Temperature stable high energy density capacitors using complex perovskite thin films

Chemical solution derived thin film synthesis and dielectric characterizations of (1-x)BaTiO₃-xBi(Mg,Ti)O₃ complex perovskiteswith compositions x<;0.15 have been explored for temperature stable high energy density capacitor applications. Solution chemistry has been optimized to synthesize and stabilize the precursor solution. Solution derived (1-x)BaTiO₃-xBi(Mg,Ti)O₃ thin film samples were fabricated in thickness ~500 nm by spinning and subsequent crystallization. These thin films showed nearly linear polarization response with high relative dielectric permittivity exceeds 900, that is beneficial to high capacitance density and energy density of the capacitors. Average dielectric breakdown strengths of the dense films were as high as 2.17 MV/cm. The BaTiO₃-Bi(Mg,Ti)O₃ samples showed very low leakage current densities in magnitudes of 10-8 A/cm² order even at high temperatures up to 200°C. Based on the structural stability at high temperatures of the pseudocubic perovskite, the high dielectric permittivity and the typical P-E behaviors of the BaTiO₃-Bi(Mg,Ti)O₃ thin films were also maintained at such high temperatures. Resulting energy density of the 500 nm thick 0.88BaTiO₃-0.12Bi(Mg,Ti)O₃ thin film was as high as 37 J/cm³ at 1.9 MV/cm. The enormous energy density and high temperature stability of the BaTiO₃-Bi(Mg,Ti)O₃ complex perovskite promise its applications in high temperature pulse power capacitors.