Effect of Grain Size of BaTiO $$_{3}$$ 3 Ceramics on Thermal Expansion and Electrical Properties

Abstract

The thermal expansion behavior and electrical resistivity of BaTiO\(_{3}\) ceramics with different grain sizes were investigated. When they were heated and subsequently cooled in the range from 25 \(^{\circ }\)C to 200 \(^{\circ }\)C, the expansion and contraction curves of BaTiO\(_{3}\) ceramics with grain sizes of 600 nm and 1500 nm were not matched well to each other, and abnormal contraction and expansion behaviors were observed. For 30 nm and 150 nm BaTiO\(_{3}\) ceramics, the expansion and contraction curves basically are straight lines during heating. The linear thermal expansion coefficients (\(\alpha _\mathrm{L}\)) and the electrical resistivity of BaTiO\(_{3}\) ceramics were also measured. Experimental results showed that the value of \(\alpha _\mathrm{L}\) increases and the electrical resistivity decreases gradually with reducing grain size. This phenomenon can be attributed to the combination effect of the grain boundary and oxygen vacancies.