| Summary: | The characteristic transition from ferroelectric (FE) to ergodic relaxor (ER) state in (Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO<sub>3</sub> (BNT) based lead-free ceramics provides an efficient approach to bring a highly ordered phase back to a disordered one. It would be rational to utilize this transition to improve relevant non-piezoelectric properties based on domain decomposition. In this work, different La contents were introduced to 0.93(Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO<sub>3</sub>-0.07Ba(Ti<sub>0.945</sub>Zr<sub>0.055</sub>)O<sub>3</sub> ceramics (BNT-BZT-<i>x</i>La) to induce evolution of ergodic degree. The results reveal that with increasing La content, both the FE-ER transition temperature <i>T</i><sub>F-R</sub> and depolarization temperature <i>T</i><sub>d</sub> shift towards room temperature, implying a deepened ergodic degree. By modulation of ergodic degree, thermally stimulated depolarization current experiment shows a higher current density peak, and corresponding pyroelectric coefficient increases from 2.46 to 2.81 μC/(cm<sup>2</sup>∙°C) at <i>T</i><sub>d</sub>. For refrigeration, the indirect measurement demonstrates the Δ<i>T</i> maximum increases from 1.1 K to 1.4 K, indicating an enhanced electrocaloric effect. Moreover, the optimized energy storage effect is observed after La doping. With appearance of “slimmer” <i>P</i>-<i>E</i> loops, both calculated recoverable energy storage density <i>W</i><sub>rec</sub> and storage efficiency <i>η</i> increase to 0.23 J/cm<sup>3</sup> and 22.8%, respectively. These results denote La doping conduces to the improvement of non-piezoelectric properties of BNT-based ceramics in a certain range. Therefore, La doping should be an adopted modification strategy for lead-free ceramics used in areas like refrigerator and pulse capacitors.
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