Effects of structural characteristics on microwave dielectric properties of (1−x)CaWO4 –xLaNbO4 ceramics
Effects of structural characteristics on microwave dielectric properties of (1−x)CaWO4 –xLaNbO4 ceramics
复制标题
DOI：
10.1007/s10832-006-8571-7
复制
发表时间：
2006-12
影响因子：
1.7
通讯作者：
E. Kim;S. Kim
中科院分区：
文献类型：
--
作者：
E. Kim;S. Kim
研究了（1−x）CaWO 4-xLaNbO 4陶瓷的微波介电性能随LaNbO 4含量（0.0 ≤x≤ 0.5）的变化规律。当tox= 0.35时，得到了单一的四斜晶系白钨矿结构，然后检测到白钨矿和辉砷铅矿结构的混合物相。随着LaNbO 4含量的增加，由于ABO 4白钨矿结构中氧键价的降低，由Clausius-Mosotti方程计算的介电极化率与由介电极化率加和规则计算的理论值的偏差减小.随着LaNbO 4含量的增加，材料的介电常数（K）和谐振频率温度系数（TCF）增加，这是由于氧键价态的降低，Q值与晶胞的原子堆积率和晶粒尺寸有关。典型地，对于含有0.3 mol LaNbO 4的样品，在1150 oC下烧结3 h，获得了K= 13.3，Qf = 50，000 GHz和TCF = −8.7 ppm/oC。
Dependences of microwave dielectric properties on the structural characteristics of (1−x)CaWO4–xLaNbO4ceramics were investigated as a function of LaNbO4content (0.0 ≤x≤ 0.5). A single phase with tetragonal scheelite structure was obtained up tox= 0.35, and then the mixture phases with scheelite and fergusonite structure were detected. With the increase of LaNbO4, the deviation of the observed dielectric polarizabilities calculated by the Clausius-Mosotti equation from the theoretical values calculated by the additivity rule of dielectric polarizability, was decreased due to the decrease of oxygen bond valence in ABO4scheelite structure. Dielectric constant (K) and temperature coefficient of resonant frequency (TCF) were increased with LaNbO4content due to the decrease of oxygen bond valence.Q ⋅ fvalue was dependent on the atomic packing fraction of unit cell as well as the grain size. Typically,K= 13.3,Qf= 50,000 GHz andTCF= −8.7 ppm/oC were obtained for the specimens with 0.3 mol of LaNbO4sintered at 1150oC for 3 h.