La^(3+)掺杂对焦绿石型Bi_2O_3—ZnO-Nb_2O_5陶瓷结构和介电性能的影响  

Effect on Structure and Dielectric Properties of La^(3+) Doped Bi_2O_3—ZnO-Nb_2O_5 Based Ceramics

作　　者：张倩[1] 丁士华[1] 宋天秀[1] 曾卓玮[1] 钟祥清[1] 

机构地区：[1]西华大学材料科学与工程学院,成都610039

出　　处：《硅酸盐学报》2014年第6期729-733,共5页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(11074203);教育部春晖计划(Z2011077);西华大学研究生创新基金(YCJJ201303;YCJJ201306)资助项目

摘　　要：采用固相反应法制备(Bi1.5LaxZn0.5—x)(Zn0.5+xNb1.5—x)O7(BZNL,x=0.01~0.07mol)焦绿石型陶瓷。利用X射线衍射仪和高阻抗分析仪(LCR)对样品结构、结晶化学特性与介电性能进行表征。结果表明:所有陶瓷样品均保持单一的立方焦绿石相;随La3+替代量的增加,陶瓷样品中A位阳离子与8b位O′的平均键长r(O′—A)从0.228 36nm增加到0.228 46nm;键价和AV(O′)[Bi3La]、AV(O′)[Bi2ZnLa]、AV(O′)[Bi2La2]、AV(O′)[BiZn2La]随之减小;48f位氧的坐标ζ从0.028 27nm增加到0.029 03nm;样品的介电弛豫峰值温度Tm向低温方向移动,峰值介电常数εm依次减小,当替代量x=0.07mol时,介电弛豫峰值温度Tm降低到最低温度(—107.4℃),峰值介电常数εm为136.35。样品介电弥散性的增强与八面体结构的转变有关。（Bi1.5LaxZn0.5-x） （Zn0.5＋xNb1.5-x）O7 （BZNL,x-0.01-0.07 mol） ceramic was prepared via solid phase reaction.The effect of La3＋ on the structure,crystal chemistry and dielectric properties was investigated by Xray diffraction and a high precision LCR meter.The results reveal that all the samples exhibit a single cubic pyrochlore phase.The average distance R（o＇-A）of BZNL ceramics increases from 0.228 36 to 0.228 46 nm,the bond valence sums AV（O＇） [Bi3La],AV（O＇） [Bi2ZnLa],AV （O＇） [Bi2 La2],AV（O＇） [BiZn2La] all decrease,the ζ coordinate of the 48f oxygen increases from 0.028 27 to 0.029 03 nm,the temperature of maximum dielectric constant Tm shifts towards lower temperature and the maximum value of dielectric constant εm decreases when La3＋ content increases.When x 0.07 mol,the temperature of maximum dielectric constant Tm decreases to the lowest temperature （107.4 ℃）,and the maximum dielectric constant εm is 136.35.The increase of relaxation behavior could be closely related to the change of octahedral.

关 键 词：立方焦绿石 结晶化学 介电弛豫 

分 类 号：TM22[一般工业技术—材料科学与工程]