Study of the Mössbauer Effect, Magnetization, and Crystal Structures of the Pseudobinary Compounds ThCo5−5xFe5x and ThNi5−5xFe5x

Abstract

The compounds ThCo_5−5xFe_5x and ThNi_5−5xFe_5x form two series of complete solid solutions. All compounds investigated show the hexagonal CaCu₅ structure. The lattice constants, the Curie temperatures, and the saturation moments at 4.2 K have been determined as a function of x. The ThM₅ compounds possess two nonequivalent crystallographic sites for the M atoms (M = Fe, Co, Ni). By means of the Mössbauer effect it is shown that the physical nature of atoms occupying these sites differs appreciably. It is also shown that replacement of Co or Ni by Fe in ThCo₅ or ThNi₅ proceeds with a strong preference for one of these two sites. The crystalline anisotropy of the compounds ThCo_5−5xFe_5x was studied as a function of x. It could be shown that the anisotropy in ThCo₅ is not particularly due to one of the two Co sites. With decreasing values for x, starting from ThFe₅, the Fe moment increases down to x = 0.6. This is explained in terms of a rigid‐band model.