Colossal permittivity and impedance analysis of niobium and aluminum co-doped TiO₂ ceramics

Abstract

Niobium and aluminum co-doped TiO2 ceramics, i.e., (Nb0.5Al0.5)xTi1−xO2 (x = 0, 0.01, 0.05, 0.1, 0.15, abbreviated as NAT100x) were synthesized via a solid-state reaction route.

Structural Phase Transition and Metallization of Nanocrystalline Rutile Investigated by High-Pressure Raman Spectroscopy and Electrical Conductivity

“…An anomalously strong and broad peak at 242 cm −1 is a multi-phonon peak caused by the second-order Raman scattering experiment in rutile structure. All of these observed Raman characteristic peaks are in good agreement with previous studies in ambient conditions [21,22]. At the pressure range of 0-12.3 GPa, all of the Raman peaks for rutile phase shifted toward higher frequencies with increasing pressure, except for the B 1g soft mode.…”

Surface barrier layer effect in (In + Nb) co‐doped TiO2 ceramics: An alternative route to design low dielectric loss

“…According to the EPDD model, the giant dielectric response was resulted from the formation of large defect dipole clusters in the grain interiors, in which free electrons were confined in the special local structure . For the IBLC model, the giant dielectric response in INTO and other co‐doped TiO 2 ceramics was thought to be caused by the interfacial polarization at insulating grain boundaries …”

“…Temperature independence of ε′ over the range of 80‐450 K was reported for this material. This discovery stimulated research in the field of giant dielectric materials based on TiO 2 for application in high‐performance capacitors due to its abundance and low toxicity . According to the nominal composition of (In 0.5 Nb 0.5 ) x Ti 1− x O 2 , the complex stoichiometry of (In x 3+ Nb x 5+ Ti x 3+ )Ti 1−3 x 4+ O 2− x /2 produced defect clusters, giving rise to very high ε′ values.…”

Origin(s) of the apparent colossal permittivity in (In1/2Nb1/2)xTi1−xO2: clarification on the strongly induced Maxwell–Wagner polarization relaxation by DC bias

“…[10][11][12] This means that there are several factors that have signicant inuences on the dielectric properties of TiO 2 -based materials. Even though the electronpinned defect-dipole model has been a reasonably novel model for describing the origin of the high-performance dielectric properties of IN-T ceramics, Maxwell-Wagner polarization at the grain boundaries (GB) (i.e., the internal barrier layer capacitor effect, IBLC) has also been proposed as their exact origin, 11,[13][14][15][16][17] which creates signicant confusion. Thus, the origin of the high performance dielectric properties of TiO 2based ceramics must be claried.…”