Achieving ultrahigh energy storage performance in bismuth magnesium titanate film capacitors via amorphous-structure engineering

Abstract

Pure perovskite Bi(Mg_0.5Ti_x)O₃ (abbreviated as BMT_x) thin films are successfully fabricated on Pt/Ti/SiO₂/Si substrates by a sol–gel method, where the excess TiO₂ with an amorphous structure is designed to improve the energy storage performance. The dielectric breakdown strength is found to be abruptly improved for the sample with x ≥ 0.65 due to the synergistic contributions from the fine grain size and amorphous phase structure, which greatly decreases the leakage current. Of particular significance is that BMT_x with x = 0.75 exhibits a super high recoverable energy storage density of 126 J cm⁻³ at 5000 kV cm⁻¹, demonstrating the great potential of environmentally friendly BMT_x thin films for energy storage capacitor applications.