新型氧离子导体La_2Mo_(1.8)Ga_(0.2)O_9陶瓷的合成及其电性能  

Synthesis and Electrical Properties of La_2Mo_(1.8)Ga_(0.2)O_9 Ceramics as a New Type of Oxide-ion Conductor

作　　者：许睿[1] 潘博[1] 张峰[1] 马桂林[1] 仇立干[2] 

机构地区：[1]苏州大学化学化工学院江苏省有机合成重点实验室,苏州215123 [2]盐城师范学院化学系,盐城224002

出　　处：《化学学报》2006年第24期2442-2446,共5页Acta Chimica Sinica

基　　金：国家自然科学基金(No.20171034);江苏省教育厅指导计划(No.04KJD150218)资助项目.

摘　　要：通过高温固相合成法首次合成了La2Mo1.8Ga0.2O9陶瓷样品.粉末XRD结果表明,该样品为单一立方相La2Mo2O9结构.以陶瓷样品为固体电解质、多孔性铂为电极,采用交流阻抗谱、气体浓差电池、氧泵等方法研究了样品在600～1000℃下各种气氛中的离子导电特性.结果表明,氧浓差电池电动势的实测值与理论值吻合得很好,氧离子迁移数为1,表明该陶瓷样品在该温度下氧气气氛中为一纯氧离子导体;氧泵(氧的电化学透过)实验结果进一步证实了该样品在氧气气氛中为一纯氧离子导体;在氧分压p(O2)=10-5～105Pa的高氧分压气氛中,电导率与氧分压变化基本无关,表明在该氧分压范围内样品为纯离子导体,这与氧浓差电池电动势测定结果相吻合;在低氧分压为10-5～10-15Pa范围内,总电导率随氧分压降低而稍有升高,表明在该氧分压范围样品为氧离子与电子的混合导体;在600～1000℃下氧离子电导率>10-2S?cm-1,显著高于母体La2Mo2O9的氧离子电导率,1000℃时的氧离子电导率为0.07S?cm-1.The sample of La2Mo1.8Ga0.2O9 ceramics was prepared for the first time by high-temperature solid-state reaction. X-ray powder diffraction pattern shows that the sample is of a single cubic phase of La2Mo2O9. Using the ceramics as solid electrolyte and porous platinum as electrodes, the ion conduction properties of La2Mo1.8Ga0.2O9 ceramics were investigated by means of ac impedance spectroscopy, oxygen concentration cell and oxygen pump （electrochemical oxygen permeation） at 600～1000 ℃ in various atmospheres. The observed values of oxygen concentration cell coincided with theoretical ones perfectly, indicating that the conduction in the ceramics was purely oxide-ionic with oxygen ion transference number of 1 under oxygen atmosphere over the whole temperature range of 600～1000 ℃. The electrochemical oxygen permeation rate determined was in accordance with the theoretical one calculated from Faraday＇s law, verifying direct experimentally the oxide-ionic nature of the conduction under oxygen atmosphere. Under high oxygen partial pressure [p（O2）= 10^-5～10^5 Pa], La2Mo1.8Ga0.2O9 was almost a pure ionic conductor, which was consistent with the result by means of oxygen concentration cell. Whereas at low oxygen partial pressure [p（O2）= 10^-5～10^-15 Pa], the sample exhibited a mixed ionic and electronic conduction. The ionic conductivities of this ceramics are higher than 10^-2 S·cm^-1, which is obviously superior to the matrix La2Mo2O9 over the temperature range of 600～1000 ℃. The ceramics is shown to have the oxide ionic conductivity of 0.07 S·cm^-1 at 1000 ℃.

关 键 词：La2Mo1.8Ga0.2O9 La2MO2O9 氧离子导体 氧浓差电池 氧泵 

分 类 号：TQ174.1[化学工程—陶瓷工业]