Colossal permittivity of Sb and Ga co-doped rutile TiO2 ceramics

Material with colossal permittivity (CP) is important for the miniaturization of electronic devices and fabrication of high-density energy storage devices. However, the unbalanced developments of dielectric constant, dielectric loss and stability preclude its practical applications. In this work, we report that Sb + Ga co-doped TiO2 (SGTO) ceramics exhibit colossal permittivity and low dielectric loss. Especially, a high dielectric permittivity of 3.5 x 10(4) and a low dielectric loss of 0.06 at 1 kHz are obtained in the optimum composition with x = 0.02. The dielectric property shows high stability in wide temperature (25-130 degrees C) and frequency (20-10(6) Hz) range. XPS, complex impedance spectroscopy, I-V curve and frequency dependent dielectric constant under DC bias results indicate that electron-pinned defect-dipoles (EPDD) model, internal barrier layer capacitance (IBLC) effect and electrode effect all contribute to the observed colossal permittivity behavior in (Sb0.5Ga0.5),Ti1-xO2 ceramics.