Microstructure and dielectric characteristics of Nb₂O₅ doped BaTiO₃-Bi(Zn_l/2Ti_l/2)O₃ ceramics for capacitor applications

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• 作者：Yangyang Lu^a ; Hua Hao^a ; ^{haohua@whut.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Shujun Zhang^a ; ^b ; Hanxing Liu^a ; Cong Su^a ; Zhonghua Yao^a ; Minghe Cao^a
• 关键词：X9R ; MLCC ; Dielectric properties ; Microstructure
• 刊名：Journal of the European Ceramic Society
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：37
• 期：1
• 页码：123-128
• 全文大小：1892 K

文摘

The effects of Nb₂O₅ addition on the dielectric properties and phase formation of 0.8BaTiO₃-0.2Bi(Zn_l/2Ti_l/2)O₃ (0.8BT-0.2BZT) ceramics were investigated. The desired perovskite phase was achieved with Nb₂O₅ doping levels being in the range of 0.5 wt.%–3.0 wt.%. The 0.8BT-0.2BZT ceramics doped with 1.5 wt.% Nb₂O₅ was found to possess a moderate dielectric constant (ε = 1170) and low dielectric loss (tanδ = 1%) at room temperature and 1 kHz frequency, showing a flat dielectric behavior over the temperature range of −55 °C–200 °C. Based on this composition, the X9R-MLCC (multilayer ceramic capacitor) with Ag0.7-Pd0.3 electrode was sintered at 1060 °C. The optimized capacitance of the MLCC is 26.5 nF, with dielectric loss tanδ of 0.9% and electrical resistance of 4.50 × 10¹¹ Ω at room temperature, leading to a high time constant of 11,900 s, decreasing to 175 s at 200 °C, being one order higher than those of commercial X7R MLCC. In addition, the equivalent series resistance (ESR) was found to be on the order of 0.2 mΩ at 2 MHz, much lower than that of the DC Bus Capacitor Bank for the automotive inverters (where the desired characteristic is <3 mΩ). All these characteristics of the newly developed MLCC will benefit the high temperature and high power capacitor applications.