Origin of colossal dielectric response in (In + Nb) co-doped TiO2 rutile ceramics: a potential electrothermal material

Abstract

(In + Nb) co-doped TiO2 (TINO) rutile is an emerging material with a colossal dielectric permittivity (CP) and a low dielectric loss over wide temperature and frequency ranges. The electrical inhomogeneous nature of TINO ceramics is demonstrated by direct local current probing with high-resolution conductive atomic force microscopy (cAFM). The CP response in TINO is found to originate from the electron-pinned defect dipole induced conductive cluster effect and the electrode effect. Two types of dielectric relaxations are simultaneously observed due to these two effects. With the given synthesis condition, we found TINO shows a highly leaky feature that impairs its application as a dielectric material. However, the fast-temperature-rising phenomenon found in this work may open a new door for TINO to be applied as a potential electrothermal material with high efficiency, oxidation-proof, high temperature stability, and energy saving.

Microstructure, colossal permittivity, and humidity sensitivity of (Na, Nb) co‐doped rutile TiO2 ceramics

“…The Maxwell‐Wagner relaxation around RT has been widely reported in (A, B) co‐doped rutile TiO 2 ceramics. A variety of mechanisms, such as electrode effect, internal barrier layer capacitor effect, and grain boundary response, were proposed to account for this relaxation. However, the Maxwell‐Wagner relaxation in present sample as aforementioned would be associated with humidity response.…”

Abnormal dielectric relaxations and giant permittivity in SrTiO3 ceramic prepared by plasma activated sintering

“…In 2013, Liu's Group 10 explored a new material system, (In + Nb) co‐doped TiO 2 ceramic, which simultaneously achieved giant permittivity and low dielectric loss. The excellent dielectric behavior was ascribed to electron‐pinned defect‐dipoles, and this theory was applied in other co‐doped TiO 2 ‐based ceramics as well 11–13 . However, this theory had limitations in explaining the inhomogeneous resistance in materials.…”

“…The excellent dielectric behavior was ascribed to electron-pinned defect-dipoles, and this theory was applied in other co-doped TiO 2 -based ceramics as well. [11][12][13] However, this theory had limitations in explaining the inhomogeneous resistance in materials. Alternative polarization mechanisms, such as surface barrier layer capacitance effect, 14,15 internal barrier layer capacitance (IBLC) effect, [16][17][18] and hopping of charge carriers 19,20 were put forward.…”

Low‐temperature Maxwell‐Wagner relaxation in (Na + Nb) co‐doped rutile TiO2 colossal permittivity ceramics

“…With the discovery of superior colossal permittivity (CP) behavior in (Nb + In) co‐doped TiO 2 (NITO), a current burst of research activities on dual doping of TiO 2 ceramics have been stimulated. After a wealth of experimental investigations, several mechanisms, such as electron‐pinned defect‐dipole, surface barrier layer capacitor model, internal barrier layer capacitor model, surface layer effect, electron polarization, and non‐Ohmic sample‐electrode contact, had been proposed to account for this behavior. Hence, there is an ongoing debate regarding the exact origin for the CP behavior in the co‐doped TiO 2 system.…”