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Synthesis, Microstructure, Dielectric Properties, and Insulation Resistance of SrTiO₃ Grain Boundary Layer Ceramic Capacitors

W. Bai, Y. Zhou, M. Xiao, X. Zhao, L. Xu, H. Xiao, Y. Tong, C. He, J. Pan, Q. Xie, C. Yang, C. Yang

Journal of Ceramic Science and Technology, Vol. 14, No. 2 (2023), pp. 99-106

DOI: 10.4416/JCST2023-00010

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Abstract

SrTiO3 grain boundary layer capacitors were prepared by means of a two-step sintering method. The effects of sintering conditions and CuO content in a CuO-PbO-Bi2O3-B2O3 oxidant on the microstructure, dielectric properties, and insulation resistance of the SrTiO3 capacitors were investigated. The results showed that during semi-conducting sintering, the SrTiO3 grain size increased with increasing sintering temperature, while the porosity decreased and the ceramic became denser. The SrTiO3 capacitor produced at a sintering temperature of 1 420 °C for 2 hours exhibited a maximum dielectric constant of 24 491, a minimum dielectric loss of 0.02 (1 MHz), and a resistance below 0.2 Ω. Furthermore, CuO was used as a partial replacement for PbO during insulating sintering. And the SrTiO3 capacitor achieved optimal performance with a CuO content of 20 wt%, exhibiting a maximum dielectric constant of 26 094, a capacitance temperature coefficient ΔC/C (- 55 °C – 125 °C) ≤ ± 20 %, a dielectric loss below 0.01 (1 MHz), and an average insulation resistance of 90 GΩ (50 V). This research provides a feasible approach to systematically explore the semi-conducting and insulating processes for SrTiO3 grain boundary ceramic capacitors, as well as to develop a low-lead oxidant coating.

Keywords

SrTiO3 ceramics, two-step sintering, dielectric properties, oxidant, insulation resistance value

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