ mol-1 H and n ≈ 1 for Nb-doped (5% at) Mg hydride indicating that, in the doped sample, hydrogen desorption is controlled by the H migration in transformed h-Mg layers. Structural analysis performed by X-Ray Diffraction (XRD) and Extended X-Ray Absorption Fine Structure spectroscopy (EXAFS) show that the catalytic effect of the Nb dopant is connected with the formation of NbH0.89 nanoclusters dispersed in the Mg hydride matrix. It is suggested that the catalysis process is also connected to the presence of Mg-Nb hydride interfaces where the transfer of H atoms preferentially occurs by connecting h-Mg grains and by the role of the MgH2-NbH 0.89 interface as preferential site for the dissociation of the hydride phase.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53562

Structural Evolution on Thermal Treatments of EV31 Alloy
Proceedings of the 7th International Conference on Magnesium Alloys and Their Applications.
Autore/i: Massazza, M; Rontino, G; Lussana, D; Iozzia, A; Barucca, Gianni; DI CRISTOFORO, A; Ferragut, R; Doglione, R; Mengucci, Paolo
Editore: K.U. KAINER
Luogo di pubblicazione: WEINHEIM
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53520

Excimer pulsed laser deposition and annealing of YSZ nanometric films on Si substrates
APPLIED SURFACE SCIENCE
Autore/i: Caricato, A. P.; Barucca, Gianni; DI CRISTOFORO, A; Leggieri, G; Luches, A; Majni, Giuseppe; Martino, M; Mengucci, Paolo
Classificazione: 1 Contributo su Rivista
Abstract: We report experimental results obtained for electrical and structural characteristics of yttria-stabilised zirconia (YSZ) thin films deposited by pulsed laser deposition (PLD) on Si substrates at room temperature. Some samples were submitted to thermal treatments in different ambient atmospheres (vacuum, N2 and O2) at a moderate temperature. The effects of thermal treatments on the film electrical properties were studied by C–Vand I–V measurements. Structural characteristics were obtained by X-ray diffraction (XRD), X-ray reflectivity (XRR) and transmission electron microscopy (TEM) analyses. The as-deposited film was amorphous with an in-depth non-uniform density. The annealed films became polycrystalline with a more uniform density. The sample annealed in O2 was uniform over all the thickness. Electrical characterisation showed large hysteresis, high leakage current and positive charges trapped in the oxide in the as-deposited film. Post-deposition annealing, especially in O2 atmosphere, improved considerably the electrical properties of the films.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53186

Nb clusters formation in Nb-doped magnesium hydride
APPLIED PHYSICS LETTERS
Autore/i: R., Checchetto; N., Bazzanella; A., Miotello; C., Maurizio; F., Dacapito; Mengucci, Paolo; Barucca, Gianni; Majni, Giuseppe
Classificazione: 1 Contributo su Rivista
Abstract: Nb K-edge Extended X-ray Absorption Fine Structure spectroscopy (EXAFS), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) were used to analyse the Nb coordination and phase formation in Nb-doped (5 at. %) h-Mg film samples deposited by r.f. magnetron sputtering. Results show that the catalytic effect of the Nb doping in the H2 absorption and desorption kinetics is connected with the formation of Nb nano-clusters dispersed in the host matrix. The H2 desorption from b-MgH2 is favoured by the elastic stress produced by b-NbH0.89 clusters on the MgH2 matrix that reduces the stability of the hydride phase and by preferential paths in the nanocomposite hydride.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50846

Effects of annealing on the microstructure of yttria-stabilised zirconia thin films deposited by laser ablation.
THIN SOLID FILMS
Autore/i: Mengucci, Paolo; Barucca, Gianni; Caricato, A. P.; DI CRISTOFORO, A.; Leggieri, G.; Majni, Giuseppe; Luches, A.
Classificazione: 1 Contributo su Rivista
Abstract: In this paper the microstructural characterisation of yttria-stabilised zirconia (YSZ) thin films deposited by laser ablation is reported for the as-deposited sample as well as for samples submitted to thermal treatments in different atmospheres (vacuum, N2 and O2) at a moderate temperature (500 8C). Results obtained by different characterisation techniques such as grazing incidence X-ray diffraction, X-ray reflectivity and transmission electron microscopy evidenced the formation of the cubic YSZ phase after the annealing treatments. On the contrary, the asdeposited sample is amorphous with nanocrystals of the cubic YSZ phase dispersed inside. It also exhibits a difference between the density of the surface region and the region of the interface with the substrate. This latter effect has been attributed to the loss of oxygen atoms during the deposition. The annealing treatments are able to recover the density unhomogeneity present inside the as-deposited sample, the degree of recovering depends on the ambient atmosphere.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50071

Microstructure analysis on polycrystalline 3C–SiC thin films.
DIAMOND AND RELATED MATERIALS
Autore/i: C., Ricciardi; F., Giorgis; G., Fanchini; S., Musso; V., Ballarini; E., Bennici; Barucca, Gianni; A. M., Rossi
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: Polycrystalline 3C-SiC thin films grown by LPCVD on different substrates were characterized by vibrational and electronic spectroscopies and electron diffraction measurements aimed at studying the samples microstructure. Raman spectra evidence the coexistence of crystallites, whose size distribution depends on the deposition conditions, and of a disordered matrix. On the other side, IR reflectivity measurements show spectra which are strongly influenced by the surface morphology.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39181

Structural and magnetic properties of exchange-spring FeTaN/FeSm/FeTaN multilayers
SURFACE SCIENCE
Autore/i: G., Gubbiotti; P., Vavassori; G., Carlotti; M., Madami; Barucca, Gianni; Mengucci, Paolo; J., Weston; G., Zangari
Classificazione: 1 Contributo su Rivista
Abstract: The structural and magnetic properties of FeTaN/FeSm/FeTaN multilayers, deposited by dc magnetron sputtering, have been investigated as function of the alloy layers thickness. Structural and morphological characterizations, accomplished by transmission electron microscopy, X-ray reflectivity and grazing-incidence X-ray diffraction, account for a well-defined layered structure of the multilayers with a limited interface roughness. The magnetization reversal process is examined experimentally using magneto-optical Kerr vector magnetometry by measuring the longitudinal and transverse hysteresis loops. It is found that, for soft layer thickness above 3.2 nm, the magnetization reversal occurs via the formation of a stable exchange-spring state in which the magnetic moments of the outermost soft layer gradually rotates away from the unswitched underlying hard layer.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51204

Polycrystalline SiC growth and characterization
APPLIED SURFACE SCIENCE
Autore/i: C., Ricciardi; E., AIMO BOOT; F., Giorgis; P., Mandracci; U. M., Meotto; Barucca, Gianni
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: Growth of 3C-SiC on (100) Si wafers has been carried out by low pressure chemical vapor deposition (LPCVD), using a H(2) + SiH(4) + C(3)H(8) gas mixture at about 1000 degreesC. No carbonization layer was performed. Micro-Raman measurements yield the presence of microcrystalline SiC matrix, while neither carbon nor silicon clusterization in amorphous phase was detected with optimized deposition conditions. Transmission electron microscopy has been used to analyze the orientation of the films and the surface growth: the presence of voids and edge dislocations at the interface was revealed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39689

Effect of oxygen post-annealing on the magnetoresistance of highly epitaxial La0.7Ca0.3MnO3 thin films.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
Autore/i: A., DE SANTIS; Barucca, Gianni; F., Bobba; Caciuffo, ROBERTO GIOVANNI MARIA; K., Fröhlich; M., Pripko; A. M., Cucolo
Classificazione: 1 Contributo su Rivista
Abstract: Epitaxial La0.7Ca0.3MnO3 (LCMO) thin films have been deposited by high pressure DC sputtering technique on SrTiO3 substrates. As-grown films exhibit metal - insulator transition temperature (T-MI) with values ranging from 131 to 220 K. The maximum value of the magnetoresistance is of about - 77% in a magnetic field of 0.5 T for T-MI = 131 K. The same films, annealed in a pure oxygen atmosphere, exhibit transitions to a metallic state at temperatures ranging from 210 to 284 K. Transmission electron microscopy analyses show a coherent growth between film and substrate.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53083

Deposition of microcrystalline silicon-carbon alloys in low power regime
JOURNAL OF NON-CRYSTALLINE SOLIDS
Autore/i: G., Ambrosone; Barucca, Gianni; U., Coscia; S., Ferrero; S., Lettieri; P., Maddalena
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: Hydrogenated silicon-carbon films have been grown in a PECVD system over a wide range of RF power by silane+methane gas mixtures highly diluted in hydrogen. The effect of RF power on the properties of the deposited films has been explored. The RF power appears to control the transition from microcrystalline to amorphous phase. The increase in RF power modifies the hydrogenated microcrystalline silicon-carbon (μc-Si1-xC x:H) growth from columnar silicon crystals to crystallites uniformly dispersed in an amorphous matrix and enhances the carbon content in the films increasing their energy gap. μc-Si1-xCx:H samples with higher dark conductivity are deposited at lower RF power and those having carbon content x≥0.074 exhibit photoluminescence in the visible region at room temperature.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39692

Characterization of silicon carbide thin films grown on Si and SiO2 / Si substrates
MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY
Autore/i: P., Zanola; E., Bontempi; C., Ricciardi; Barucca, Gianni; L. E., Depero
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: Due to its outstanding electrical and mechanical properties, silicon carbide (SiC) is considered a leading semiconducting material for high temperature sensors. Since the piezoresistive effect in SiC is highly anisotropic and exhibits a dependence on the crystal orientation, the role of the substrate on the residual stress must be investigated. This paper presents the structural and morphological characterisation of polycrystalline 3C-SiC films using two-dimensional X-Ray Diffraction (XRD2) and Transmission Electron Microscopy (TEM) techniques. 3C-SiC thin films were grown on single crystalline Si and on SiO2/Si substrates under the same deposition conditions. The influence of the two substrates on the structural and microstructral properties of the films was investigated. By means of XRD2 technique, particular attention was devoted to the stress calculation and in particular to the stress release by the formation of extended defects.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39688

New insights on amorphous silicon-nitride microcavities
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
Autore/i: V., Ballarini; Barucca, Gianni; E., Bennici; C. F., Pirri; C., Ricciardi; E., Tresso; F., Giorgis
Editore: Amsterdam : North-Holland
Classificazione: 1 Contributo su Rivista
Abstract: All amorphous silicon-nitride planar optical microcavities operating in the visible range have been grown by plasma enhanced chemical vapor deposition. The luminescence intensity of the N-rich silicon-nitride layer from a microcavity with 6 period distributed Bragg reflectors (DBRs) is two order of magnitude higher than that of the luminescent layer without the cavity. Moreover, a strong directionality of the microcavities emission can be observed. Such results can be ascribed to the anisotropic optical density of states induced in the Fabry-Perot structure. The quality factors of the resonators are strictly correlated to the number of periods of the DBRs.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39695

Microstructures of Sputtered Oriented Si/CeO2 Bilayers YBa2Cu3O7-_/Si Integrated Microelectronics.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
Autore/i: A., Chiodoni; E., Mezzetti; D., Botta; L., Gozzelino; B., Minetti; C. F., Pirri; E., Tresso; C., Camerlingo; G., Tallarida; Barucca, Gianni; F., Fabbri
Editore: World Scientific Publishing Company:PO Box 128, Farrer Road, Singapore 912805 Singapore:011 65 6 4665775, EMAIL: journal@wspc.com.sg, INTERNET: http://www.wspc.com.sg, http://www.worldscinet.com, Fax: 011 65 6 4677667
Classificazione: 1 Contributo su Rivista
Abstract: In the framework of a research aimed to superconductor/semiconductor integrated electronics, we have grown a-axis oriented YBa2CU3O7-δ (YBCO) thin films on silicon (100) substrates with (111) oriented insulating buffer layers of cerium dioxide (CeO2), using magnetron sputtering deposition techniques. The properties of the cerium dioxide layer have been preliminary optimized by means of several layout and by monitoring the growing procedures through X-ray diffraction, AFM and TEM techniques. The lattice matching between CeO2 and YBCO resulted to be worsened by an amorphous thin SiO2 layer at the Si/CeO2 interface, that decouples the buffer orientation from the seed orientation. However, it was possible to grow a relatively thick, optimally textured layer of CeO2 without spurious orientations. The YBCO films deposited on top of this layer result preferentially aaxis oriented. The transition widths are very large, jet well controllable and reproducible. Some technological applications can be already envisaged.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39693

Characterization of polycrystalline SiC layers grown by ECR-PECVD for micro-electro-mechanical systems.
THIN SOLID FILMS
Autore/i: C., Ricciardi; E., Bennici; M., Cocuzza; P., Mandracci; D., Bich; V., Guglielmetti; Barucca, Gianni
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: Large area (up to 4 inch) polycrystalline 3C-SiC films have been deposited by electron cyclotron resonance chemical vapor deposition technique. Crystalline and non-crystalline substrates such as (1 0 0) Si wafers, thermally oxidized Si wafers and Al2O3 ceramic sheets have been used, maintaining the same deposition conditions. The structural and morphological properties of the films were analyzed by means of transmission electron microscopy and X-ray diffractometry, while surface morphology was characterized by atomic force microscopy. Preliminary results on technological processes for the realization of polycrystalline SiC based micro-electro-mechanical systems are reported.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39694

Electronic Phase separation in La0.85Sr0.15CoO3.
Proceedings of 6th Multinational Congress on Microscopy.
Autore/i: Barucca, Gianni; Mengucci, Paolo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/46584

Thin Films of YSZ Deposited by Laser Ablation.
Proceedings of 6th Multinational Congress on Microscopy.
Autore/i: Mengucci, Paolo; A., DI CRISTOFORO; Barucca, Gianni; A. P., Caricato; M., Martino; G., Leggieri
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/46585

YBCO-based multilayers for superconductor/semiconductor integrated electronics.
Proceedings of INFMeeting.
Autore/i: C., Camerlengo; A., Chiodoni; G., Ghigo; L., Gozzelino; E., Mezzetti; B., Minetti; C. F., Pirri; E., Tresso; M. G., Grimaldi; G., Tallarida; Barucca, Gianni; F., Fabbri
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49555

Coherent carbon nitride phases grown on Si substrates by reactive laser ablation
Recent research developments in applied physics
Autore/i: Mengucci, Paolo; Barucca, Gianni; G., Majni; A., DI CRISTOFORO; G., Legieri; M., Martino
Editore: Transworld Research Network
Luogo di pubblicazione: KERALA
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50474

Reactive pulsed laser ablation deposition of nitride thin films
Recent research developments in applied physics
Autore/i: G., Leggieri; A. P., Caricato; M., Fernandez; M., Martino; Mengucci, Paolo; Barucca, Gianni
Editore: Transworld research network
Luogo di pubblicazione: KERALA
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/41262

Growth and characterization of a-axis YBCO films on CeO2/Si substrates.
Proceedings of INFMeeting.
Autore/i: A., Chiodoni; R., Gerbaldo; L., Gozzelino; E., Mezzetti; B., Minetti; C. F., Pirri; E., Tresso; C., Camerlingo; M. G., Grimaldi; G., Tallarida; Barucca, Gianni; F., Fabbri
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49556

Buffer layers for YBCO on Si.
Proceedings of INFMeeting.
Autore/i: E., Tresso; A., Chiodoni; E., Mezzetti; G., Tallarida; M. G., Grimaldi; Barucca, Gianni; C., Camerlingo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/46586

Effects of copper doping in MgB2 superconductor
SOLID STATE COMMUNICATIONS
Autore/i: Tampieri, A.; Celotti, G.; Sprio, S.; Rinaldi, Daniele; Barucca, Gianni; Caciuffo, ROBERTO GIOVANNI MARIA
Classificazione: 1 Contributo su Rivista
Abstract: Magnesium diboride, recently discovered as superconductor, is extremely interesting in respect to pairing mechanisms and phonon-mediated superconductivity, but its transition temperature (39K) is decidedly too low for practical applications. A rush for substitutions started, intended to raise Tc and possibly maintain acceptable critical current density. The difficult introduction of Cu was attempted, through a complex procedure employing CuB24 instead of metallic Cu: owing to the tendency of Cu to form inter-metallic compounds with Mg, only a maximum of 3mol% of Cu was safely substituted to Mg in MgB2 lattice and a small parameters contraction proportional to Cu content was recorded. The results are a decrease in Tc of about 0.5 K, not far from that found with Al addition, whose reasons are discussed and interpreted in terms of holes doping.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50228

Intermixing at interfaces of Fe/W multilayers
MATERIALS SCIENCE AND ENGINEERING. C, BIOMIMETIC MATERIALS, SENSORS AND SYSTEMS
Autore/i: E., Majkova; S., Luby; M., Jergel; A., Anopchenko; Y., Chushkin; Barucca, Gianni; A., DI CRISTOFORO; Mengucci, Paolo; E., D'Anna; A., Luches; M., Martino; HSIN YI, Lee
Classificazione: 1 Contributo su Rivista
Abstract: The interface reactions in (1 nm Fe/x nm W) and (2 nm Fe/x mn W) multilayers (x = 1, 2, 5 and 7) with 5 or 10 periods in as-deposited state and under KrF laser irradiation with fluences, F 0.05-0.25 J cm(-2) and 1 or 10 pulses were studied by X-ray diffraction (XRD), grazing incidence (GI) XRD, X-ray reflectivity, GI X-ray diffuse scattering and cross-section transmission electron microscopy (XTEM). Structurally coherent layers along the [110] direction with bcc symmetry were found in as-deposited and irradiated samples. This coherency is affected by the lateral waviness of the interfaces. The layered structure persists up to F 0.25 J cm(-2) and 10 pulses. Under the laser treatment, both the interface roughness and mixing increase with increasing deposited energy and promoted bcc W grain growth is observed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51475

Electrical properties of high-mobility two-dimensional electron gases in Si/SiGe modulation-doped heterostructures grown on silicon-on-insulator substrates
MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY
Autore/i: L., DI GASPARE; G., Scappucci; E., Palange; K., Alfaramawi; F., Evangelisti; Barucca, Gianni; G., Majni
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: The growth of high-mobility modulation-doped Si/SiGe heterostructures on silicon-on-insulator (SOI) substrates is demonstrated. The structural and electrical properties of the samples are comparable with those of similar samples grown on standard Si substrates. Electron mobilities as high as 2800 cm2 V-1 s-1 at room temperature and 8.2×104 cm2 V-1 s-1 at 4 K are obtained.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39696

A new monoclinic carbon nitride phase grows coherently on Si (001) substrates.
Proceedings of 5th Multinational Congress on Electron Microscopy.
Autore/i: Barucca, Gianni; G., Majni; Mengucci, Paolo; G., Leggieri; M., Martino
Editore: RINTON PRESS, INC, 565 EDMUND TERRACE, PRINCETON, NJ 07652 USA
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49782

Microstructural characterization of SiC layers obtained by microwave-CVD.
Proceedings of 5th Multinational Congress on Electron Microscopy.
Autore/i: Barucca, Gianni; P., Mandracci; S., Ferrero; G., Cicero; F., Giorgis; C. F., Pirri
Editore: INTON PRESS, INC, 565 EDMUND TERRACE, PRINCETON, NJ 07652 USA
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49783

Fe/W multilayers irradiated by laser beams.
Proceedings of 5th Multinational Congress on Electron Microscopy.
Autore/i: Mengucci, Paolo; A., Dicristoforo; Barucca, Gianni; E., Majkova; S., Luby; M., Martino; A., Luches
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49784

Monoclinic carbon nitride phase coherently grown on Si(001) substrates
JOURNAL OF APPLIED PHYSICS
Autore/i: Barucca, Gianni; Majni, Giuseppe; Mengucci, Paolo; Leggieri, G.; Martino, M.
Classificazione: 1 Contributo su Rivista
Abstract: Carbon nitride films deposited on Si (001 ) substrates at room temperature by XeCl laser ablation of graphite targets in low pressure (1, 5, 10 and 50 Pa) N2 atmosphere at fluence of 12 J/cm2 (∼0.4 GW/cm2) have been investigated by x-ray diffraction and transmission electron microscopy in order to study the structure of the films. The results showed that the samples are constituted of a continuous amorphous film inside which microcrystals of a coherently grown CNx phase are dispersed. This phase is monoclinic with the following lattice parameters: a=b=0.384 nm, c =0.302 nm, α=y=90°, and β=96.5°. The CNx phase grows with the (001) plane coincident with the (001) plane of the Si substrate and with the [010]CNx direction parallel to the [110]Si one.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52429

Hetero-epitaxy of 3C-SiC by Electron Cyclotron Resonance-CVD technique.
APPLIED SURFACE SCIENCE
Autore/i: P., Mandracci; A., Chiodoni; G., Cicero; S., Ferrero; F., Giorgis; C. F., Pirri; Barucca, Gianni; L., Calcagno; G., Foti; P., Musumeci; R., Reitano
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: In this work we mainly report on the analysis of polycrystalline 3C-SiC films grown by electron cyclotron resonance-chemical vapor deposition (ECR-CVD) on 4in. (100) and (111) c-Si wafers, using a H2 + SiH4 + CH4 gas mixture at substrate temperatures in the range 930-1050°C. Structural properties of the films were analyzed by X-ray diffractometry, micro-Raman spectroscopy and transmission electron microscopy, while the elemental composition was determined by Rutherford backscattering (RBS) technique. Micro-Raman measurements performed on the SiC layers show a peak around 796cm-1 due to transversal optical phonons of the crystalline SiC matrix, while neither carbon clusterization in graphitic phase nor Si clusterization in amorphous phase was observed. TEM analyses show a polycrystalline columnar structure with lateral crystal dimensions ranging from 300 up to 1400Å. The crystals orientation is very close to that of (100) and (111) Si substrates, as revealed by X-ray and electron diffraction.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39698

Phase separation as origin of the magnetic anomalies in La0.85Sr0.15CoO3
JOURNAL OF APPLIED PHYSICS
Autore/i: J., Mira; J., Rivas; G., Baio; Barucca, Gianni; Caciuffo, ROBERTO GIOVANNI MARIA; Rinaldi, Daniele; D., Fiorani; M. A., SEÑARÌS RODRÌGUEZ
Classificazione: 1 Contributo su Rivista
Abstract: The dependence of the ac-magnetic susceptibility of La0.85Sr0.15CoO3 on the annealing temperature used during synthesis is addressed. Such dependence has been previously attributed to compositional inhomogeneities. Nevertheless, the presence of distinct phases with different chemical compositions is excluded after explorations by several techniques. Instead it is proposed that an electronic phase separation takes place in the material, whose state is changed after charge-carrier redistributions due to the thermal history of the samples, analogously to parent manganese-based perovskites.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52125

Structural properties of 3C-SiC layers grown on Si substrates by electron cyclotron resonance CVD technique.
Mat. Res. Soc. Symp. Proc.
Autore/i: F., Giorgis; A., Chiodoni; G., Cicero; S., Ferrero; P., Mandracci; C. F., Pirri; Barucca, Gianni; L., Calcagno; G., Foti; P., Musumeci; R., Reitano
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49785

Large area microcrystalline silicon films grown by ECR-CVD
THIN SOLID FILMS
Autore/i: S., Ferrero; P., Mandracci; G., Cicero; F., Giorgis; C. F., Pirri; Barucca, Gianni
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: We report on the structural, optical and electrical properties of undoped microcrystalline silicon films deposited by ECR-CVD technique. In detail, films with a crystallinity fraction larger than 60%, optical absorption spectra close to those of monocrystalline silicon, deposition rate higher than 1 angstrom/s and electron mobility of approximately 50 cm2/V s have been obtained at substrate temperatures ranging from 200 to 300 °C.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39921

Si/SiGe modulation-doped heterostructures grown on silicon-on-insulator substrates for high-mobility two-dimensional electron gases.
APPLIED PHYSICS LETTERS
Autore/i: L., DI GASPARE; K., Alfaramawi; F., Evangelisti; E., Palange; Barucca, Gianni; G., Majni
Editore: American Institute of Physics:2 Huntington Quadrangle, Suite 1NO1:Melville, NY 11747:(800)344-6902, (631)576-2287, EMAIL: subs@aip.org, INTERNET: http://www.aip.org, Fax: (516)349-9704
Classificazione: 1 Contributo su Rivista
Abstract: The growth of high-mobility modulation-doped Si/SiGe heterostructures on silicon-on-insulator substrates is demonstrated. The structural and electrical properties of the samples are reported to be comparable with those of similar samples grown on standard Si substrates. Electron mobilities as high as 2900cm2/Vs at room temperature and 8.2 × 104cm2/Vs at 4.2 K were obtained.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39870

Optical and structural properties of SiC layers grown by Electron Cyclotron Resonance CVD technique.
DIAMOND AND RELATED MATERIALS
Autore/i: F., Giorgis; A., Chiodoni; G., Cicero; S., Ferrero; P., Mandracci; Barucca, Gianni; R., Reitano; P., Musumeci; L., Calcagno; G., Foti
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: Large area microcrystalline and polycrystalline SiC thin films have been grown by electron cyclotron resonance CVD over (100) silicon wafers. The samples have been characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), micro-Raman and photo luminescence spectroscopy. Stoichiometric SiC films containing 3C-SiC crystals with orientation close to that of Si substrate and lateral grain dimension up to 1400 Å were obtained under suitable deposition conditions. They also exhibit blue photoluminescence at room temperature in the range of 400-450 nm with features dependent on their structure.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39920

Growth and characterization of SiC layers obtained by microwave-CVD
THIN SOLID FILMS
Autore/i: P., Mandracci; S., Ferrero; G., Cicero; F., Giorgis; C. F., Pirri; Barucca, Gianni; R., Reitano; P., Musumeci; L., Calcagno; G., Foti
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: Silicon carbide is a wide band gap semiconductor of interest for its application in many electronic devices. In recent years, a large research activity has been devoted to growth techniques for amorphous, polycrystalline or even epitaxial structures. In this paper, we have reported results on microcrystalline and polycrystalline SiC layers grown by high temperature ECR-CVD over 4″ (100) silicon wafer in SiH4+CH4 gas mixtures. The structure of the films has been investigated by X-ray diffractometry, micro-Raman spectroscopy and transmission electron microscopy (TEM). Stoichiometric SiC films containing a complete chemical order, 3C-SiC crystals with orientation close to that of Si substrate and lateral dimensions larger than 100 nm have been obtained.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39922

Coherent growth of a CNx phase on Si (100) substrates.
Atti del Congresso Nazionale di Fisica della Materia.
Autore/i: Barucca, Gianni; Majni, G; Mengucci, Paolo; Leggieri, G; Luches, A; Martino, M.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49210

2d electron gases in single SiGe/Si(100) heterostructures.
Atti del Congresso Nazionale di Fisica della Materia.
Autore/i: Digaspare, L; Palange, E; Fiorini, P; Scappucci, G; Evangelisti, F; Barucca, Gianni; Majni, G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49787

Electronic transport properties of SiGe alloys and heterostructures grown by MBE.
Atti del Congresso Nazionale di Fisica della Materia.
Autore/i: Pinto, N; Murri, R; Pasquali, C; Barucca, Gianni; Majni, G; Leggieri, G.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49786

Crystalline carbon nitride films coherently grown on Si(100) substrates by reactive pulsed laser ablation.
Conference on Lasers and Electro-Optics Europe - Technical Digest
Autore/i: Barucca, Gianni; Elia, L; Fernandez, M; Luches, A; Majni, G; Martino, M; Mengucci, Paolo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49209

Parametric studies of carbon nitride thin films deposited by reactive pulsed laser ablation.
Proceedings of SPIE - The International Society for Optical Engineering
Autore/i: Acquaviva, S; D'Anna, E; DE GIORGI, M. L.; Leggieri, G; Luches, A; Martino, M; Perrone, A; Zocco, A; Barucca, Gianni; Mengucci, Paolo
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49836

Phase separation, thermal history and magnetic behaviour of Sr doped LaCoO3
JOURNAL OF PHYSICS. CONDENSED MATTER
Autore/i: G., Baio; Barucca, Gianni; Caciuffo, ROBERTO GIOVANNI MARIA; Rinaldi, Daniele; J., Mira; J., Rivas; M. A., SEÑARÌS RODRIGUEZ; D., Fiorani
Classificazione: 1 Contributo su Rivista
Abstract: High-resolution transmission electron microscopy observations and magnetic ac susceptibility measurements have been carried out to study the changes in the magnetic properties of La1-xSrxCoO3 samples (x less than or equal to 0.3) processed at different annealing temperatures, ranging from 1273 to 1573 K. Although neutron diffraction excludes the coexistence of distinct phases with different chemical composition, room temperature micrographs taken along the [0, -1, 1] rhombohedral zone-axis show bright fringes of different widths, extending over regions with sizes ranging from 8 to 40 nm. These regions are detected in all the samples, whatever the Sr content or the annealing temperature T-a. However, their number depends strongly on the processing conditions and becomes smaller and smaller as T-a increases. The periodicity of the bright fringes cannot be accounted for, either by variations in the sample thickness or by crystallographic defects, but it can be simulated if the presence of aperiodically alternate Sr-rich and La-rich (0, 1, 1) planes is assumed. On the other hand, the susceptibility measurements show that the amount of ferromagnetic phase present in each specimen depends on its thermal history. This suggests that the segregation of a second electronic phase takes place, the nucleation of which is influenced by the spatial homogeneity of the dopant distribution.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53257

Normal and anomalous codeposition of Zn-Ni alloys from chloride bath
JOURNAL OF APPLIED ELECTROCHEMISTRY
Autore/i: Roventi, Gabriella; Fratesi, Romeo; R. A., DELLA GUARDIA; Barucca, Gianni
Classificazione: 1 Contributo su Rivista
Abstract: The codeposition of Zn-Ni alloys from chloride bath has been studied by means of potentiostatic electrodeposition in the potential range -700 to -1100 mV vs Ag/AgCl, where both normal and anomalous codeposition occurs. Deposition of alloys of different composition, morphology and structure, depending on the cathodic potential, was found. Analysis of the partial current densities showed that the production of nickel rich alloys in the potential range -700 to -900 mV is due to the underpotential reduction of zinc, driven by nickel ion discharge. Morphological and microstructural analyses showed that these alloys have the face-centred-cubic structure of nickel (alpha phase) and that the addition of zinc in the nickel lattice causes internal stresses in the deposits, which are prevalently amorphous. At potentials more negative than -910 mV, corresponding to the equilibrium potential of the zinc rich gamma phase deposition, the rate of deposition of the alpha phase decreases and the further increase in deposit zinc content leads to the formation of the gamma phase, with a decrease in internal stress. In this range of potential, zinc and nickel reduction can occur separately, according to their respective exchange current densities.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50971

Strain-driven morphology of Si1-xGex islands grown on Si (100).
MICRON
Autore/i: N., Pinto; R., Murri; R., Rinaldi; Barucca, Gianni
Editore: Elsevier Science Limited:Oxford Fulfillment Center, PO Box 800, Kidlington Oxford OX5 1DX United Kingdom:011 44 1865 843000, 011 44 1865 843699, EMAIL: asianfo@elsevier.com, tcb@elsevier.co.UK, INTERNET: http://www.elsevier.com, http://www.elsevier.com/locate/shpsa/, Fax: 011 44 1865 843010
Classificazione: 1 Contributo su Rivista
Abstract: A study has been carried out on the morphology and structure of three-dimensional (3D) SiGe islands grown by molecular beam epitaxy (MBE) on Si(100) substrates. Samples of Si1-xGex alloys have been prepared to investigate the effects either of the alloy composition or of the growth temperature. Atomic force microscopy (AFM) evidenced the growth of 3D islands and transmission electron microscopy (TEM) demonstrated netting layer growth on Si(100), independently on the deposition conditions. Energy dispersive spectroscopy (EDS) microanalyses carried out on cross-sections of large Si1-xGex islands with defects allowed a measurement of the Ge distribution in the islands. To the best of our knowledge, these have been the first experimental evidences of a composition change inside SiGe islands. The interpretation of the experimental results has been done in terms of strain-enhanced diffusion mechanisms both of the growing species (Si and Ge) and of small islands.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39925

Carbon nitride coherently grown on Si (111) substrates by pulsed laser irradiation.
Proceedings of SPIE - The International Society for Optical Engineering.
Autore/i: Barucca, Gianni; Majni, Giuseppe; Mengucci, Paolo; Leggieri, G; Luches, A; Martino, M; Perrone, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49835

a-SiN:H Multilayer versus bulk structure: a real improvement of radiative efficiency?
JOURNAL OF NON-CRYSTALLINE SOLIDS
Autore/i: R., Rizzoli; C., Summonte; P., Rava; Barucca, Gianni; A., Desalvo; F., Giorgis; C. F., Pirri
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: The radiative properties of a-Si(0.6)N(0.4):Hla-Si(3)N(4):H multilayer structures are studied and compared to those of homogeneous a-Si(1-x)N(x):K films with x in the range 0.35-0.60. Transmission electron microscopy (TEM) shows interface abruptness in the multilayers. The photoluminescence (PL) efficiency of the multilayer structures is up to an order of magnitude larger than that of the him having the composition of the well layers. This result cannot be explained by an interface alloying model. The peak emission energy increase with decreasing well layer thickness is simulated in terms of spatial and quantum confinement models. The latter, associated with a disorder increase, gives the best fit.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39924

A new carbon nitride phase coherently grown on Si(111).
Atti del Congresso Nazionale di Fisica della Materia.
Autore/i: Acquaviva, S; Barucca, Gianni; Leggieri, G; Luches, A; Majni, G; Martino, M; Mengucci, Paolo; Perrone, A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49212

A carbon nitride phase coherently grown on Si(111).
Proceedings of IV Multinational Congress on Electron Microscopy.
Autore/i: Barucca, Gianni; Mengucci, Paolo; G., Leggieri; M., Martino
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49211

Structural details and magnetic order of La1-xSrxCoO3 (x ≤ 0.3).
PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS
Autore/i: R., Caciuffo; Rinaldi, Daniele; Barucca, Gianni; J., Mira; J., Rivas; M. A., SEÑARÌS RODRÌGUEZ; P. G., Radaelli; D., Fiorani; J. B., Goodenough
Classificazione: 1 Contributo su Rivista
Abstract: The crystallographic structure and the magnetic order of the distorted perovskite La1-xSrxCoO3 (0.10≤x ≤0.30) has been studied by neutron diffraction, high-resolution electron microscopy, and magnetic-susceptibility measurements. The results give direct evidence for an inhomogeneous distribution of the Sr2+ ions and the segregation of the material into hole-rich ferromagnetic regions and a hole-poor semiconducting matrix at lower values of x. The holes introduced by Sr doping are attracted to the Sr2+ ions where they stabilize to lowest temperatures an intermediate-spin state at neighboring trivalent cobalt. The antibonding e electrons so stabilized increase the mean unit-cell volume and are delocalized over the cobalt atoms of the cluster where they couple the localized t5 configurations ferromagnetically. Long-range ferromagnetic order between clusters is realized even for Sr doping as low as x=0.10. The transition to a spin glass state is observed only for Sr concentrations smaller than 0.10. The volume of a hole-rich cluster grows in a magnetic field, and the origin of the large negative magnetoresistance observed near Tc for 0.15 ≤ x ≤ 0.25 appears to be due to a growth of the clusters to a percolation threshold. For x=0.30, the σ* band of the intermediate-spin state below Tc is at the threshold of a transition from itinerant to polaronic conduction and, above Tc, the system transforms smoothly to a cluster state.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52847

Effects of cobalt thin films on the a-Si crystallisation induced by excimer laser irradiation.
APPLIED SURFACE SCIENCE
Autore/i: Mengucci, Paolo; Barucca, Gianni; D'Anna, E.; Jergel, M.; Luby, S.; Majkova, E.; Martino, M.
Classificazione: 1 Contributo su Rivista
Abstract: In the present work, we report the results obtained by laser irradiation of a-Si/Co/SiO(2) and a-Si/SiO(2) samples in order to study the influence of the Co film on the a-Si crystallisation process. Both Co and a-Si layers were deposited by electron beam evaporation. Cobalt films of 0.5, 1 and 3 nm were deposited upon a 300 nm thick SiO(2) layer. The thickness of the a-Si layer was fixed at 200 nm. Samples were irradiated by a XeCl excimer laser under fluences of 0.40, 0.45 and 0.50 J cm(-2) and 1 or 10 number of pulses. Grazing incidence XRD and cross-sectional TEM were used for sample characterisation. Results showed the formation of CoSi(2) that, in general, considerably improves the crystallinity of the a-Si layer. In some cases, the presence of the CoSi(2) underlayer allowed the complete crystallisation of the a-Si layer even after the first laser pulse. Without CoSi(2), the same results were obtained only with a higher number of pulses.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51009

Intermixing in immiscible Co/Ag/Co trilayers under XeCl laser annealing
THIN SOLID FILMS
Autore/i: E., D'Anna; G., Leggieri; A., Luches; M., Martino; Majni, Giuseppe; Barucca, Gianni; Mengucci, Paolo; S., Luby; E., Majkova; M., Jergel
Classificazione: 1 Contributo su Rivista
Abstract: Co/Ag/Co trilayers were studied in order to confirm our previous results on the laser irradiation improvement of GMR ratio in immiscible Ag/Co multilayers (MLs). E-beam deposited samples were processed by XeCl excimer laser at the fluences F = 0.15, 0.2, 0.3 and 0.36 J/cm(2) with n = 1-100 pulses of 30 ns duration. The temperature versus time evolutions were computed for the first laser pulse. Samples were studied by grazing incidence XRD, RES and resistometry. From results it follows that grain boundary diffusion of Ag across Co layers going through even during short irradiation times, may be the explanation of GMR improvement via transformation of continuous ML into discontinuous one.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51545

Microstructural characterization and corrosion resistance of Ni-Zn-P alloys electrolessly deposited from a sulphate bath.
JOURNAL OF APPLIED ELECTROCHEMISTRY
Autore/i: M., Bouanani; F., Cherkaoui; Fratesi, Romeo; Roventi, Gabriella; Barucca, Gianni
Classificazione: 1 Contributo su Rivista
Abstract: Electroless Ni-Zn-P alloy coatings were obtained on an iron substrate from a sulfate bath at various pH values. The effects of changes in bath pH on alloy composition, morphology, microstructure and corrosion resistance were studied. Scanning electron microscopy was performed to observe the morphological change of the deposits with bath pH. Coating crystallinity was investigated by grazing incidence asymmetric Bragg X-ray diffraction and transmission electron microscopy. A transition from an amorphous to polycrystalline structure was observed on increasing the bath alkalinity, and thus decreasing the phosphorus content of the alloys. A single crystalline phase corresponding to face-centred-cubic nickel was identified in the alloys obtained from a strong alkaline solution. An increase in zinc percentage up to 23% in the deposits does not change the f.c.c. nickel crystalline structure. Corrosion potential and polarization resistance measurements indicated that the corrosion resistance of electroless Ni-Zn-P alloys depends strongly on the microstructure and chemical composition. The deposits obtained at pH 9.0-9.5 and with 11.4-12.5% zinc and 11.8-11.2% phosphorous exhibited the best corrosion resistance.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53226

Amorphous silicon crystallisation induced by CoSi2 interlayers under XeCl excimer laser irradiation.
Proceedings of IV Multinational Congress on Electron Microscopy
Autore/i: Mengucci, Paolo; Barucca, Gianni; S., Luby; A., Luches
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49208

Photoluminescence investigation of short period silicon-germanium heterostructures grown using molecular beam epitaxy
SURFACE SCIENCE
Autore/i: N., Pinto; F., Tombolini; R., Murri; M., DE CRESCENZI; M., Casalboni; Barucca, Gianni; Majni, Giuseppe
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39219

New carbon nitride phase coherently grown on Si (111)
JOURNAL OF APPLIED PHYSICS
Autore/i: Barucca, Gianni; Majni, Giuseppe; Mengucci, Paolo; Leggieri, G.; Luches, A.; Martino, M.; Perrone, A.
Classificazione: 1 Contributo su Rivista
Abstract: Carbon nitride films, deposited on Si(111) substrates at room temperature by XeCl laser ablation of graphite targets in low pressure (1, 5, 10, and 50 Pa) N2 atmosphere at the fluence of 12 J/cm2 (∼0.4 GW/cm2), have been submitted to accurate x-ray diffraction and transmission electron microscopy investigations in order to study the structure of the films. Results showed that the samples are constituted of a continuous amorphous film inside which microcrystals of a new coherently grown CNx phase are dispersed. This new phase has a triclinic crystallographic cell with lattice parameters a=b=0.384 nm, c=0.438±0.007 nm, α=110±1°, β=105±1°, and γ=120°. It coherently grows on the (111) Si plane with the following orientation relationships: (001)CNx ∥(111)Si, [100]CN ∥[1-10)]Si, and [010]CNx ∥[01-1)]Si.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52114

MBE Growth and characterization of SiGe Heterostructures.
Atti del Congresso Nazionale di Fisica della Materia.
Autore/i: N., Pinto; R., Murri; M., DE CRESCENZI; F., Tombolini; M., Casalboni; Barucca, Gianni; G., Majni
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49215

Thick pure Ge films for photodetectors.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY. B
Autore/i: F., Scarinci; M., Fiordelisi; R., Calarco; S., Lagomarsino; L., Colace; G., Masini; Barucca, Gianni; S. COFFA AND S., Spinella
Editore: Slack Incorporated:6900 Grove Road:Thorofare, NJ 08086:(800)257-8290, (856)848-1000, EMAIL: customerservice@slackinc.com, INTERNET: http://www.slackinc.com, Fax: (856)853-5991
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/40823

Carbon nitride films deposited by reactive laser ablation.
APPLIED SURFACE SCIENCE
Autore/i: M. L., DE GIORGI; G., Leggieri; A., Luches; M., Martino; A., Perrone; A., Zocco; Barucca, Gianni; G., Majni; E., Gyorgy; I. N., Mihailescu; M., Popescu
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: Carbon nitride films were deposited at 20, 250 and 500 degrees C on [111] Si substrates by XeCl laser ablation of graphite in low pressure (1-50 Pa) N(2) atmosphere at fluences of 12 and 16 J/cm(2). Different diagnostic techniques (SEM, TEM, RBS, XPS, XRD) were used to characterize the deposited films. Films resulted plane and well adhesive to their substrates. N/C atomic ratios up to 0.7 were inferred from RBS measurements in films deposited at 20 degrees C and 16 J/cm(2). Nitrogen concentration increases with increasing ambient pressure and laser fluence. The N 1s peak of the XPS spectra indicate two different bonding states of nitrogen atoms to C atoms, while the C 1s peak, apart from the two bonding states to nitrogen atoms, indicates one bonding state with regard to carbon atoms. XRD and TEM analyses point to an oriented microcrystalline structure of the films. Heating of the substrate results in a lower nitrogen concentration in respect of films deposited at 20 degrees C in otherwise identical experimental conditions. Optical emission studies of the laser plasma plume indicate a correlation between the emission intensity of the CN radicals in the plume and the nitrogen atom concentration in the films.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/40821

Reactive Laser Ablation Deposition of Carbon Nitride Thin Films.
VUOTO
Autore/i: G., Leggieri; A., Luches; M., Martino; A., Perrone; Barucca, Gianni; Mengucci, Paolo
Editore: Patron Editore:Via Badini 12, I 40050 Quarto Inferiore Bologna Italy:011 39 051 767003, EMAIL: abbonamenti@patroneditore.com, info@patroneditore.com, INTERNET: http://www.patroneditore.com, Fax: 011 39 051 768252
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/40824