新型LaAlO_3基混合导体的制备和导电性能

Preparation and Electrical Properties of a New LaAlO_3-Based Mixed Conductor

以高温固相反应法制备了混合导电性陶瓷La_(0.8)Sr_(0.2)Al_(0.97)Zn_(0.03)O_(3-σ)(LSAZ),并使用XRD、SEM和交流复阻抗技术对样品的物相、微观形貌、电导性能进行了表征。粉末XRD结果表明,LSAZ陶瓷为单一的六方钙钛矿型结构。采用氧浓差电池测定了LSAZ在700～900℃范围内的离子迁移数,研究了其氧离子导电特性。结果表明,LSAZ在空气气氛中是一个氧离子和电子空穴的混合导体,氧离子迁移数在0.6左右,并随温度的升高而逐渐增大。在850℃时,LSAZ的总电导率达到1.0×10^(-2)S/cm,氧离子电导率为6.4×10^(-3)S/cm,氧离子电导活化能为0.96 eV。

Mixed conduction ceramic La0.8Sr0.2Al0.97Zn0.03O3-δ （LSAZ） was prepared by high temperature solid-state reaction method. The structure, micro morphologies and electrical properties of LSAZ were characterized by XRD, SEM and AC complex impedance spectrum. The powder XRD analysis showed that the crystal structure of LSAZ was single hexagonal phase. Oxide-ionic conducting characteristics of LSAZ have been investigated by mean of oxygen concentration cell between 700 ℃ and 900 ℃. It was found that LSAZ was a mixed conductor of oxide ion and hole in air. The oxygen ionic transference numbers of LSAZ were around 0.6 in the temperature region, and slightly increased with increasing temperature. The sintered LSAZ sample exhibited a higher total electrical conductivity of 1.0×10^-2 S/era in air at 850℃ than La0.8Sr0.2AlO3-δ （LSA）. According to oxide ionic transference numbers measured in air, the relative contribution of ionic and electronic conduction were separated. The results showed that LSAZ had an oxide ionic conductivity of 6.4 × 10^-3 S/cm at 850 ℃ and activation energy for oxygen ionic conduction of 0.96 eV.