Irina Anusca

Half antiperovskites: V. Systematics in ordering and group-subgroup relations for Pb2Pd3Se2, Bi2Pd3Se2, and Bi2Pd3S2

Abstract The crystal structures of Pb2Pd3Se2 and superconducting Bi2Pd3Se2 are investigated from single crystal X-ray diffraction. Thus, an enhanced view on structure trends can be given for the series Bi2M3Ch2 and Pb2M3Ch2 (M = Ni, Rh, Pd, Ch = S, Se) including structure-property relations to superconducting parkerite, Bi2Ni3S2, non superconducting Bi2Pd3S2, and trigonal shandite, Pb2Ni3S2. Systematics and deviations of the structure types are pointed out by group-subgroup relations from a common aristotype perovskite superstructure. Found structures and atomic site occupations are differenciated by means of Bärnighausen trees, M site ordering, coordination spheres, and polyhedra sharing [Ch2A4] as proposed by the scheme of ordered half antiperovskites A2M3Ch2 = AM3/2Ch (A = In, Sn, Tl, Pb, Bi; M = Co, Ni, Rh, Pd, and Ch = S, Se). Low dimensional partial structures with short M—M distances are analyzed with respect to the occurrence of superconductivity in parkerites.