Structural and magnetic properties of Er3Fe5−xGaxO12 garnets

Abstract

Gallium substituted erbium iron garnets (ErFe5−xGaxO12) prepared by solid state reaction method using ball milling and sintering at 1300 °C were all single-phase compounds with Ia3d symmetry. The lattice parameter and cell volume decreased slightly, whereas the x-ray density increased linearly with the increase of Ga concentration. XRD analysis, Mössbauer spectroscopy, and the magnetic data, all provided evidence of Ga3+ substitution for Fe3+ at tetrahedral sites in the composition range up to x = 0.6, and a small partial substitution at octahedral sites in the sample with x = 0.8. The saturation magnetization decreased almost linearly in accordance with a simple magnetic dilution model in the concentration range up to 0.6, and deviated slightly from this behavior at x = 0.8 due to partial substitution at octahedral sites. The low temperature thermomagnetic measurements on the unsubstituted sample revealed a compensation temperature at −186 °C, whereas the sample with x = 0.8 exhibited a minimum at a significantly higher temperature of −51 °C, with significant broadening.