Abstract
Microstructure properties of barium-titanate based materials, expressed in grain boundary contacts, are of basic importance for electric properties of this material. In this study, the model of intergranular impedance applied on a two-grain contact is considered. Globally, a BaTiO3-ceramics sample consists of a large number of mutually contacted grains, which form clusters. Such clusters can be presented as specific fractal formations. For each of them, it is possible to establish the equivalent electrical model and, for a defined set of input parameters, using symbolic analysis, obtain the frequency diagram. The influence of fractal structure is especially stressed. Realizing the totality of relations between cluster grain groups, their microelectrical schemes and corresponding frequency characteristics, on one hand, and the global equivalent electrical scheme and corresponding acquired frequency characteristics of BaTiO3-ceramics samples, on the other hand, we set a goal of correlating experimental results with the summing effect of microelectric equivalent schemes. The model is successfully tested on doped barium-titanate ceramics.
Highlights
Doped barium-titanate ceramic is attracting much interest for its application as resistors with a positive temperature coefficient of resistivity (PTCR), multilayer ceramic capacitors (MLCC), thermal sensors etc [1, 2]
In order to establish the model of intergranular impedance for doped barium titanate, it is important to notice that microstructure properties of BaTiO3 based materials, expressed in their grain boundary contacts, are of basic importance for electric properties of these materials
The model of intergranular impedance is established using the equivalent electrical scheme characterized by a corresponding frequency characteristic
Summary
Doped barium-titanate ceramic is attracting much interest for its application as resistors with a positive temperature coefficient of resistivity (PTCR), multilayer ceramic capacitors (MLCC), thermal sensors etc [1, 2]. In the process of BaTiO3-ceramics consolidation, technological parameters like pressing pressure, initial sample's density, sintering temperature and time, as well as different dopants, essentially determine the final electrical properties of the ceramics. A slight change of a particular consolidation parameter, or the change of the dopant concentration can significantly change the microstructure, influencing electrical properties of the specimens. Since grain size and distribution considerably affect electrical properties of barium-titanate based materials, correlation of their microstructure and electrical properties has been investigated most extensively by numerous authors [3,4,5]. Mitic et al /Science of Sintering, 41 (2009) 247-256
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