Crystal structure and magnetic properties of the DyMnxGa3 (x < 0.45) compounds with the AuCu3-type derivatives

Crystal structures of the ternary DyMnxGa3 alloys (x < 0.45) annealed stepwise at 873 and then at 773 K have been studied by the X-ray powder diffraction method. It was shown that four individual phases are formed in the vicinity of the specific stoichiometric compositions as a result of embedding of the manganese atoms into the octahedral holes of the high temperature DyGa3 compound. These phases are I-Dy5Mn1 Ga-y(15), II-Dy4Mn1 Ga-y(12), III-Dy3Mn1 Ga-y(9) and IV-Dy2Mn1 Ga-y(6). The crystal structures of these phases have been determined and considered as externally or/and internally distorted variants of the AuCu3-type structure. The temperature dependencies of magnetic susceptibility were determined by using the Faraday technique. All compounds studied are paramagnets in the temperature range of 300-650 K. The XPS analysis has confirmed that the crystal structure features of the DyMnxGa3 alloys and their magnetic properties are caused by the changing of an oxidation degree of the manganese atoms. (C) 2015 Elsevier B.V. All rights reserved.