An investigation was made of the ferro-electric and dielectric properties of V-doped Sr2Bi4Ti5O18 ceramics. The ferro-electricity of Sr2Bi4–x/3Ti5–xVxO18 samples (x = 0, 0.003, 0.0048, 0.018, 0.048 or 0.096) was clearly improved by V-doping. The dielectric measurements indicated that the Curie temperature was unaffected by V-doping, but revealed a strong dependence of dielectric loss upon V content. One dielectric loss peak, around 230C, which was related to O vacancies was reduced by doping. Another peak which was just a few degrees below the Curie point, and was attributed to the viscous motion of domain walls, decreased sharply with increasing V content. The results suggested that the substitution, of a small amount of V5+ for Ti4+, significantly reduced the concentration of O vacancies within the restrictions of charge neutrality. This led to a weakening of domain pinning and an increasing mobility of domain walls.

Dielectric Loss Study of Oxygen Vacancies and Domain Walls in Sr2Bi4–x/3Ti5–xVxO18 Ceramics. W.P.Lu, X.Y.Mao, X.B.Chen: Journal of Applied Physics, 2004, 95[4], 1973-6