摘要
利用高温固相反应制备了不同浓度Y^(3+)掺杂的δ-相Bi_(3)Nb_(1-x)Y_(x)O_(7)(x=0~0.60)化合物,并基于变温XRD、AC阻抗谱和Wager极化方法系统研究了其相结构转变、热膨胀和导电特性。归因于次晶格中O^(2-)/氧空位的有序/无序转变,较低Y^(3+)掺杂浓度(x≤0.3)形成的Type-Ⅱ型非公度准立方结构在高于临界掺杂浓度(x>0.30)时可转变为Type-Ⅲ型立方结构。基于变温XRD的热膨胀结果显示,Y^(3+)掺杂的Bi_(3)NbO_(7)化合物在低温区(t<540~℃)的热膨胀系数较低[(10.4~12.7)×10^(-6)K^(-1)],而在较高温区(540℃~950℃),由于无序分布氧离子扩散动性的增加,导致其热膨胀系数快速增大至24.0×10^(-6)K^(-1)。关于导电特性,Nb^(5+)位低价Y^(3+)掺杂不仅可以有效抑制Bi_(3)NbO_(7)的电子电导,还可大幅度提升离子电导率,其机制被认为与氧空位浓度增加相关。
The structural evolution,thermal behavior and conduction properties ofδ-phase Bi_(3)Nb_(1-x)Y_(x)O_(7)(x=0-0.60)materials prepared by solid state reaction are carefully investigated through X-ray thermodiffraction,AC impedance spectroscopy and Wager polarization method.Probably owing to the disorder distribution of O^(2-)/vacan‐cy in sublattice,the incommensurate Type Ⅱ phase observed in low-Y contained materials(x≤0.3)is found to transform to stable commensurate structure in high-Y contained samples with x0.30.The thermal expansion coefficient(TEC)of the Y substituted Bi_(3)NbO_(7)solid solutions are determined from X-ray thermodiffraction to be(10.4-12.7)×10^(-6) ℃^(-1)below 540℃,but rapidly increases to 24.0×10^(-6)K^(-1)in the temperature range 540-950℃,the mechanism is suggested to originate from the increase of diffusion mobility of disorder oxygen ions.The measurement of electrical properties shows that the partial substitution of Y ions at Nb sites can not only effectively suppress the electrical conductivity but also greatly enhance its ionic conductivity owing to the increase of oxygen vacancy concentration in lattice.
作者
王先平
WANG Xian-Ping(Key Laboratory of Materials Physics,Institute of Solid State Physics,HFIPS,Chinese Academy of Sciences,Hefei 230031,China)
出处
《安徽师范大学学报（自然科学版）》
2023年第3期205-210,共6页
Journal of Anhui Normal University(Natural Science)
基金
国家自然科学基金项目(U1967211,51971212)。
作者简介
王先平(1972-),男,安徽宿松县人,博士,研究员,博士生导师,安徽师范大学物理系1991级校友.主要研究方向为航天减振材料与固体电解质材料.
