Synthesis and analysis of the magnetic properties of YIG by means of sol–gel and spark plasma sintering

Abstract

We presented a study on the structure and magnetic properties of yttrium iron garnet (YIG), Y3Fe5O12, which was synthesized by means of sol–gel method and spark plasma sintering (SPS). The YIG nanoparticles were prepared by sol–gel method followed by 800 °C annealing for 3 h. SPS procedures with different temperatures (700 °C∼900 °C) and holding times (30 min ∼ 90 min) were performed to study the influence of SPS conditions on the structure and magnetic properties of YIG. The X-ray diffraction pattern and Raman spectrum confirmed the presence of YIG at all studied conditions. All samples were pure garnet phase except for the samples with too high temperatures (900 °C) and too long holding time (90 min). The impurities were inferred to be due to the hypoxic environment caused by the vacuum sintering condition of SPS. The magnetic properties of YIG samples were significantly affected by SPS conditions. The YIG sample became multi-domain at the temperature as low as 750 °C and grew to 89.1 nm at 850 °C for 30 min holding time benefiting from to the special sintering effect of SPS. Large particles with loose texture were formed by the formation of sintering neck between the adjacent particles when the SPS temperature was higher than 800 °C. It are confirmed that the sample with extended holding time at a moderate temperature (800℃/60 min) show the best soft-magnetic properties, whose Ms, Mr and Hc are 27.5 emu/g, 2.4 emu/g and 19.2 Oe respectively. The results show that this method has good potential in preparing YIG with good magnetic properties.