Single crystal growth and electrical properties of lanthanum- and gadolinium-doped BaTiO3

Single crystals of (Ba(0.96-x)Ln(x)Sr(0.04)) TiO3 (Ln=La, Gd) were grown over a composition range of x=0.001 to 0.03. Electrical resistivities of the single crystals were measured by the DC four-probe method. The temperature dependence of resistivities of these crystals changed from semiconductive to metallic at the Curie temperature (T-C). Although the room temperature resistivities of Gd-doped single crystals were independent of Gd concentration of 1 to 3 %, they decreased monotonically with increasing the dopant concentration after annealing in a reducing atmosphere.