湿化学法制备钙钛矿型La_（1－x）Sr_xMnO_3的电学性能及其晶体学研究

On the Crystallology and Electrical Properties of Perovskite-Type Ll_(1-x)Sr_xMnO_3 Prepared by the Coprecipition Process

采用湿化学法制备了粒度在０．２～０．８μｍ范围的钙钛矿型Ｌａ（１－ｘ）Ｓｒ＿ｘＭｎＯ＿３粉末，用室温和高温Ｘ衍射法测定其晶体结构。发现其在１２００℃高温发生了四方→立方的相变；制备的粉末粒度与水浴温度有一定的关系，在室温时电阻率在６．０×１０￣（－３）～６．９×１０￣（－３）Ω·ｃｍ范围内，在温度大于４５０℃后，随着温度的升高，电阻率亦升高。

Perovskite-type(La(1-x)Sr_xMnO3)powders in the range of grain size of 0.2～1.8μm havebeen prepared by the coprecipitation process and the crystalline structure and electrical prop-erties of the powders have been investigated. At certain bathing temperatures and pH val-ues,ultra-fine ceramic powders can be obtained. The least square method is used to calculatethe lattice constants; The structure of La_(1-x)Sr_xMnO_3 remains unchanged with an increase ofthe Sr content,but the lattice constant a(h)decreases although c(h)remains constant. It hasbeen found that La_(1-x)Sr_xMnO_3(x=0.1,0. 2)undergoes a tetragonal-cubic phase trasition at1 200 ℃, The average resistivity of La_(0.5)Sr_(0.5)MnO_3 is 6. 4×10￣(-3)Ω·cm at room temperatureand it increases with the temperature when the temperature exceeds 450℃. Experimental re-sults show that the material will be good for making SOFC electrodes,