Influence of vanadium doping on the processing temperature and dielectric properties of barium bismuth niobate ceramics

Barium bismuth vanadium niobate, BaBi₂(Nb_1-xV_x)₂O₉ (0 ≤ x ≤ 0.1) ceramics were fabricated from the powders prepared via solid state reaction route. The single phase layered perovskite structure was preserved up to 5 at% (x = 0.05) of vanadium. The addition of V₂O₅ substantially improved the sinterability associated with high density (96%) which was otherwise difficult in the case of pure BaBi₂Nb₂O₉ (BBN). The sintering temperature was significantly reduced from 1100 to 900 °C. The scanning electron microscopic (SEM) studies revealed the transformation of a porous microstructure to a well-packed platy grained with negligible inter-granular porosity. The dielectric constant of BBN ceramics at both room temperature and in the vicinity of the temperature of dielectric maximum (T_m) has increased significantly with increase in vanadium content and the loss remained almost constant. The T_m increased with increase in V₂O₅. For instance, there was an upward shift of about 25 °C in T_m for 5 at% (x = 0.05) vanadium-doped BBN. Interestingly, the diffuseness (γ) in the phase transition was found to decrease with increase in vanadium doping level.