Ultrahigh electric breakdown strength,excellent dielectric energy storage density,and improved electrocaloric effect in Pb-free (1-x)Ba(Zr0.15Ti0.85)O3-xNaNbO3 ceramics

In this study, NaNbO₃ (NN) was introduced into Ba(Zr_0.15Ti_0.85)O₃ (BZT) to form a solid solution with relaxor ferroelectric characteristics. The dielectric breakdown strength (BDS) of the specimen with 6 mol.% NN reached 680 kV/cm, the corresponding recoverable energy storage density (W_rec) was 5.15 J/cm³, and the energy storage efficiency (η) was 77%. The dissolution of Na ⁺ ions at the A position and Nb⁵⁺ ions at the B position of the perovskite structure reduced the concentration of oxygen vacancies in the lattice and compensated for defects. The doped ceramics exhibited lower dielectric loss and better thermal stability: the W_rec value was 2 ± 1% J/cm³ at 30–120 °C. In particular, in the 0.02NN ceramics, a ΔT of 1.81 K was achieved at 130 kV/cm, and the operating temperature zone expanded with the increase in doping concentration. The introduction of NN resulted in BZT ceramics that possess excellent energy storage performance and electrocaloric effect properties.