Sc^(3+)和Ru^(4+)联合取代BZN基陶瓷结构与介电性能的研究

Structure and Dielectric Properties of Sc^(3+)- and Ru^(4+)-doped BZN Based Ceramics

采用传统的固相反应法制备致密的Bi1.4Sc0.1ZnNb1.5-xRuxO7陶瓷样品,研究Sc3+,Ru4+共同替代对Bi2O3-Zn O-Nb2O5陶瓷的相结构、晶体化学特性和介电性能的影响。结果表明:当掺杂量x≤0.055 mol时,样品保持单一的立方焦绿石结构。当掺杂量x=0.055 mol时,X射线衍射峰强度变弱,峰形变宽。随着掺杂量的增加(0≤x≤0.04 mol),陶瓷样品的晶格常数a和A位离子与第7个氧O′平均键长R(A-O')逐渐减小,结晶化学参数键价和AV(O')[A4]增大,AV(O)[A2B2]减小,48f(O)偏移量ξ增加。室温下样品的介电常数随着掺杂量的增加而减小,介电损耗逐渐增加,介电松弛特征减弱。低温下样品呈现明显的弛豫现象,峰值温度Tm随着掺杂量的增加向高温方向移动。利用修正的Curie-Weiss(C-W)公式对样品εr-T曲线进行最小二乘法拟合,得出样品的弛豫度γ由R0样品的1.57减小到R40样品的1.33。

The dense Bi1.4Sc0.1Zn Nb1.5-xRuxO7 ceramics were prepared by traditional solid state reaction. The effect of Sc3＋ and Ru4＋ co-substitution on the phase structure, crystal chemistry and dielectric properties of Bi2O3-ZnONb2O5 were investigated. The results reveal that all doped samples show a pure α-BZN phase structure. When x=0.055 mol, the intensity of X-ray diffraction becomes weak and diffraction peaks broaden. With the increase of x, the lattice constant a and the average distance R（A-O＇） of the ceramics decrease. The bond valance calculation show that the AV（O＇）[A4] and oxygen ξ parameter of 48f（O） increase, but the AV（O）[A2B2] gradually decreases with the amount of Ru4＋ increasing. Meanwhile, the dielectric constant of samples decreases and the dielectric loss increases. The dielectric relaxation characteristics are weakened at room temperature while the relaxation behavior at low temperature is obvious. With increasing dopant, Tm shifts toward higher temperature. The εr-T curves of samples are fitted by the modified Curie-Weiss＇ s（C-W） formula. The calculations show that the degree of dielectric relaxation（γ） decreases from 1.57 to 1.33 when the Ru4＋ content increases from 0 to 0.04 mol.