Novel High-Temperature Antiferroelectric-Based Dielectric NaNbO3–NaTaO3 Solid Solutions Processed in Low Oxygen Partial Pressures
Novel High-Temperature Antiferroelectric-Based Dielectric NaNbO3–NaTaO3 Solid Solutions Processed in Low Oxygen Partial Pressures
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DOI：
10.1111/jace.12065
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发表时间：
2013-02
影响因子：
3.9
通讯作者：
Keisuke L. I. Kobayashi;M. Ryu;Y. Doshida;Y. Mizuno;C. Randall
中科院分区：
文献类型：
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作者：
Keisuke L. I. Kobayashi;M. Ryu;Y. Doshida;Y. Mizuno;C. Randall
研究了（1−x）NaNbO 3-（x）NaTaO 3固溶体（x ≤ 0.4）作为适用于贱金属内电极电容器应用的新型高温高介电常数介电体系。Ta的添加显著增强了电介质的电阻率，导致比主导多层陶瓷电容器电介质器件的电介质配制的BaTiO 3系统具有上级电阻率。的电容率的电压依赖性也是上级的钛酸钡基材料，在更高的温度下提供更高的电容。透射电子显微镜研究表明，晶粒具有所谓的核壳结构。根据电子衍射分析，核区具有反铁电相和铁电相之间的不均匀结构，壳区具有无公度的类铁电结构。核和壳区域分别具有富Nb和富Ta的组合物，并且它们的界面在组成上是尖锐的，这意味着壳区域在烧结过程中通过液相与不一致的Ta溶解再沉淀形成。我们预计，这些或基于碱金属钙钛矿的类似材料可以进一步增强，以提供150°C至250°C的电容器解决方案，这是许多新型AC-DC逆变器和发动机控制单元的重要范围。
The (1−x)NaNbO3–(x)NaTaO3 solid solution was investigated for x ≤ 0.4 in terms of new high-temperature and high-permittivity dielectric system that is suitable for base metal inner electrode capacitor applications. The addition of Ta significantly enhanced the resistivity of the dielectric, resulting in superior resistivity than the dielectrics-formulated BaTiO3 systems that dominate the multilayer ceramic capacitor dielectric devices. The voltage dependence of the permittivity was also superior to BaTiO3-based materials, providing higher capacitance at higher temperatures. A transmission electron microscopy study illustrated that the grains had so-called core-shell structure. According to the electron diffraction analysis, the core region had an inhomogeneous structure between antiferroelectric and ferroelectric phases, and shell region had an incommensurate ferroelectric-like structure. The core and shell region had Nb- and Ta-rich composition, respectively, and their interface was compositionally sharp, implying that shell region was formed via a liquid phase during the sintering process with an incongruent Ta dissolution reprecipitation. We anticipate that these or similar materials based on the alkali-niobate perovskites can be further enhanced to provide capacitor solutions from 150°C to 250°C, which is an important range for a number of new AC–DC invertor and engine control units.