Microstructure and Grain Boundary Structure of Na+-Diffused (Sr,Ca)TiO3 Capacitor-Varistor Ceramics |
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Authors: | Qing Zou Zhongyan Meng |
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Affiliation: | Department of Electronic Engineering, Xi'an Jiaotong University, Xi'an, 710049, China |
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Abstract: | The microstructure of (Sr,Ca)TiO3 capacitor-varistor materials has been investigated by employing electron microscopy techniques (TEM, STEM, HREM, EDX, and EPA). The material is found to contain (Sr,Ca)TiO3 grains (∼30 μm) having perovskite crystal structure with domains, a Na+-diffused layer at the grain boundaries which is dependent on thermal diffusion conditions, and multiple-grain junctions in which the Ti n O2n–1 Magneli phase coexists with an amorphous intergranular phase. In addition, wider grain boundaries (10–30 nm), thin grain boundaries (∼1 nm), and clean grain boundaries which are free from intergranular phase were observed, and the effects of different grain boundaries on the diffusion of Na+are discussed. |
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