CaTiO3基微波介质陶瓷的频率温度稳定性

通过对克劳修斯-莫索蒂方程的近似, 分析了钙钛矿结构微波介质陶瓷频率温度系数 (τ_f) 的主要影响因素, 发现改变材料介电响应中离子位移极化和电子位移极化的比例, 可调节频率温度系数的正负与大小. 通过电子结构计算和容忍因子分析, 预测引入(Zn_1/3Nb_2/3)⁴⁺对具有正温度系数 的CaTiO₃进行B位取代将提高材料电子极化响应比例, 调节τ_f由正变负. 采用偏铌酸盐为前驱体, 通过固相反应法合成了Ca(Zn_1/3Nb_2/3)_xTi_(1-x)]O₃钙钛矿结构陶瓷, 并对其进行结构分析和性能测试, 实验结果与理论分析一致, 获得了具有近零频率温度系数的Ca(Zn_1/3Nb_2/3)_0.7Ti_0.3]O₃介质陶瓷材料. 关键词： B位复合钙钛矿陶瓷 谐振频率温度稳定性 极化机理 6八面体倾斜')" href="#">BO₆八面体倾斜

Resonant frequency temperature stability of CaTiO3 based microwave dielectric ceramics

The determinants of resonant frequency temperature coefficient (τ_f) have been analyzed by the approximate treatment of Clausius-Mossotti equation. It is suggested that the value of τ_f can be adjusted by changing the contribution proportion of ionic polarization or electronic polarization for the dielectric constant. Results of electronic structure calculation and tolerance factor analysis show that B-site substitution of CaTiO₃ with (Zn_1/3Nb_2/3)⁴⁺ could turn the value of τ_f from positive to negative, by enhancing the covalency in the BO₆ octahedron and improving the contribution proportion of electronic polarization. Ca(Zn_1/3Nb_2/3)_xTi_(1-x)]O₃ dielectric ceramics were prepared by solid-state reaction method with niobate as precursor. Results of structure analysis and property measurement conform to the theoretical analysis. The Ca(Zn_1/3Nb_2/3)_0.7Ti_0.3]O₃ dielectric ceramic with near-zero τ_f was obtained.
Keywords： B-site complex perovskite ceramics resonant frequency-temperature stability polarization 6octahedron tilting')" href="#">BO₆octahedron tilting