Stefano Enzo
Università di Sassari, Dipartimento di Chimica e Farmacia, Department Member
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The high-solute concentration branch of the coherent miscibility gap for the AI-Be system has been determined by combining resistometric and SAXS results. The analysis of SAXS curves indicates that G.P. zones are platelets. a :shape that... more
The high-solute concentration branch of the coherent miscibility gap for the AI-Be system has been determined by combining resistometric and SAXS results. The analysis of SAXS curves indicates that G.P. zones are platelets. a :shape that is in agreement with anisotropic elasticity considerations.
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In this work we reveal the structure of a NaYO 2 compound solved from the X-ray diffraction powder pattern using the " ab-initio " structure solution approach. The compound turned out to be of trigonal structure, S. G. R-3m isomorphous... more
In this work we reveal the structure of a NaYO 2 compound solved from the X-ray diffraction powder pattern using the " ab-initio " structure solution approach. The compound turned out to be of trigonal structure, S. G. R-3m isomorphous with α-NaFeO 2 layered compound. The lattice parameters are a = 3.404 and c = 16.602 Å, respectively, the atoms being located in Wickoff sites (cba) for O, Na and Y, respectively, leading to a calculated density of 4.31 g/cm 3. The ordering of sodium and yttrium atoms into alternate (111) planes of the cubic close-packed oxygen lattice of NaYO 2 is very regular. The octahedra are slightly distorted, the positive deviation of the O z parameter from 0.25 elongates the NaO 6 octahedra while compressing the YO 6 octahedra. Actually the Na-O and Y-O bond distances are 2.58 (1) and 2.25 (1) Å, respectively, as it is expected from their ionic radii values reported (1.16 vs 1.04 radii for both ion-species octahedral coordination). Finally, the Na-Y, Y-Y, and Na-Na next neighbor distances are close to 3.40 Å.
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All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.16-10/12/11,05:55:48) ... 344 Metastable, Mechanically... more
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.16-10/12/11,05:55:48) ... 344 Metastable, Mechanically Alloyed and ...
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All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.16-30/11/11,18:17:08) ... 212 Metastable, Mechanically... more
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.16-30/11/11,18:17:08) ... 212 Metastable, Mechanically Alloyed and ...
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... Page 6. 36 Nanophase Materials ACKNOWLEDGMENTS We thank Prof. G. Cocco for providing the facilities of the MA synthesis and for useful discussion. ... Sci. Forum 88-90,529 (1992) 4) E. Bonetti, G. Scipione, G. Valdré, G. Cocco, R.... more
... Page 6. 36 Nanophase Materials ACKNOWLEDGMENTS We thank Prof. G. Cocco for providing the facilities of the MA synthesis and for useful discussion. ... Sci. Forum 88-90,529 (1992) 4) E. Bonetti, G. Scipione, G. Valdré, G. Cocco, R. Frattini and PP Macrí, J. Appi. Phys. ...
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772 T7Z-Mechanical Alloying BM11 t¿¿M 11 ei ai. EXPERIMENTAL Ball milling was performed in a Spex Mill under either argon or hydrogen atmospheres. The details of the preparation procedure are given elsewhere [6]. The structure of the... more
772 T7Z-Mechanical Alloying BM11 t¿¿M 11 ei ai. EXPERIMENTAL Ball milling was performed in a Spex Mill under either argon or hydrogen atmospheres. The details of the preparation procedure are given elsewhere [6]. The structure of the powders was checked at various stages of ...
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All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.172-09/05/11,18:01:26) ... 380 Metastable, Mechanically... more
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.172-09/05/11,18:01:26) ... 380 Metastable, Mechanically Alloyed and ...
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—Annealing products of mechanically treated Al 75 Mo 25 powders have been studied by X-ray powder diffraction with the Rietveld method. The differential scanning calorimetry traces of as-milled powders showed transformation features whose... more
—Annealing products of mechanically treated Al 75 Mo 25 powders have been studied by X-ray powder diffraction with the Rietveld method. The differential scanning calorimetry traces of as-milled powders showed transformation features whose temperature decreased as a function of mechanical treatment time. Different phases were identified across the calorimetric events, which were also reported in the high-temperature phase diagram of the Al-Mo system, such as. Nevertheless, the solid state transformation processes activated in the calorimeter at ambient pressure are of different nature with respect to those observed by means of neutron diffraction during in situ annealing under vacuum. In the specimen mechanically alloyed for 32 hours the Al 12 Mo phase was observed after annealing with both processes. In the crystal geometry of Al 12 Mo, which is regarded as a first order approximation of the quasi-crystalline phase, the molybdenum atoms are arranged in a BCC fashion and are surrounded icosahedrally by twelve aluminum atoms.
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Hydrogen absorption and desorption properties in nanocrystalline LaMg 2 Ni are presented. Nanostructured phases have been obtained by milling grain coarse ingot and by mechanically alloying the parent elements. The structural and... more
Hydrogen absorption and desorption properties in nanocrystalline LaMg 2 Ni are presented. Nanostructured phases have been obtained by milling grain coarse ingot and by mechanically alloying the parent elements. The structural and hydriding properties were examined by X-ray diffraction, thermal analysis and thermal desorption measurements. Ball milling and mechanical alloying give a significant refinement of the microstructure. Reactive milling has been used for hydrogen absorption experiments. Hydrogenation by means of reactive milling at 300 K under a pressure of 0.4 MPa leads to the formation of a stable La-hydride phase together with an amorphous phase. Thermal desorption up to 983 K of hydrogenated samples leads again to parent LaMg 2 Ni phase.
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... The approximation of the profile by pseudo-Voigt functions (sum of Lorentz and Gauss terms ofequal width) has been explored in different cases which frequently occur in thecharacteriza-tion of materials by X-ray diffraction. ...
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Research Interests: Inorganic Chemistry, Raman Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, Nitrogen, and 8 morePhase Transformation, Surface Area, Thermal Stability, THEORETICAL AND COMPUTATIONAL CHEMISTRY, Structural Chemistry, Sol Gel Method, Rietveld method, and X ray powder diffraction
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Mg 60 Cu 30 Gd 10 and Mg 60 Cu 30 Gd 1.5 Nd 8.5 ribbons were obtained by melt spinning. For both compositions, a fully amorphous phase was found and a clear Tg was observed. In-situ XRD measurements were carried out during heating of... more
Mg 60 Cu 30 Gd 10 and Mg 60 Cu 30 Gd 1.5 Nd 8.5 ribbons were obtained by melt spinning. For both compositions, a fully amorphous phase was found and a clear Tg was observed. In-situ XRD measurements were carried out during heating of ribbons at the ID11 synchrotron beamline of ESRF, Grenoble (France). In order to identify the crystallisation products, an annealed Mg 60 Cu 30 Gd 10 master alloy was analysed by SEM/EDS and XRD. The existence of new ternary compounds (MgCu 4 Gd and Mg 2 CuGd) in the Mg-Cu-Gd system is suggested.
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... 1993)527-531 I,1,II North-Holland Structural and thermodynamic aspects of glass formation in Cu-Ti-H: role of hydrogen in mechanical alloying Marcello Baricco a, Livio Battezzati a, Giorgio Cocco b, Isabella Soletta b and Stefano Enzo... more
... 1993)527-531 I,1,II North-Holland Structural and thermodynamic aspects of glass formation in Cu-Ti-H: role of hydrogen in mechanical alloying Marcello Baricco a, Livio Battezzati a, Giorgio Cocco b, Isabella Soletta b and Stefano Enzo ca Dipartimento di Chimica Inorganica ...
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Nanopowders of Yttrium Aluminium Gar-net doped with neodymium ions were obtained by the co-precipitation method from the reaction of aluminium , yttrium and neodymium nitrate with ammonia.
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Structural properties of graded Si(1−x)Gex layers obtained on Si(100) by pulsed laser induced epitaxy were investigated by means of conventional powder x-ray diffraction and x-ray photoelectron spectroscopy. The Si(1−x)Gex epitaxial... more
Structural properties of graded Si(1−x)Gex layers obtained on Si(100) by pulsed laser induced epitaxy were investigated by means of conventional powder x-ray diffraction and x-ray photoelectron spectroscopy. The Si(1−x)Gex epitaxial layers were formed by pulsed KrF-laser driven rapid melting and crystallization of thin amorphous Ge layers deposited onto the Si(100). The experimental results showed that, by increasing the number of