Influence of Sr-Addition on the Semiconducting Behavior of La-Doped BaTiO₃ Ceramics

Abstract

La-doped (Ba, Sr)TiO₃ ceramics were prepared by using high purity starting materials to clarify the influence of Sr addition on the semiconducting behavior of BaTiO₃. No sintering aids such as SiO₂ and excess TiO₂ were used. Resistivity at room temperature, grain growth and Curie temperature (T_C) were studied as functions of Sr content. The addition of Sr within a range of 20mol% enhanced grain growth, and the room-temperature resistivity decreased with increasing Sr content. The decreasing rate of T_C in Ba_0.8-xLa_xSr_0.2TiO₃ was smaller than that in Ba_1-xLa_xTiO₃ with La content (x), but the total amount of La incorporated into the grains is considered not to be noticeably influenced by Sr addition. The present result may suggest that the addition of Sr increases the ratio of the concentration of La incorporated into the lattice compensated with free electrons to the total content of La doped. The addition of further amounts of Sr caused an increase in the total resistivity.