[期刊论文]

出版年：2016

In this work, TiO₂-based varistor ceramics doped with Nb₂O₅, SiO₂ and Sm₂O₃ are prepared by using conventional solid state synthesis. X-ray diffractometry, scanning electron microscopy, energy dispersive spectrometer and direct current electrical measurement are used to study phase composition, microstructure and nonlinear properties. It is found that the second phase emerges at grain boundary, having a great influence on nonlinear electrical behaviors. Breakdown voltage E_1mA initially decreases and then increases with increasing of Sm₂O₃ content. The minimum of breakdown voltage E_1mA (9.3 V/mm) occurs at the composition of 99.0 %TiO₂–0.5 %Nb₂O₅–0.3 %SiO₂–0.2 %Sm₂O₃. Relative dielectric constant initially increases and then decreases. When the content of Sm₂O₃ increases to 0.3 %, the varistor has ultrahigh dielectric constant, which is consistent with its narrowest grain-boundary barriers. The nonlinear coefficient increases from 2.51 to 4.13 with increase of Sm₂O₃ from 0.0 to 0.4 %, and varistor of 98.8 %TiO₂–0.5 %Nb₂O₅–0.3 %SiO₂–0.4 %Sm₂O₃ owns the highest grain-boundary barriers.

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