Diffusion Kinetics of Indium in TiO₂ (Rutile)

Abstract

This work determines the self‐diffusion coefficients of indium in TiO2 single crystal (rutile). Diffusion concentration profiles were imposed by deposition of a thin surface layer of InCl3 on the TiO2 single crystal and subsequent annealing in the temperature range 1073–1573 K. The diffusion‐induced concentration profiles of indium as a function of depth were determined using secondary ion mass spectrometry (SIMS). These diffusion profiles were used to calculate the self‐diffusion coefficients of indium in the polycrystalline In2TiO5 surface layer and the TiO2 single crystal. The temperature dependence of the respective diffusion coefficients, in the range 1073–1573 K, can be expressed by the following formulas: DIn−In2TiO5=1.9×10−13exp(−1420.35emkJ/molRT)[m2s−1] and DIn−TiO2=7.4×10−4exp(−3160.35emkJ/molRT)[m2s−1] The obtained activation energy for bulk diffusion of indium in rutile (316 kJ/mol) is similar to that of zirconium in rutile (325 kJ/mol). The determined diffusion data can be used in selection of optimal processing conditions for TiO2–In2O3 solid solutions.

Origin of the abnormal diffusion of transition metal atoms in rutile

“…1(b). For Ti, the migration barrier for diffusion perpendicular to c axis is 0.60 eV, slightly lower than that along c direction (0.61 eV), in good agreement with the experimental data [35] and other calculations [15]. The migration of the V atom from the stable interstitial site to the substitutional transition site has a high energy barrier of 1.42 eV, while the reverse migration (trapping) has a barrier of 0.94 eV.…”

Niobium Segregation in Niobium-Doped Titanium Dioxide (Rutile)

“…Therefore, only the part of the spectra on the right side of the vertical line is considered as meaningful for the oxide lattice. 45 Consequently, the depth is referred to as the vertical line that is marked as d = 0. The depth profiles shown in Figure 8 indicate that (i) the highest intensity ratio of Nb/TiO at the surface (d = 0) is observed for the specimen annealed at p(O 2 ) = 75 kPa.…”

Dual Mechanism of Indium Incorporation into TiO2 (Rutile)

“…13 The conditions of the final annealing time, which aimed at homogeneous distribution of indium, were determined based on the diffusion data of indium in TiO 2 . 34 The electrical conductivity and thermoelectric power were determined simultaneously at 1273 K using the High-Temperature Seebeck Probe. 23 The oxygen activity in the gas phase was imposed using the argon−oxygen mixture and the argon−hydrogen mixture in order to achieve oxidizing and strongly reducing environment, respectively.…”