Superior disrupting ferroelectric phase of (Ba Sr)Nb2O6 tungsten bronze structure via high entropy and cations disorder for ultrahigh breakdown strength

High configurational entropy (ΔS) dielectric ceramics possess a unique competitive advantage in electronic applications due to their high-power density and excellent reliability. However, their development with superior energy storage density require high breakdown strength (E_b) and suppression interfacial polarization (IFPs). Herein, high-entropy strategy disrupts ferroelectricity long-range ordering in tungsten bronze structure of (Ba, Sr)Nb₂O₆ ceramics via A/B-sites cation disorder. Hot pressing technique was performed to fabricate ((Ba_0.33-xNd_x)Sr_0.33Ca_0.33))(Nb_2-xTi_x)O₆, (BSCNNT_X) (x = 0.0, 0.05 and 0.1) in order to reduce the consumption energy during polyvinyl alcohol (PVA) burning. The obtained results reveal that ΔS increased from 1.09R for x = 0.0 to 1.49R for x = 0.1. The miss-matching between resistance of grain (R_g) and grain boundary (R_gb) completely suppressed at high ΔS resulting in pinched the interfacial polarization and oxygen vacancies effect. Superior elevation into activation energy (E_a) was achieved at high ΔS where it increased from 0.041 eV at ΔS = 1.09R to 0.18 eV at ΔS = 1.49R attributed to superior weakly coupled of relaxor phase. This cascade effect results in outstanding breakdown strength ultimately achieving a E_b of 730 kV/cm in ((Ba_0.23Nd_0.1)Sr_0.33Ca_0.33))(Nb_1.9Ti_0.1)O₆ sintered ceramics. This research presents an effective method for designing tetragonal tungsten bronze dielectric ceramics with ultra-high breakdown strength performance.