Structural phase transition in La-substituted Pb[(Yb1/2Nb1/2)(0.88)Ti-0.12]O-3 relaxor system

Abstract

We have investigated the effect of substitution of La2O3 + Yb2O3 to the perovskite solid solution near the composition (PbYb1/2Nb1/2O3)(0.88)-(PbTiO3)(0.12) in the chemical formula (1-x)[(PbYb1/2Nb1/2O3)(0.88) (PbTiO3)(0.12)]-xLaYbO(3). When x = 0.0 and x = 0.01; these solid solution have partially disordered pseudocubic structure and behave as a ferroelectric relaxer. For x greater than or equal to 0.02, the character of phase transition changes from a ferroelectric relaxer type to an antiferroelectric one and the transition temperature surprisingly increases with LaYbO3 addition. In this composition range, the solid solution displays a sharp antiferroelectric transition. The effect on the tendency toward antiferroelecticity with increasing LaYbO3 content is displayed in restoring of the superlattice reflections due to antiferroelectric order. From the structural study of ceramic specimen having various PbTiO3 and LaYbO3 concentration, we have constructed a portion of phase diagram of pseudoternary PbYb1/2Nb1/2O3-PbTiO3-LaYbO3 system.