Empowering energy storage performance of pyrochlore dielectrics through multicomponent octahedral interactions and nanodomain tuning

This study investigates the impact of B-site (Zn/Ti/Nb) compositional tuning on the energy storage properties of (Bi 1 . 5 Zn 0 . 5 )(Zn 0 . 5- x / 3 Ti x Nb 1 . 5-2 x / 3 )O 7 (BZTN) pyrochlore ceramics. By systematically varying the Ti content (x = 0, 0.3, 0.9, 1.5 mol%), we investigate the role of ZnO 6 , TiO 6 , and NbO 6 octahedra in governing domain structure and, consequently, dielectric and energy storage performance. X-ray diffraction and Raman spectroscopy confirm the formation of a single-phase pyrochlore structure, with Ti exclusively occupying the B-site, increasing B-site configurational entropy. Microstructural analysis reveals that Ti addition inhibits grain growth, influencing domain configuration. Dielectric measurements identify BZTN09 ( x = 0.9) as the optimal composition, achieving a balanced dielectric permittivity, low loss, and excellent temperature stability. Notably, BZTN09 exhibits a high charge-discharge efficiency (97 %) and stable energy storage performance up to 200 °C. Positive-up-negative-down (PUND) measurements indicate that BZTN09 possesses more reversible polarization behavior than other compositions. This enhancement is attributed to the formation of highly switchable polar nano-regions (PNRs) stabilized by a small fraction of ZnO 6 octahedra. These findings highlight the critical role of compositional control in optimizing domain structure within pyrochlore dielectrics, advancing the development of high-performance energy storage materials for capacitor applications.