Giant dielectric constant and tunable phase-transition characteristics of ZnF₂/BaF₂-modified BaTiO₃ thick films

High performance capacitors have been investigated to meet higher integration density with optimized charge-storing capability. Here, we introduce nonconventional thick film dielectric compositions based on 95BaTiO₃–xZnF₂–(2−x)BaF₂–3glass (x = 0.5, 1.0, and 1.5) where the relative content of ZnF₂/BaF₂ is critical in controlling dielectric behavior. The thick films were prepared on Cu foils by regular screen-printing and then firing at 950°C in inert atmosphere. As an optimal example, thick film composition modified with 1.0ZnF₂/1.0BaF₂ exhibited a dielectric constant of ~1903 and a dielectric loss of ~0.04 at 1 MHz with dispersive dielectric relaxation behavior, which are far better than any reported corresponding values so far. Particularly, it was very interesting to observe that Curie temperature was tunable from −19 to +34°C, depending on the relative content of fluoride additives only within the 2 mol% range. Dependency of the relative contents of the fluorides is primarily investigated with regard to microstructure and dielectric properties.