Chen Hetuo, Fu Xuewen, An Qi, Tang Bin, Zhang Shuren, Yang Hao, Long Yin, Harfouche Mark, Wang Huolei, Li Yingxiang
State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.
Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California, USA.
Sci Rep. 2017 Oct 26;7(1):14120. doi: 10.1038/s41598-017-14333-9.
Microwave dielectric ceramic materials are extensively utilized in microwave applications because of their high dielectric constants and quality factors. These applications also require ceramics of zero temperature coefficients at the resonant frequency (τ ), which can be realized through mixing a ceramic that one is interested in with another ceramic with -τ , or by performing the ionic substitution. With the mixing/ionic substitution, it is indispensable to compute the quality factors precisely. Previous study indicates that the quality factor depends on the grain size, porosity, internal strain, structure, phase evolution, and conductivity etc. Here we derive a quality factor formula based on the definition, which works very well for multiphase composites, single phase solid solutions, and equivalent ionic substituted single phase materials. Our formula calculation and fits to the previous experimental results demonstrate that the quality factor of the ceramic mixtures strongly depend on the dielectric constants and the dielectric constant variation index. Our results suggest that the impacts from grain size, porosity, and internal strain etc. can be summarized to the dielectric constant or dielectric constant variation index, which is of great importance for future design of high performance microwave dielectric ceramics.
微波介电陶瓷材料因其高介电常数和品质因数而被广泛应用于微波领域。这些应用还要求陶瓷在谐振频率下具有零温度系数（τ ），这可以通过将感兴趣的一种陶瓷与另一种具有 -τ 的陶瓷混合，或通过进行离子取代来实现。通过混合/离子取代，精确计算品质因数是必不可少的。先前的研究表明，品质因数取决于晶粒尺寸、孔隙率、内部应变、结构、相演变和电导率等。在此，我们基于定义推导了一个品质因数公式，该公式对多相复合材料、单相固溶体和等效离子取代单相材料都非常适用。我们的公式计算以及与先前实验结果的拟合表明，陶瓷混合物的品质因数强烈依赖于介电常数和介电常数变化指数。我们的结果表明，晶粒尺寸、孔隙率和内部应变等的影响可以归纳为介电常数或介电常数变化指数，这对未来高性能微波介电陶瓷的设计具有重要意义。
