Colossal permittivity of (Gd plus Nb) co-doped TiO2 ceramics induced by interface effects and defect cluster

Material with high dielectric constant plays an important role in energy storage elements. (Gd + Nb) co-doped TiO2 (GNTO) ceramics with giant dielectric permittivity (>10(4)), low dielectric loss, good temperature and frequency stability in broad range of 30-150 degrees C and 10(2)-10(6) Hz have been systematically characterized. Especially, a low dielectric loss of 0.027 and a giant dielectric permittivity of 5.63 x 10(4) at 1 kHz are attained for the composition with x = 0.01. Results of complex impedance spectroscopy, I-V curve and frequency dependent dielectric constant under DC bias indicate that internal barrier layer capacitance (IBLC) effect, electrode effect and electron-pinned defect-dipole (EPDD) effect contribute to the colossal permittivity (CP) property simultaneously.