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

The compounds ThCo5−5xFe5x and ThNi5−5xFe5x 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 Mossbauer 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 ThCo5−5xFe5x 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.