Superior disrupting ferroelectric phase of (Ba Sr)Nb2O6 tungsten bronze structure via high entropy and cations disorder for ultrahigh breakdown strength
Marwa Kamal, Manal Mohammed Alhazmi, Abd El-razek Mahmoud
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 (E b ) and suppression interfacial polarization (IFPs). Herein, high-entropy strategy disrupts ferroelectricity long-range ordering in tungsten bronze structure of (Ba, Sr)Nb 2 O 6 ceramics via A/B-sites cation disorder. Hot pressing technique was performed to fabricate ((Ba 0.33−x Nd x )Sr 0.33 Ca 0.33 ))(Nb 2−x Ti x )O 6 , (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 0.23 Nd 0.1 )Sr 0.33 Ca 0.33 ))(Nb 1.9 Ti 0.1 )O 6 sintered ceramics. This research presents an effective method for designing tetragonal tungsten bronze dielectric ceramics with ultra-high breakdown strength performance.