Ti掺杂Sm_(0.9)Sr_(0.1)AlO_3陶瓷的结构及电性能

Structure and electrical properties of Ti-doped Sm_(0.9)Sr_(0.1)AlO_(3-δ) ceramics

基于有机凝胶法分别在空气和还原气氛(75%Ar/25%H2)下制备了Sm0.9Sr0.1Al0.9Ti0.1O3钙钛矿结构陶瓷,使用X射线衍射、扫描电子显微镜和交流复阻抗等技术对样品进行了表征,研究了制备气氛、测量气氛以及Ti掺杂对材料结构特征和电性能的影响.结果表明:Ti对Al的取代导致晶格常数增大,同时还明显提高了陶瓷体的致密度;还原气氛下制备的Sm0.9Sr0.1Al0.9Ti0.1O3陶瓷由于晶粒发育不充分,其致密度相对于空气中制备的样品有所降低,该陶瓷在还原气氛中的电导率较空气中高约2～3个数量级,比空气气氛下制备的Sm0.9Sr0.1Al0.9Ti0.1O3陶瓷在空气中的电导率高约3～4个数量级,在800℃以下高于未掺Ti的Sm0.9Sr0.1AlO3陶瓷在空气中的电导率,这些差别可以从不同体系中带电缺陷的类型及数量的变化来进行理解.

Sm0.9Sr0.1Al0.9Ti0.1O3 ceramics with a perovskite-type structure were prepared by organic-gel method combined with high temperature sintering process under air and reducing atmospheres, respectively. The samples were characterized by means of X-ray diffraction, scanning electron microscope, AC complex impedance, etc. The effects of the preparation atmosphere, measuring atmosphere and Ti doping on the structural characteristic and electrical properties of the samples were investigated. The results slaow that the substitution of Ti for A1 leads to an increase in the lattice constant and still obviously enhances the density. Sm0.9Sr0.1Al0.9Ti0.1O3 ceramic prepared under reducing atmosphere exhibits a relatively low density compared to the sample prepared under air atmosphere due to the insufficiency of grain growth under reducing atmosphere. The electrical conductivity in reducing atmosphere is about 2 - 3 orders of magnitude larger than that in air for Sm0.9 Sm0.9Sr0.1AlO3 prepared under reducing atmosphere and is around 3 -4 orders of magnitude greater than the value in air for the sample prepared under air atmosphere, and furthermore its value is higher than that of Ti-undoped Sm0.9Sr0.1AlO3 ceramic in air at the measuring temperatures below 800 ℃. These differences in electrical properties can be explained in terms of the changes of the amount and type of charged defects in different materials.