Abstract
β″-Al2O3 has been developed as a solid state electrolyte for the sodium-sulfur battery. Generally, raw material β″-Al2O3 was prepared by the wet-mixing process such as zeta-process. In this study, the dry-mixing process as a new safety procedure for the β″-Al2O3 raw material was investigated. Homogeneous mixtures were obtained by mixing 1-3mass% dispersing agent. However, anomalous grain growth was observed in this system during the sintering process. Seed crystal methods were also investigated for depression of anomalous grain growth during the sintering. Microstructure of sintered products was changed considerably by addition of more than 3mass% seed. The electrical resistivity of β″-Al2O3 thus obtained was significantly reduced by the addition less than 5mass% seed. It is considered that the electrical resistivity of β″-Al2O3 is governed by the number of grains and density of sintered products. The mechanical strength of seeded products was markedly higher than unseeded one's.
