CaAl2Si2-type Arsenides RE2/3Zn2As2 (RE = La, Ce, Pr, Nd, Sm)

André T. Nientiedt, Hannes Lincke, Ute Ch. Rodewald, Rainer Pöttgen, Wolfgang Jeitschko
2011 Zeitschrift für Naturforschung. B, A journal of chemical sciences  
The ternary arsenides RE2/3Zn2As2 (RE = La, Ce, Pr, Nd, Sm) were synthesized from the elements in NaCl/KCl salt fluxes and were characterized by powder X-ray diffraction. The Ce2/3Zn2As2 structure was refined on the basis of single-crystal X-ray diffractometer data: CaAl2Si2 type, P¯3m1, Z = 1, a = 417.17(6), c = 703.7(1) pm, wR2 = 0.0353, 211 F2 values, 11 variables, SOF(Ce) = 62.9(5) %. The zinc and arsenic atoms form a two-dimensional network of edge-sharing ZnAs4/4 tetrahedra with Zn-As
more » ... edra with Zn-As distances of 253 pm. These covalently bonded [Zn2As2]2− layers are separated and charge-balanced by the cerium atoms. Each cerium atom has a slightly distorted octahedral arsenic coordination (Ce-As 302 pm). The defect type of the RE2/3Zn2As2 arsenides is discussed with respect to isotypic sulfides RE2/3Cu2S2.
doi:10.1515/znb-2011-0302 fatcat:rclk2j2aszbrvbr6lp3xuxczl4