Sintering of SrSiO₃ Ceramics and Its Dielectric Property

Abstract

Powders of SrSiO₃ have been prepared by the sol-gel method using tetraethoxysilane and strontium hydroxide. Sinterability of the powder and microstructure and dielectric property of the sintered bodies have been examined. The powders densified without additives as sintering aid, however, sinterability and microstructure changed largely depending on the SrO/SiO₂ ratio and impurities. A small amount of ZrO₂ as impurity caused remarkable abnormal grain growth, and the formation of SrO-ZrO₂-SiO₂ glass was recognized at tripple point of grain boundaries. When the SrO/SiO₂ ratio exceeded unity, prismatic particles grew and impeded the densification. The starting batch composition containing 5mol% excess SrO gave the highest relative density of 98.2% throughout this study. On the other hand, liquid phase sintering by addition of BaO-Al₂O₃ components lowered the densification temperature. However, large closed pores remained in the microstructure and the range of sintering temperature became narrow. The dielectric constant of all the specimens was about 6.5 and dielectric loss was 1×10^-4-3×10^-4. The dielectric loss decreased with decreasing amount of grain boundary phase in the specimens.