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Crystallography, Cristallographie cristallogenèse, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Transport électronique, Electronic transport in condensed matter, Phénomènes de conductivité dans les semiconducteurs et les isolants, Conductivity phenomena in semiconductors and insulators, Transport en champ faible et mobilité; piézorésistance, Low-field transport and mobility; piezoresistance, Propriétés et matériaux magnétiques, Magnetic properties and materials, Diamagnétisme, paramagnétisme et superparamagnétisme, Diamagnetism, paramagnetism and superparamagnetism, Non métaux, Nonmetals, Etudes de matériaux magnétiques particuliers, Studies of specific magnetic materials, Semiconducteurs magnétiques, Magnetic semiconductors, Chrome Gallium Antimoniure Mixte, Chromium Gallium Antimonides Mixed, Mixto, Conductivité électrique, Electrical conductivity, Diffraction RX, XRD, Electronique spin, Spintronics, Electrónica de espin, Haute pression, High pressure, Matériau ferromagnétique, Ferromagnetic materials, Microscopie électronique balayage, Scanning electron microscopy, Moment magnétique, Magnetic moments, Paramagnétisme, Paramagnetism, Propriété magnétique, Magnetic properties, Réseau orthorhombique, Orthorhombic lattices, Réseau quadratique, Tetragonal lattices, Semiconducteur magnétique, Magnetic semiconductors, Traitement thermique, and Heat treatments

The electrotransport and magnetic properties of new phases in the Cr―GaSb system were studied. The samples were prepared by high-pressure (P = 6-8 GPa), high-temperature treatment and identified by x-ray diffraction and scanning electron microscopy. One of the CrGa2Sb2 phases with an orthorhombic structure Iba2 has a combination of ferromagnetic and semiconductor properties and is potentially promising for spintronic applications. Another high-temperature phase is paramagnetic and identified as tetragonal I4/mcm.

Crystallography, Cristallographie cristallogenèse, Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Structure des liquides et des solides; cristallographie, Structure of solids and liquids; crystallography, Etat cristallin (incluant les mouvements moléculaires dans les solides), Crystalline state (including molecular motions in solids), Aspects cristallographiques des transformations de phase; effets de la pression, Crystallographic aspects of phase transformations; pressure effects, Composé minéral, Inorganic compounds, Non métal, Nonmetals, Agrégat atomique, Atomic clusters, Amorphisation, Amorphization, Cinétique, Kinetics, Eau, Water, Effet pression, Pressure effects, Etude expérimentale, Experimental study, Fullerènes, Fullerenes, Germanium oxyde, Germanium oxides, Matériau semiconducteur, Semiconductor materials, Mode mou, Soft modes, Mode phonon, Phonon mode, Modo fonón, Relaxation réseau, Lattice relaxation, Silicium oxyde, Silicon oxides, Transformation phase, Phase transformations, Très haute pression, Very high pressure, C60, Ge O, GeO2, H O, H2O, O Si, SiO2, and c60

Copyright (c) 1997 Elsevier Science B.V. All rights reserved. A number of experimental methods have been applied to study the kinetics of high-pressure solid-state amorphization for some covalent crystals (Si, Ge and GaSb), molecular crystals, C60 and ionic oxides (stishovite and H2O), as well as the amorphous-to-amorphous transitions for H2O and GeO2. The low activation energy for the stishovite →a-SiO2 transition and appreciable variation of kinetic characteristics in the covalent compounds, depending on the number of components, were observed. Using high-pressure solid-state amorphization it is possible to obtain amorphous tetrahedral carbon by compression of C60-crystals. We have shown that the P-T kinetic lines for amorphization smoothly convert to the ordinary crystal-to-crystal hysteresis lines at high temperatures. For the first time experimental evidence for elastic softening in the vicinity of crystal-to-amorphous and amorphous-to-amorphous transitions is presented. The pressure and time dependence of the a-GeO2 volume changes were measured during the high-pressure transformation. The transition occurs in a wide pressure region and the volume has logarithmic time dependence at a fixed pressure. Comparison of the solid-state amorphization and amorphous-to-amorphous transition is made.

Chemical industry parachemical industry, Industrie chimique et parachimique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie minerale et origine de la vie, Inorganic chemistry and origins of life, Préparations et propriétés, Preparations and properties, Corps simples et composés non métalliques (oxydes, hydroxydes, hydrures, sulfures, carbures, ...), Elements and non-metal compounds (oxides, hydroxides, hydrides, sulfides, carbides, ...), Composé ternaire, Ternary compound, Compuesto ternario, Gallium Antimoniure, Gallium Antimonides, Galio Antimoniuro, Germanium Antimoniure, Germanium Antimonides, Germanio Antimoniuro, Semiconducteur, Semiconductor materials, Semiconductor(material), Solution solide, Solid solution, Solución sólida, Ga Ge Sb, and Ge1-x(GaSb)x

A new method of preparation of bulk amorphous solids is successfully applied to the semiconductor solid solutions Ge1-x(GaSb)x. The method consists in the solid-state disordering of a high-pressure phase on decompression. Large mutual solubility can be achieved for high-pressure phases of Ge and GaSb. Amorphization of metallic solid solutions occurs on decompression even at room temperature. Some data concerning the structure and stability of the amorphous semiconducting solid solutions a-Ge1-x(GaSb)x are presented.

Crystallography, Cristallographie cristallogenèse, Electronics, Electronique, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Equations d'état, équilibres de phases et transformations de phases, Equations of state, phase equilibria, and phase transitions, Transformations de phases particulières, Specific phase transitions, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Diagrammes de phases et microstructures développées par solidification et par transformations de phases solide-solide, Phase diagrams and microstructures developed by solidification and solid-solid phase transformations, Diagrammes de phases des métaux et alliages, Phase diagrams of metals and alloys, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Composé minéral, Inorganic compounds, Alliage binaire, Binary alloys, Aluminium alliage, Aluminium alloys, Calorimétrie, Calorimetry, Diagramme phase, Phase diagrams, Etude expérimentale, Experimental study, Silicium alliage, Silicon alloys, Solution solide sursaturée, Supersaturated solid solution, Solución sólida sobresaturada, Uebersaettigter Mischkristall, Système binaire, Binary systems, Al Si, and Système Al Si