Fedorchuk A. Intermetallides of gallium and rare-earth elements. Synthesis, structure, properties.

The dissertation is dedicated to the study of the interaction of gallium with rare-earth elements and metals or metalloids. Main peculiarities of the constitution of phase equilibria diagrams and crystal structures of the compounds are established. The peculiarities of the formation of the solid solutions based on binary phases are found. Electrical properties of a number of ternary gallides are studied. The ternary compounds in the Ln-M-Ga systems (Ln - rare-earth, M - metal or metalloid) form preferentially at a fixed content of rare-earth metals, such as 33, 25, or 20 at. %, and at simple ratios of the atoms with smaller atomic radii (M:Ga = 1:1, 1:2 and 2:1). The crystal structures of the compounds with more than 50 at. % Ga contain segments characteristic of the structure of elementary gallium. It was shown, that the structures of compounds containing the same amount of Ln atoms are related by structural deformations, whereas those of compounds with different Ln content are related by the insertion or subtraction of atoms, or by the multiple substitutions of atoms. A comparison of the investigated systems with related systems containing Al, In, Si or Ge is carried out. Keywords: crystallochemistry, gallides, phase equilibria, interrelations between the structures, interatomic distances, electrical resistivity.