Impact of annealing process on the properties of 0.85Pb(Sc0.5Ta0.5) O3-0.15PbTiO3 ceramics

We have synthesized a ceramic sample 0.85Pb(Sc0.5Ta0.5)O3-0.15PbTiO3 [0.85PST-0.15PT] of perovskite structure by using a conventional solid-state reaction method. Systematic impact of annealing time (AT) is studied methodically for comprehending the ferroelectric and dielectric properties, as well as electrocaloric effect and energy harvesting performance. After 40 h of AT and using the electric field of 40 kV/cm on 0.85PST-0.15PT, we have achieved maximum ferroelectric polarization (P = 46.9 mu C/cm2), energy capture performance (W = 0.542 J/cm3), and large positive electrocaloric effect (Delta T -1.63 K and Delta S -1.23 J/(K.kg)). Additionally, we also achieved high dielectric constant (e = 23,350) and low dielectric loss (tan delta = 0.039) at the frequency of 1 Hz. As compared to an unannealed situation, the results on ceramic sample with 40 h of AT have revealed increase in P, e, Delta T, Delta S, and W by 36%, 27%, 37%, 12% and 14%, respectively. Optimal values of AT differed radically for achieving the highest performance in each category. The best performance of energy storage (Wenergy -0.638 J/cm3) and energy loss (Wloss -0.498 J/cm3) densities are achieved with the AT of 30 h. The performance of 0.85PST-0.15PT sample increased gradually with the increase of AT until it attained the highest value and then decreased by further increasing AT - exhibiting a peak distribution. Our investigations have provided valuable insights of optimizing the performance of 0.85PST-0.15PT ceramic system through annealing.