Sintering and grain growth control of high dense YIG

The densification and grain growth of yttrium iron garnet (YIG) were systematically studied to produce highly densified YIG via conventional solid-state route (CSSR). The percentage of purity and structure of YIG was confirmed by XRD characterization. SEM micrographs revealed that with increasing sintering temperature and time, the grain size and the average pores radius (Rp) increased, while the number of pores per volumes (Nv) decreased. The maximum material density obtained using Archimedes principle was 97.9% of that of theoretical density (ρtheory). It required approximately 132.55 kJ/mol of energy to produce dense YIG sintered for 6 h at 1420 °C. However, beyond this temperature, a new phase that confirmed the presence of YFe2O4-δ phase was found through EDX analysis along the grain boundaries. This occurrence lowered the grain boundary mobility thereby resulting in slight change in density. Therefore, the results suggested that a highly densified YIG (ρtheory of ≈98%) could be successfully obtained when YIG is sintered at 1420 °C for 6 h.