Structural, Mössbauer spectroscopy and magnetic investigations of Gd3Fe5O12 garnets obtained by spark plasma sintering

This work presents a detailed analysis of the structural and magnetic configuration of bulk Gd₃Fe₅O₁₂ obtained by spark plasma sintering (SPS) at 1100 °C for a dwell time of 1 min. While X-ray diffraction analysis proves formation of the single phase with the gadolinium iron garnet structure, temperature dependent Mössbauer spectroscopy provides more insight on the atomic scale occupancy and local magnetic configurations. It is shown that SPS processing does not alter significantly nor the compound stoichiometry or the compensation temperature, as compared to a reference sample obtained by conventional solid-state reaction and previously reported by our group. In both samples, a limited cationic inversion of about 10% between Fe and Gd ions in the octahedral sites is observed. Despite this, compensation temperature, when compared with data from the literature available only for thin films, reaches an unprecedented value of 317 K. The saturation magnetization of 121.4 emu/g (at 5 K) represents the highest value reported so far on Gd₃Fe₅O₁₂ bulks. Our results indicate that SPS processing increases the material’s potential for practical applications, including the possibility to obtain high quality targets for thin films deposition.