Synthesis of calcium copper titanate (CaCu₃Ti₄O₁₂) nanowires with insulating SiO₂ barrier for low loss high dielectric constant nanocomposites

The discovery of a giant dielectric constant of >10⁵ in calcium copper titanate (CCTO) has generated significant interest for application in electronic devices. Over the past decade, many methods have been developed to synthesize CCTO particles in an effort to capitalize upon the outstanding dielectric properties. Polymer film capacitors are one application where CCTO could greatly increase the typically low dielectric constant of the polymer. Recent work has shown that the aspect ratio of the dispersed filler can greatly affect the dielectric constant of the polymer with high aspect ratio nanowires (NWs) producing greater dielectric constant and energy density than spherical particles. While CCTO NWs hold great potential to improve the properties of nanocomposite capacitors, no method currently exists for their preparation and their integration is challenged by the barrier layer capacitance which leads to high dielectric loss. Here, a novel two-step hydrothermal reaction is developed for the large-scale synthesis of CCTO NWs and an insulating barrier layer is applied to greatly reduce the loss while preserving the high dielectric constant.