Synthesis of Dense, Fine-Grained YIG Ceramics by Two-Step Sintering

A two-step sintering (TSS) process has been used to fabricate yttrium iron garnet (YIG) ceramics with high density and fine grain size. The densification, microstructure, and magnetic properties were investigated. The sample prepared by the TSS process with first-step sintering temperature (T1) of 1350°C, second-step sintering temperature (T2) of 1300°C, and holding time of 18 h had density above 99% of theoretical and exhibited uniform microstructure with small average grain size (2.4 μm). The saturation magnetization (MS) of this sample reached 27.4 emu/g. These results indicate that the TSS process can effectively suppress grain-boundary migration while maintaining active grain-boundary diffusion to obtain dense, fine-grained YIG ceramics with appropriate magnetic properties.