Effects of Eu3+/Ta5+ nonstoichiometric ratio on dielectric properties of (EuxTa1-x)0.08Ti0.92O2 ceramics with colossal permittivity: Experiments and first-principle calculations

Abstract To in-depth understand the effects of donor and acceptor elements on the colossal permittivity (CP) properties, the Eu3+ and Ta5+ ions are selected to synthesize rutile TiO2-based ceramics. The relationship of co-doping composition, secondary phase, crystal structure and dielectric properties is systematically investigated using experiments and the first-principle calculations. Notably, the introduction of heterogeneous ions entering the crystal matrix induces the structural deformation and oxygen vacancies, which acts an important role in regulating the functional performance (dielectric constant, loss and temperature stability). Meanwhile, the CP behavior of co-doped ceramic is attributed to the interface barrier layer capacitor (IBLC) effect constituted by the semiconductive grains and insulated grain boundaries, and secondary phase with a spot of Ta element influences the grain boundary activation energy and dielectric performance.