Microstructure-Property Relationships in the BaTiO₃-SrTiO₃-CaTiO₃ System Ceramics

Abstract

Effect of process parameters as mixing and firing conditions on the varistor characteristics of BaTiO₃-SrTiO₃-CaTiO₃ system ceramics has been studied with special attention to the micro-and nano-structures. It is shown that well mix ing and control of Po₂ of ambient atmosphere during firing are most effective to attain high α (coefficient of V-I nonlinearity). In case of high Po₂, anomalous grain growth is predominant. On the other hand, in case of low Po₂, uniformly sized grain structure can be observed, but grain growth is insufficient. Adequate grain size and uniform microstructure are required for achieving high α. HRTEM observation showed grain boundary layer for high a ceramics, and facet grain boundary for low α ceramics.