High entropy induced superior weakly coupled relaxor phase and suppression interfacial polarization in (Bi0.3Na0.3Sr0.3Ba0.1)(Ti1-xNbx)O3 ceramics

Abstract

Dielectric ceramics with high configurational entropy (ΔS) and superior thermal stability in dielectric properties are tremendous promise materials for high performance of energy storage. However, interfacial polarization is the major challenge for superior energy storage performance. Herein, high-entropy and grain resistance strategy disrupts ferroelectricity long-range ordering in (Na_0.5Bi_0.5)TiO₃ ceramics via A/B-sites cation disorder. Lead free ceramics of (Bi_0.3Na_0.3Sr_0.3Ba_0.1)(Ti_1-xNb_x)O₃ (x = 0.0, 0.025, 0.05, 0.075 and 0.1) (abbreviate BBSNTNbx) were prepared using solid solution technique. The obtained results reveal that ΔS increased from 1.31R for x = 0.0–1.64R for x = 0.1 resulting in superior weakly coupled relaxor phase of BO₆. The imbalance of ion valances between donor Nb⁵⁺ and Ti⁴⁺ may force Ti⁴⁺ to become Ti³⁺ resulting in formation of Nb⁵⁺-Ti³⁺ ion pair leading to negligible remnant polarization (P_r). High entropy induced elevation the grain resistance and suppression interfacial polarization. As entropy increases from 1.31R to 1.64R, the energy storage efficiency (ƞ) increased from ∼83 % to 98 %. Furthermore, superior temperature stability across a broad temperature range 25–175 °C in both of W_rec and ƞ were investigated at high entropy. This research presents an effective method for designing NBT - based ceramics with suppression of interfacial polarization and ultra-high comprehensive energy storage performance.