Phase tuning in lanthanum doped lead zirconate titanate near morphotropic phase boundary using chemical co-precipitation route and their dielectric properties

Abstract

Lanthanum doped PZT namely Pb_1−xLa_xZr_0.6Ti_0.4O₃ x = 0.06, 0.07 and 0.08 (PLZT) were prepared by chemical co-precipitation method. The X-ray diffraction analysis confirms the tetragonal phase formation for all the compositions of PLZT ferroelectrics whereas x = 0.07 composition show co-existence of tetragonal and rhombohedral phase. From SEM morphology results it is seen that the as doping concentration of La increases the average grain size also increases. Maximum value of dielectric constant obtained for x = 0.07 composition supplements co-existence of tetragonal and rhombohedral phase. Dielectric result shows the phase transformation from ferroelectric to paraelectric at transition temperature (T_c). As frequency increases the dielectric constant decreases. Raman spectroscopic analysis has also been carried out to support phase tunability in the samples under investigation. The highest value of saturation polarization (Pmax) = 15.861 µC/cm² and maximum piezoelectric coefficient (d₃₃) = 256 pC/N obtained for PLZT x = 0.07 for the sample sintered at 1200 °C.