Microstructure and dielectric properties of (Nb + In) co-doped rutile TiO2 ceramics

Abstract

The (Nb + In) co-doped TiO2 ceramics recently attracted considerable attention due to their colossal dielectric permittivity (CP) (∼100,000) and low dielectric loss (∼0.05). In this research, the 0.5 mol. % In-only, 0.5 mol. % Nb-only, and 0.5–7 mol. % (Nb + In) co-doped TiO2 ceramics were synthesized by standard conventional solid-state reaction method. Microstructure studies showed that all samples were in pure rutile phase. The Nb and In ions were homogeneously distributed in the grain and grain boundary. Impedance spectroscopy and I-V behavior analysis demonstrated that the ceramics may compose of semiconducting grains and insulating grain boundaries. The high conductivity of grain was associated with the reduction of Ti4+ ions to Ti3+ ions, while the migration of oxygen vacancy may account for the conductivity of grain boundary. The effects of annealing treatment and bias filed on electrical properties were investigated for co-doped TiO2 ceramics, where the electric behaviors of samples were found to be susceptible to the annealing treatment and bias field. The internal-barrier-layer-capacitance mechanism was used to explain the CP phenomenon, the effect of annealing treatment and nonlinear I-V behavior for co-doped rutile TiO2 ceramics. Compared with CaCu3Ti4O12 ceramics, the high activation energy of co-doped rutile TiO2 (3.05 eV for grain boundary) was thought to be responsible for the low dielectric loss.

Giant dielectric permittivity and electronic structure in (Al+Sb)co-doped TiO2 ceramics

“…The e 0 values at 1 kHz and room temperature of the ASTO ceramics sintered at 1300, 1400, and 1500°C are 3714, 1478, and 302, respectively. These values are much lower than that of the (In + Nb) co-doped TiO 2 ceramics [26,35]. This indicates that large defect-dipole clusters containing highly localized electrons may not be generated in the ASTO ceramics.…”

Effect of sintering temperature on structural and dielectric properties of Bi and Li co-substituted barium titanate ceramic

“…This may be due to increasing oxygen vacancies in the material, also the sample sintered at 1300 o C shows a lower frequency relaxation compared to sample sintered at 1250 o C, similar behavior has been reported by Jinglei Li et al in Nb and In Co-doped TiO 2[25] ,this was attributed to the presence of oxygen vacancies at grain boundaries.…”

Structures and dielectric properties of Sr0.9775Sm0.015TiO3 ceramics sintered in N2

“…6(a) shows the ac conductivities of the N 2 -SST0.015 and N 2 -air-SST0.015 ceramics measured at 21 1C and 360 1C. The conductivity increased with the temperature increasing and decreased with the frequency decreasing but never saturated to a constant value at low frequencies, indicating that the main mechanism of the dielectric behaviors of the N 2 -SST0.015 and N 2 -air-SST0.015 ceramics at evaluated temperatures was not the interfacial effects between bulk and electrode [18,19]. As can be seen from Fig.…”