High-Dielectric Constant Inorganic–Organic Hybrid Materials Prepared with Sol–Gel-Derived Crystalline BaTiO₃

The preparation of ceramic/polymer composites (BaTiO₃–polymer in particular) has received much current interest for various electronic applications, because of the possibility of combining the effect of the processability of the organic components with that of the desired electrical properties of the ceramics. The synthesis of polyimide-based inorganic–organic hybrid thin films containing crystalline BaTiO₃ nanoparticles and their dielectric properties are discussed. The precursor for the polyimide was prepared from benzophenone-3,3',4,4'-tetracarboxylic dianhydride (BTDA) and 4,4'-diamino-3,3'-dimethyl diphenyl methane (DADMDPM) and used as an organic matrix for a ceramic/polymer hybrid and that of the crystalline BaTiO₃ nanoparticles was prepared by the wet-chemical decomposition of the [Ti(acac)₃]⁺ complex with Ba(OH)₂. The BaTiO₃, prepared by the decomposition of the Ti-acac complex showed good crystallinity (average particle size = 90 nm) with better dispersibility in an organic medium (NMP). Crack-free thin films of 3.5–4.5 µm thickness were obtained by a single spin coating operation after curing the air-dried films at 150 °C. The polyimide/BaTiO₃ hybrids exhibited a wide range of relative permittivity values (ε= 3.81–31.57) at room temperature.