STRUCTURAL AND HIGH-TEMPERATURE ELECTRICAL-PROPERTIES OF LAY-XSRXMNO3 PEROVSKITE MATERIALS

The phase constitution of Lay-xSrxMnO3 perovskite materials with 0 less than or equal to x less than or equal to 0.4 and 0.8 less than or equal to y less than or equal to 1 prepared by wet chemical techniques has been determined. Single phase La-deficient materials have been obtained at y=0.95 and x greater than or equal to 0.1 as well as for y greater than or equal to 0.8 and x less than or equal to 0.1. The observed variation of the lattice parameters leads to shrinking unit cell volume with Sr-content and with La-deficiency. Small polaron conduction has been observed for x<0.2, while for x greater than or equal to 0.2 metallic-like behaviour is observed for La-deficient materials. The electrical conductivity of Sr-free materials at 950 degrees C approaches 100 S/cm. The activation energy for conduction changes strongly with sintering temperature and composition of the specimen.