Dielectric loss study of oxygen vacancies and domain walls in Sr2Bi4-x/3Ti5-xVxO18 ceramics

An investigation on the ferroelectric and dielectric properties of vanadium-doped Sr2Bi4Ti5O18 ceramics was presented. The ferroelectricity of Sr2Bi4-x/3Ti5-xVxO18 samples (x=0, 0.003, 0.0048, 0.018, 0.048, and 0.096) was obviously improved by vanadium doping. The dielectric property measurement indicated that the Curie temperature was unaffected by vanadium doping, while it displayed a strong dependence of their dielectric loss on vanadium content. One dielectric loss peak around 230degreesC related to oxygen vacancies was reduced with doping. Another peak which was just a few degrees below the Curie point and ascribed to viscous motion of domain walls declined drastically with the increase of vanadium content. Those results suggested that the substitution of a small amount of V5+ for Ti4+ reduced the concentration of oxygen vacancies significantly under the restriction of charge neutrality. This led to the weakening of domain pinning and the increasing of the mobility of domain walls, which would be responsible for the increase in 2P(r). (C) 2004 American Institute of Physics.