KNb_(1-x)Mg_xO_(3-δ)的高温高压合成及输运性质研究  

TRANSPORT PROPERTIES OF KNb_(1-x)Mg_xO_(3-δ) SYNTHESIZED UNDER HIGH-TEMPERATURE AND HIGH-PRESSURE

作　　者：向军[1] 李莉萍[2] 

机构地区：[1]华东船舶工业学院基础学科系,江苏镇江212003 [2]吉林大学物理系,吉林长春130023

出　　处：《高压物理学报》2001年第4期297-303,298-303,共7页Chinese Journal of High Pressure Physics

摘　　要：采用高温高压法制备了KNb1-xMgxO3 -δ(x =0 .0～ 0 .3)氧离子导电材料 ,使用XRD、TG-DTA及交流复阻抗谱对样品的结构和离子导电性进行了表征。实验结果表明 ,高压降低了合成温度 ,合成的KNb1-xMgxO3 -δ系列固溶体与其母体KNbO3 一样都为正交钙钛矿结构 ,晶胞参数随掺杂量的增加而略微增大。固溶体KNb1-xMgxO3 -δ具有离子导电特征 ,通过拟合阻抗谱数据获得了该材料晶粒电导、晶界电导和体电导率与温度的关系。样品的晶界电阻较高 ,晶界效应十分明显 ,离子跳跃传导可能在其输运机制中占据主导地位。在x =0 .1附近 ,电导率达到最大值 ,70 0℃时为 1.2× 10 - 3 S·cm- 1。Single phase KNb 1- x Mg x O 3- δ (0.0～0.3)ion conductors were prepared using high temperature and high pressure method. The structural characteristics and ionic conductivities of KNb 1- x ·Mg x O 3- δ solid solutions were investigated by XRD,TG DTA and A C impedance spectra measurements. The XRD results show that all the products crystallized in a single orthorhombic perovskite structure.High pressure promotes the process of solid state reactions and the temperature for forming KNb 1- x Mg x O 3- δ solid solutions decreases under high pressure. With the increasing of doping amount, cell volume increases, which is related with substitution of Mg ion and existence of oxygen vacancies.Ionic conductivities measured by impedance spectroscopy showed that there is relatively high resistance along grain boundaries. The grain boundary effect is very obvious. By imitating the impedance data, the conductivities of grain,grain boundary and bulk were obtained, the temperature dependence of the conductivities of all the solid solutions is linear. The bulk conductivities of KNb 1- x Mg x O 3- δ solid solutions don't increase with the increasing of doping amount but achieve maximum at around x =0.1( σ =1.2×10 -3 S·cm -1 at 700℃).

关 键 词：KNb1-xMgxO3-δ 高温高压 离子电导 合成 输运性质 氧离子导电材料 铌酸钾 镁掺杂 

分 类 号：TM242[一般工业技术—材料科学与工程]