Mn doping to enhance energy storage performance of lead-free 0.7NBT-0.3ST thin films with weak oxygen vacancies

摘要

In this study, we present an effective strategy to enhance energy-storage density by the Mn~(2+) substitution of Ti~(4+) into 0.7(Na_(0.5)Bi_(0.5))TiO_3-0.3SrTiO_3 (0.7NBT-0.3ST) relaxor ferroelectric thin films. The influence of Mn doping on the microstructures, ferroelectric properties, and energy-storage performances of the as-prepared films was investigated in detail. The results show that the values of electric break-down field strength and the difference values between maximum polarization and remnant polarization of the thin films are markedly improved by appropriate Mn doping. Owing to the high break-down field strength of 1894 kV/cm and the huge difference value between the maximum polarization and the remnant polarization of 56 μC/cm~2, a giant recoverable energy-storage density of 27 J/cm~3 was obtained for the 1 mol. % Mn-doped 0.7NBT-0.3ST thin film. These results indicate that the appropriately Mn-doped 0.7NBT-0.3ST thin films are promising for the application of advanced capacitors with high-energy storage density.