Doping mechanisms and electrical properties of La-doped BaTiO3 ceramics

The electrical properties of Ba1-xLaxTi1-x/4O3 ceramics where x less than or equal to 0.20 were investigated by impedance spectroscopy after heat treatment in O-2, Ar and air at 1350 degreesC, Samples heated in O-2, were electrically insulating with very high maximum permittivities, similar to 25,000 at x=0.06 and exhibited significant 'relaxor-type' behaviour at x=0.10. Samples heated in Ar were semiconducting for all x whereas air heated samples were electrically inhomogeneous. Semiconductivity in these materials is attributed to oxygen loss as opposed to La-donor doping. (C) 2001 Elsevier Science Ltd. All rights reserved.