Alloy Systems and Compounds Containing Rare Earth Metals and Carbon

Abstract

Data on binary, ternary, and multicomponent systems and compounds containing rare earth and carbon known through the beginning of 2017 and methods of their synthesis are critically reviewed. Selected superconducting and magnetic systems are discussed to highlight some more specific and characteristic physical properties of binary and ternary rare earth (transition metal) carbides. Thereby, general trends observed in 16 binary R–C and more than 70 ternary R–T–C (T = d -element) phase diagrams and in the crystal chemistry of more than 400 binary and ternary carbides belonging to more than 60 structure types have been evaluated. Crystal structures of known carbides are briefly analyzed. Three species of carbon occur in these structures: isolated carbon atoms, C 2 units, and C 3 units. Relationships between structure types of binary rare earth carbides as derived from the cubic NaCl type have been evaluated. All 50 known structure types of the R–T–C ternary compounds are classified into two groups: metal-rich carbides (intermetallics) and carbometalates depending on carbon content and M/C ratio (M = metal atoms). Complex anions [T y C z ] n – of different dimensionalities could be identified in the crystal structures of carbometalates. These data can be used for the prediction and synthesis of new rare earth carbides for basic research as well as for technical applications.