Structural, thermal and electrical properties of Ce-doped SrMnO3

The Sr1-xCexMnO3-alpha system (0 less than or equal to x less than or equal to 0.5) was investigated with respect to its structural, thermal and electrical properties. Although un-doped SrMnO3 has the perovskite structure above 1400 degrees C, the structure is unstable at room temperature. However, partial substitution of Ce for Sr in SrMnO3 stabilizes the perovskite structure down to room temperature. Single phase perovskite is obtained for 0.1 less than or equal to x less than or equal to 0.3 in Sr1-xCexMnO3-alpha, and it remains stable even following heat treatment at 800 degrees C for 100 h. The dependence of the electrical conductivity on temperature was measured from room temperature to 1000 degrees C in air. Ce doping dramatically enhanced the electrical conductivity of SrMnO3. Sr0.7Ce0.3MnO3-alpha exhibits a higher conductivity (290 S.cm(-1) at 1000 degrees C) than that of La0.8Sr0.2MnO3 (LSM, about 175 S.cm(-1)) and remains n-type over the whole range of temperature examined. The thermal expansion coefficients in the system were nearly constant with values ranging between 1.24 x 10(-6) and 1.01 x 10(-6)cm/cm.K for temperatures of 50 degrees C to 1000 degrees C.