Ca doping to enhance energy storage performance of lead‐free SrTi 0.99 Mn 0.01 O 3 thin films with low hysteresis

Abstract

Dielectric materials with excellent energy storage performance are urgently needed in advanced electrical power systems. We have reported that Mn2+-doped SrTiO3 thin films have high energy storage density. However, the thin films exhibit fat polarization-electric field hysteresis loops with high hysteresis, which is not conducive to greater energy storage performance. In this work, the Ca2+-doped Sr1-xCaxTi0.99Mn0.01O3 thin films are fabricated to construct slim polarization-electric field hysteresis loops with low hysteresis for obtaining excellent energy storage performance. Because Ca2+ can break the long-range ferroelectric order of SrTi0.99Mn0.01O3, the domain size decreases and the coupling of domains weakens, ultimately leading to low hysteresis. Moreover, doping Ca2+ can induce distortion of the octahedral [TiO6] to form local polarization regions. When doped an appropriate amount of Ca2+, local lattice distortion plays an important role in polarization behavior, which helps to enhance polarization. Meanwhile, the Ca2+-doped thin films also possess good insulation. Finally, the higher energy storage density of 63.9 J cm-3 is achieved in the Sr0.9Ca0.1Ti0.99Mn0.01O3 thin film. When the electric field is less than 4000 kV cm-1, the energy storage efficiency remains above 70%. Simultaneously, a wide working temperature range from -100℃ to 100℃ is also obtained.