Structure and electrical resistivity of rare-earth zinc bismuthides REZn1−xBi2 (RE=La, Ce, Pr)

Abstract The ternary rare-earth zinc bismuthides REZn 1− x Bi 2 (RE = La, Ce, Pr) were synthesized by reaction of pure metals. Single-crystal X-ray diffraction studies showed that these compounds adopt a defect HfCuSi 2 -type structure (Pearson symbol tP 8, space group P 4/ nmm , Z = 2). The structure refinement led to the final compositions LaZn 0.52(1) Bi 2 ( a = 4.599(1) A, c = 9.987(2) A), CeZn 0.47(1) Bi 2 ( a = 4.572(1) A, c = 9.830(2) A), and PrZn 0.49(1) Bi 2 ( a = 4.554(1) A, c = 9.745(1) A). Severe strain in the Zn-centred tetrahedra as the structure is contracted leads to the development of split Bi1 sites in PrZn 0.5 Bi 2 . Resistivity measurements indicate metallic behaviour, with the occurrence of an abrupt decrease below 5 K for CeZn 0.5 Bi 2 .