Synthesis and characterization of vanadium doped SrBi2Nb2O9 ferroelectric ceramics

Samples of compositions SrBi2VxNb2??xO9, x = 0.0, 0.1, 0.3, 0.5 were prepared by solid-state reaction technique using high purity oxides/carbonates. The samples were calcined at 700??C and sintered at 900??C. XRD diffractograms show that a single phase layered perovskite structure is formed in all the samples. Effect of partial substitution of pentavalent niobium ion (0.68A??) by smaller pentavalent vanadium ion ( 0.59A??) at B site on the microstructural, Curie temperature, dielectric constant and dielectric loss have been investigated. Partial substitution of Nb5+ by V5+ is observed to have a profound effect. Dielectric properties of SBVN were investigated from room temperature to 500 ??C and frequency of 100 Hz to 1 MHz. Dielectric constant values at their respective Curie points are observed to increase with increasing vanadium concentration. An overall increase in Curie temperature is also observed with increasing vanadium concentration. Strong relaxor like dielectric relaxation at the transition temperature have been observed. With increasing vanadium concentration the dielectric loss is observed to increase significantly. It is also observed that dielectric loss increases with increase in temperature.