Structure and physical properties of rare-earth zinc antimonides REZn 1–xSb 2 ( RE=La, Ce, Pr, Nd, Sm, Gd, Tb)

Abstract

The ternary rare-earth zinc antimonides REZn 1– x Sb 2 ( RE=La, Ce, Pr, Nd, Sm, Gd, Tb) were prepared by heating at 1050 °C followed by annealing at 600 °C. For all members, single-crystal X-ray diffraction studies indicated that the Zn deficiency is essentially fixed, corresponding to the formula REZn 0.6Sb 2, with no appreciable homogeneity range. These compounds adopt the HfCuSi 2-type structure (Pearson symbol tP8, space group P4/ nmm, Z=2). Single-crystal electrical resistivity measurements confirmed the occurrence of an abrupt resistivity decrease near 4 K for RE=Ce, and a less pronounced one for RE=La, Pr, and Gd. Except for the ferromagnetic Ce ( T c=2.5 K) and antiferromagnetic Tb ( T N=10 K) members, all remaining compounds exhibit no long-range magnetic ordering down to 2 K, instead showing temperature-independent ( RE=La), van Vleck ( RE=Sm), or Curie–Weiss paramagnetism ( RE=Pr, Nd, Gd).