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

Abstract

Abstract 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 (Eb) 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 ((Ba0.33−xNdx)Sr0.33Ca0.33))(Nb2−xTix)O6, (BSCNNTX) (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 (Rg) and grain boundary (Rgb) completely suppressed at high ΔS resulting in pinched the interfacial polarization and oxygen vacancies effect. Superior elevation into activation energy (Ea) 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 Eb of 730 kV/cm in ((Ba0.23Nd0.1)Sr0.33Ca0.33))(Nb1.9Ti0.1)O6 sintered ceramics. This research presents an effective method for designing tetragonal tungsten bronze dielectric ceramics with ultra-high breakdown strength performance.