Sm-doping driven state-phase transition and energy storage capability in lead-free Ba(Zr0.35Ti0.65)O3 films

The stability of high energy-storage performance dielectric-film capacitors with respect to frequency, temperature, and cycle number is very essential for developing energy-storage devices. Here, the impact of Sm-doping concentration on the structure and energy-storage stability of lead-free Ba(Zr0.35Ti0.65)O3 (BZT) films have been systematically investigated. The formation of random electric fields, due to the co-occupying heterovalent ions of Sm3+/Ti4+ at the B-sites, serves to enhance the breakdown strength and reduce the polarization reversibility. As a result, an enhanced recoverable energy-storage density of 133.3 J/cm3 and an excellent energy efficiency of 89.4% are simultaneously achieved in 25 mol% Sm-doped BZT films (BZT-Sm25) under an applied electric field of 7.0 MV/cm. In addition, the BZT-Sm25 films also exhibit outstanding energy-storage performance stability over a large frequency-range of 1–1000 Hz, a wide temperature-range of 25 °C–200 °C, and beyond 1010 switching-cycles, even under a high electric field of 6 MV/cm. These achieved results demonstrate that the Sm-doped BZT films are promising candidates for the development of high-performance and environmentally friendly energy-storage devices.