Effect of TiO2 on the Sintering and the Electrical Conductivity of Cr2O3

Abstract

The effect of TiO2 addition on the sintering behavior and the electrical conductivity of Cr2O3 was studied at 1473 K at various oxygen pressures, 105 > Po2 > 10−10 Pa. TiO2 addition of more than 1 wt% drastically enhanced the sintering of Cr2O3 in the oxygen pressure range 10−3 Pa > Po2 because of the marked increase in the concentration of Vmcr and Vö by introduction of tetravalent titanium ions into Cr2O3. The sintering rate decreased slightly with decreasing Po2 below 10−5 Pa, where the concentration of tetravalent titanium ions is low. The Po2 dependence of the electrical conductivity of Cr2O3 was also drastically altered by TiO2 addition. Undoped Cr2O3 had a p‐type conductivity in the whole Po2 range investigated, while Cr2O3—1% TiO2 passed through a minimum and became an n‐type conductor in the whole Po2 range because of the increase in the concentration of electrons [Ticr] = [e′]. The Po2 dependence and the TiO2 dependence on the sintering rate of the Cr2O3—xTiO2 may be completely explained by the alteration in defect structure.