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 perovskites with 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 in thicknesses ranging from 250 to 500 nm were fabricated by repeated spinning and subsequent crystallization processes. These thin films showed nearly linear polarization response with high relative dielectric permittivity exceeding 900, which is beneficial for high-capacitance-density and high-energy-density capacitors. Average dielectric breakdown strengths of the dense films were as high as 2.08 MV/cm. The BaTiO₃-Bi(Mg,Ti)O3 samples showed very low leakage current densities of the order of 10-8 A/cm2 even at temperatures of 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 high energy density and excellent temperature stability of the BaTiO₃-Bi(Mg,Ti)O₃ complex perovskite show promise for use in high-temperature pulse power capacitor applications.