Synthesis and crystal structures of RE7Zn(21+x)Si(2-x) [RE = Ce, Pr, and Nd; 0.09 (1) < x < 0.95 (1)

Abstract

The focus of this paper is on the synthesis and crystal structures of three Zn-rich compounds with the general formula RE7Zn(21+x)Si(2-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 RE7Zn(21+x)Tt(2-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 RE7Zn(21+x)Si(2-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 RE(3+) ground states and local-moment magnetism due to the core 4f electrons.