Ca doping to enhance energy storage performance of lead‐free SrTi _0.99 Mn _0.01 O ₃ thin films with low hysteresis

Dielectric materials with excellent energy storage performance are urgently needed in advanced electrical power systems. We have reported that Mn 2+ ‐doped SrTiO 3 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 Ca 2+ ‐doped Sr 1‐ x Ca x Ti 0.99 Mn 0.01 O 3 thin films are fabricated to construct slim polarization‐electric field hysteresis loops with low hysteresis for obtaining excellent energy storage performance. Because Ca 2+ can break the long‐range ferroelectric order of SrTi 0.99 Mn 0.01 O 3 , the domain size decreases and the coupling of domains weakens, ultimately leading to low hysteresis. Moreover, doping Ca 2+ can induce distortion of the octahedral [TiO 6 ] to form local polarization regions. When doped an appropriate amount of Ca 2+ , local lattice distortion plays an important role in polarization behavior, which helps to enhance polarization. Meanwhile, the Ca 2+ ‐doped thin films also possess good insulation. Finally, the higher energy storage density of 63.9 J cm ‐3 is achieved in the Sr 0.9 Ca 0.1 Ti 0.99 Mn 0.01 O 3 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.