Structures and physical properties of R sub(2)TX sub(3) compounds

Rare-earth compounds have been an attractive subject based on the unique electronic structures of the rare-earth elements. Novel ternary intermetallic compounds R sub(2)TX sub(3) (R = rare-earth element or U, T = transition-metal element, X = Si, Ge, Ga, In) are 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 R sub(2)TX sub(3) compounds are related to distinctive electronic structures, crystal structures, microinteraction, and external environment. Most R sub(2)TX sub(3) compounds crystallize in AlB sub(2)-type or derived AlB sub(2)-type structures 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 R sub(2)TX sub(3) compounds are discussed.