Influence of Ge and GeO₂ on the microstructure and varistor properties of TiO₂-Ta₂O₅-CaCO₃ ceramics

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• 作者：Kunyong Kang^a ; Zhifeng Zheng^a ; Sida Xie^a ; Jun Zhang^a ; Kaimeng Xu^a ; Lei Tao^a ; Xuequan Rong^b ; Zhefeng Xu^c ; Jikang Yan^c ; ^d ; ^e ; ^{scyjk@163.com} ; Guoyou Gan^c ; ^d ; ^e ; ^{ganguoyou@sina.com}
• 关键词：TiO2 varistor ; Microstructure ; Varistor property ; Co-doping ; Ge ; GeO2
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：43
• 期：4
• 页码：3465-3474
• 全文大小：2036 K
• 卷排序：43

文摘

This study investigated the effect of elemental crystal Ge or/and GeO2 doping on the microstructure and varistor properties of TiO2–Ta2O5–CaCO3 varistor ceramics, which were prepared via the traditional ball milling–molding–sintering process. X-ray diffraction, scanning electron microscopy, scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy demonstrated that co-doping with Ge and GeO2 changed the microstructure of TiO2–Ta2O5–CaCO3 ceramics, thereby increasing the nonlinear coefficient and decreasing the breakdown voltage. The optimum doping concentrations of Ta2O5, CaCO3, Ge, and GeO2 exhibited the highest nonlinear coefficient (α=14.6), a lower breakdown voltage (EB=18.7 V mm−1), the least leakage current (JL=10.5 μA cm−2), and the highest grain boundary barrier (ΦB=1.05 eV). In addition, Ge and GeO2 function as sintering aids, which reduce the sintering temperature because of their low melting points.