High performance and colossal permittivity of (Nb plus La) co-doped rutile TiO2 ceramics induced by composition regulation

Donor-acceptor co-doped rutile TiO2 ceramics with colossal permittivity have been paid more attention recent years. However, the application of the ceramics in high-energy-density storage devices was limited by the low breakdown strength of co-doped TiO2 colossal permittivity ceramics, therefore the dielectric properties of NbxLa0.004Ti0996-xO2 (x:0.004=1:1, 1.02:1, 1.04:1, 1.06:1, 1.08:1) ceramics were investigated. Colossal permittivity with low dielectric loss and high dielectric strength was found in NbxLa0.004Ti0.996-xO2 (x:0.004=1.04:1) ceramics. The enhancement dielectric properties with larger Nb5+ doping concentration in co-doped ceramics provide the colossal permittivity mechanism in (Nb+La) co-doped TiO2 ceramics could be attribute to the electron-pinned defect-dipole effect. Furthermore, finding the proper donor concentration is a feasible way to enhance the dielectric strength to satisfy the condition for application in high-energy-density storage devices.