Crystal structure and magnetic properties of the DyMn_xGa₃ (x < 0.45) compounds with the AuCu₃-type derivatives

Highlights: • We study the crystal structure of DyMn_xGa₃ alloys (x < 0.45). • Alloys studied are interstitial solid solutions with Mn in DyGa₃. • Crystal structures differ both by external and internal distortion. • The effective magnetic moments have been calculated. • Magnetic moments' changes correlate with features of crystal structure. - Abstract: Crystal structures of the ternary DyMn_xGa₃ 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-Dy₅Mn_1−yGa₁₅, II-Dy₄Mn_1−yGa₁₂, III-Dy₃Mn_1−yGa₉ and IV-Dy₂Mn_1−yGa₆. 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 DyMn_xGa₃ alloys and their magnetic properties are caused by the changing of an oxidation degree of the manganese atoms