Crystal Structure and Point Defects of the Ternary Phase Gd1+nFe12xyMox□y (□ = Vacancy)

Abstract

X-ray powder diffraction and Rietveld refinement were used to investigate the structural details of the ThMn12-type compounds in the Fe–Gd–Mo ternary system. It has been shown that 8(f)- and 8(j)-crystallographic sites are partially filled with only Fe atoms. The 2(a)-site filled exclusively by Gd and the 8(i)-site that allows mixing of Fe and Mo was found to be completely occupied. It has been established that ThMn12-type structure allows a small part of Gd atoms to be located on the 8(i)-positions (antistructural defects). The experimentally measured mass density of the compact samples was compared with the theoretical densities calculated on the base of different possible defect structures. The best agreement was achieved under the assumption that two types of defects are present simultaneously: vacancies on Fe sites and Gd atoms substituting for Fe atoms.