Effect of oxygen vacancy on the dielectric relaxation characteristics of PMNT ceramics

Abstract

The as-sintered 0.68 Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 ceramics were firstly prepared using the Columbite technique and then further annealed in specific atmosphere. The effect of annealing atmospheres, e.g. O2, N2 and air conditions, on the phase structure, microstructure and dielectric properties of ceramics were systematically discussed. The obtained results suggested that, compared to as-sintered sample, there is no obvious difference in phase structure and microstructure for ceramics annealed in O2 atmosphere, showing pure perovskite structure and higher density. While the appearance of second pyrochlore phase and porosity can be found as sample was annealed in nitrogen or air condition. It is worth noting that the dielectric properties of ceramics are very sensitive to the annealing atmosphere and there is a significant increase in dielectric constant and decrease in dielectric loss as the PMNT ceramic was treated in O2 atmosphere, while sample annealed in N2 or air condition would show the opposite trend.