CATION DISTRIBUTION IN GALLIUM-SUBSTITUTED YTTRIUM IRON GARNETS BY MOSSBAUER EFFECT SPECTROSCOPY

Recoil‐free nuclear‐resonance absorption was measured on Y3GatFe5‐tO12 powders with 1.75 ≦ t ≦ 4.0. A constant acceleration spectrometer was used, and the investigations were performed at room temperature, that is, above the Curie temperature of these compounds. For each material, we observed three resonant absorption maxima with different heights. The position of the maxima on the velocity scale is independent of composition. For each spectrum, two doublets which arise from the quadrupole splitting of the 57Fe nuclei are assigned; one doublet arises from the 57Fe nuclei in the tetrahedral(d) sites, whereas the other arises from the 57Fe nuclei in the octahedral (a). From the relative values for the intensities D and A for the d‐and a‐sites together with the known amount of t, the fraction x/t of the Ga3+ ions in the d‐sites was determined for each compound. The results were compared with work on cation distribution in substituted garnets obtained from 1. magnetization measurements, 2. X‐ray and neutron diffraction, and 3. thermodynamics of solid solutions. At Ga concentrations t ⪆ 2.0, our results deviate from the ones obtained from magnetization data. The distribution function proposed under 3. from the equilibrium conditions for ions in multisublattice structures is consistent with the experimental data presented in this paper. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim