Structural and magnetic properties in the polymorphs of CeRh0.5Ge1.5

Abstract

We investigate the structural and magnetic properties in the polymorphs of a new compound CeRh0.5Ge1.5. Depending upon the starting materials, and the slightly different synthesis method, we find that CeRh0.5Ge1.5 compound exists in two different space groups. The first compound, alpha-CeRh0.5Ge1.5 crystallizes in tetragonal alpha-ThSi2 structure type in space group I4(1)/amd with lattice parameters, a=4.2034(6) angstrom and c=14.770(3) angstrom. In this structure, the cerium atoms occupy the position between the Rh/Ge tetrahedral layers. On the other hand, the second compound, namely beta-CeRh0.5Ge1.5 crystallizes in the AlB2 type hexagonal structure in space group P6/mmm, with lattice parameters, a=4.2615(7) A and c=4.1813(9) angstrom. The crystal structure of beta-CeRh0.5Ge1.5 consists of two dimensional Rh/Ge hexagonal units and the cerium atoms are sandwiched between them. Magnetization studies exhibit magnetic ordering, as evident from a sharp peak in the plot of magnetic susceptibility measured as a function of temperature in a fixed magnetic field, in alpha-CeRh0.5Ge1.5 and beta-CeRh0.5Ge1.5 at 3.6 K and 12 K, respectively. Structural and magnetic properties of both compounds are presented and discussed here. (C) 2014 Elsevier Inc. All rights reserved.