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

Pure perovskite Bi(Mg 0.5 Ti x )O 3 (abbreviated as BMT x ) thin films are successfully fabricated on Pt/Ti/SiO 2 /Si substrates by a sol-gel method, where the excess TiO 2 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. Amorphous engineering can effectively tailor energy storage performances of dielectrics due to the improvement of dielectric breakdown.