Giant dielectric behavior from multiple effects in (Na+Ta) co-doped TiO2 ceramics

Materials with colossal permittivity (CP) have been extensively investigated for their promising applications in energy storage devices. In this work, the composition, microstructure and dielectric properties of (Na 0.25 Ta 0.75 ) x Ti 1–x O 2 (x = 0–0.04) ceramics were systematically investigated. Co-doped TiO 2 ceramics demonstrated giant dielectric constants. The optimized dielectric properties were achieved in (Na 0.25 Ta 0.75 ) 0.02 Ti 0.98 O 2 with high dielectric constant (7.32 × 10 4 ) and low loss (0.034) at 1 kHz. The origin of CP was explored by dielectric, complex impedance spectroscopy and X-ray photoelectron spectroscopy measurements. The giant dielectric constant primarily stems from the electronic pinning defect dipole effect and the internal barrier layer capacitance effect. This finding might shed light on the design of high-performance giant dielectric materials.