Synthesis and crystal structures of RE7Zn21+xSi2–x [RE = Ce, Pr, and Nd; 0.09?(1) < x < 0.95?(1)]

摘要

The focus of this paper is on the synthesis and crystal structures of three Zn-rich compounds with the general formula RE7Zn21+xSi2?x, where RE = Ce [x = 0.95?(1); heptacerium docosazinc silicon], Pr [x = 0.09?(1); heptapraseodymium henicosazinc disilicon], and Nd [x = 0.53?(1); heptaneodymium docosazinc silicon]. The compounds were obtained by high-temperature reactions, using the respective elements as starting materials. The structures were determined by single-crystal X-ray diffraction. The title compounds crystalize in the orthorhombic space group Pbam (No. 55, Pearson symbol oP60) and are isostructural with about a dozen RE7Zn21+xTt2?x (RE = La–Nd; Tt = Ge, Sn, and Pb) compounds previously reported by our group. The results from the present refinements confirm the previously published data on RE7Zn21+xSi2?x (RE = La and Ce; x? 1.45) [Malik et al. (2013). Intermetallics, 36, 118–126]. Additionally, magnetic susceptibility measurements on the corresponding bulk samples show Curie–Weiss paramagnetic behavior from 5 to 300?K, consistent with RE3+ ground states and local-moment magnetism due to the core 4f electrons.