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The Mossbauer effect has been used to study the magnetic properties of pseudobinary (Er,Gd)Fe3 compounds. The spectra show that the spin-reorientation temperature, Tr, decreases with increasing Gd concentration. This decrease is explained by the concentration dependence of the average crystal field anisotropy at the (Er, Gd) sites. A simple single-ion model for the free energy was used to describe the magnetocrystalline anisotropy. The model adequately describes the concentration dependence of the reorientation temperature.

Results of magnetisation and 57Fe Mossbauer measurements show that the strong ferromagnetic coupling in Pd3Fe is markedly altered in the hydride Pd3FeH0.7. The magnetic moment of (4.59+or-0.03) mu B is reduced by the presence of hydrogen to (0.83+or-0.03) mu B. This reduction is accompanied by a decrease of approximately 46% in the magnetic transition temperature of the hydride compared with that of Pd3Fe (499K). In addition Mossbauer spectra at 4.2K in external magnetic fields indicate that anisotropic antiferromagnetic coupling dominates in the hydride. Results are compared with those for Pd2AuFe where similar effects are observed.