Effect of Lanthanum substitution on ferroelectric properties of Niobium doped PZT ceramics

Lead zirconate titanate (PZT) based piezoelectric ceramics with a composition of Pb1−xLax(Zr1−yTiy)0.975Nb0.025O3 where x = 0.02–0.08 and y = 0.45 were studied using conventional mixed-oxide route and sintered at 1270 °C. The specimens were fabricated and studied to understand the effect of Lanthanum substitution on the microstructure and the ferroelectric properties. The modified composition with 8 mol% of La3+ substitution has shown dielectric constant (ε) = 1978 at 1 kHz, planar coupling coefficient (Kp) ≈ 0.58 and loss factor (tanδ) ≈ 0.014 at room temperature. Results revealed that La3+ substitution in Nb5+ doped PZT increases the dielectric and piezoelectric constants and reduces dielectric loss against La3+ free PZT-Nb5+ composition. The microstructural analysis of the modified composition shows the refinement of the grain in addition of La3+.