Ternary Aluminides of a New Homologous Series—CePt2Al2 and CePt3Al3: Crystal Structures and Thermal Properties

In the process of studying the Ce–Pt–Al system, we identified CePt2Al2 and CePt3Al3, two new ternary intermetallic compounds. CePt2Al2 aluminide undergoes a structural phase transition from a low-temperature orthorhombic modification (of its own structure type, Cmme, a = 5.84138(2) A, b = 6.39099(3) A, c = 10.11611(5) A) to a high-temperature tetragonal modification (CaBe2Ge2 type, P4/nmm, a = 4.3637(9) A, c = 10.0925(14) A) at 280(1)°C. CePt3Al3 crystallizes with a new type of structure (Cmme, a = 6.36548(6) A, b = 5.78301(6) A, c = 13.36245(19) A) built of structural units of low-temperature orthorhombic CePt2Al2-type and CsCl-type.