Bismuth oxide modified europium and niobium co-doped titanium dioxide ceramics: Colossal permittivity and low dielectric loss design

Colossal permittivity (CP) materials have many important applications in electronics but their development is generally hindered due to the difficulty in achieving a relatively low dielectric loss. In this work, based on the electron-pinned defect-dipole and internal barrier layer capacitance (IBLC) theory, we designed to add Bi₂O₃ to (Eu_0.5Nb_0.5)_0.01Ti_0.9O₂ (ENTO) ceramics to obtain high performance CP materials. The dielectric loss can be reduced down to 0.017 at 1 kHz and room temperature, while the permittivity is kept at a relatively high value (2.7 × 10⁴). At the same time, the temperature and frequency stability can also be improved. More importantly, the mechanism of decreasing dielectric loss is studied. It is finding that the decrease of dielectric loss is closely associated with the enhanced localized behavior of conduction process at grain boundary. The addition of Bi₂O₃ can increase the grain boundary resistance and grain-boundary activation energy of the ceramics, which make the conductive behavior of the grain boundaries more difficult, resulting in decreasing the dielectric loss and improve the temperature stability of the ceramics.