Structure and physical properties of rare-earth zinc antimonides REZn1–xSb2 (RE=La, Ce, Pr, Nd, Sm, Gd, Tb)

The ternary rare-earth zinc antimonides REZn1–xSb2 (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 REZn0.6Sb2, with no appreciable homogeneity range. These compounds adopt the HfCuSi2-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 (Tc=2.5 K) and antiferromagnetic Tb (TN=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).