Stability of giant dielectric properties in co‐doped rutile TiO2 ceramics under temperature and humidity

This research investigated the influence of temperature and humidity on the giant dielectric (GD) properties of 1% indium tin oxide and 1% Ta2O5 co‐doped TiO2 ceramics sintered at different temperatures. A single phase of rutile TiO2 was obtained in all sintered samples. The mean grain size increased with higher sintering temperatures, resulting in ceramics with a relative density exceeding 98%. A uniform dispersion of dopants and major elements was achieved. Remarkably, the dielectric constant increased significantly from 2 × 103 to 3.7 × 104 with a rising sintering temperature, primarily due to the enlarged grain size. Concurrently, the authors observed low loss tangents, ranging from tanδ≈0.016 to 0.024 at 1 kHz. Slight variations in the dielectric constant were observed with temperature from room temperature up to 210°C, while maintaining remarkably low tanδ. The GD properties were attributed to space charge polarisation at internal interfaces and defect dipoles. Further research explored the impact of environmental conditions on dielectric properties. Remarkably, the ceramics exhibited minimal capacitance variations of less than 10% within the relative humidity range of 30%–95% and temperatures from 15 to 85°C, indicating excellent dielectric stability.