Structures and physical properties of R₂TX₃ compounds

Rare-earth compounds have been a subject of intensive research based on the unique electronic structures of the rare-earth elements. Novel ternary intermetallic compounds R₂TX₃ (R=rare-earth element or U, T=transition-metal element, X=Si, Ge, Ga, In) is a significant branch of this research field due to their complex and intriguing physical properties, such as magnetic order at low temperature, spin-glass behavior, Kondo effect, heavy fermion behavior, and so on. The unique physical properties of R₂TX₃ compounds are related to distinctive electronic structures, crystal structures, micro-interaction, and external environment. Most R₂TX₃ compounds crystallize in AlB₂-type or derived AlB₂-type structure and exhibit many similar properties. This paper gives a concise review of the structures and physical properties of these compounds. Spin glass, magnetic susceptibility, resistivity, and specific heat of R₂TX₃ compounds are discussed.