1995 Volume 103 Issue 1202 Pages 1006-1010
Interface states at the grain boundaries in La, Mncodoped Ba0.5Sr0.5TiO3 ceramics have been characterized by using the isothermal transient capacitance method. The ceramic materials doped with 0.05, 0.06 and 0.075mol% Mn were used for the present experiments, all of which had the Curie point around -70°C and a room temperature resistivity>107Ω·m with a positive temperature coefficient of resistivity effect of more than seven orders of magnitude. The results indicate the existence of grain boundary interface states at a level of about 1.0eV below the conduction band edge in all the materials. On the other hand, it has been found from an analysis of the resistivity-temperature characteristics in the materials that barrier layers with a potential height of about 0.85eV were built at the grain boundaries above the temperature giving the maximum resistivity in the respective materials.
