Ge-added TiO2–Ta2O5–CaCO3 varistor ceramics. Issue 4 (March 2016)

• Record Type: Journal Article
• Authors: Kang, Kunyong; Yan, Jikang; Gan, Guoyou; Du, Jinghong; Zhang, Jiamin; Liu, Yichun
• Is Part Of: Ceramics international. Volume 42:Issue 4(2016)
• Page Start: 4739
• Page End: 4747
• Publication Date: 2016-03
• Subjects: TiO2 varistor -- Liquid-phase sintering -- Nonlinear coefficient -- Breakdown voltage -- Ge; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2015.11.151
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: The influence of doping with Ge on the nonlinear coefficient α and the breakdown electric field E B of TiO2 –Ta2 O5 –CaCO3 varistor ceramics was investigated. In this study, TiO2 –Ta2 O5 –CaCO3 varistor ceramics added with Ge was successfully prepared using the traditional method of ball milling–molding–sintering. The electrical performance, including the nonlinear coefficient α, the breakdown electric field E B, and the leakage current J L, are tested using a varistor direct current parameter instrument. The average barrier height Φ B of each sample is calculated using the relevant formula. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and scanning transmission electronic microscopy analyses demonstrated that Ge doping notably changed the microstructure of TiO2 –Ta2 O5 –CaCO3 ceramics, thereby increasing α and decreasing E B . When the doping contents of Ta2 O5 and CaCO3 were 0.2 and 0.4 mol%, respectively, the optimum doping content of 0.9 mol% Ge exhibited high α (10.2), low E B (14.1 V mm −1 ), and high Φ B (0.95 eV). These results are superior to previous findings. In addition, Ge as sintering aid reduced the sintering temperature caused by the low melting point. The optimal sintering temperature was 1300 °C for the TiO2 –Ta2 O5 –CaCO3 ceramics doped with Ge.