Electronic and ionic conductivity of TiO 2 single crystal within the n–p transition range

Abstract

The electrical conductivity of TiO 2 single crystal (rutile) was determined within the n–p transition regime in the temperature range 985–1387 K and p(O 2) 1–10 5 Pa. The determined values of the p(O 2) exponent differ from those predicted by defect disorder models (in both n- and p-type regimes), which were derived assuming validity of ionic charge compensation. This difference allows the evaluation of the ionic conductivity. The ionic component thus determined within the n–p transition regime exhibits an activation energy of E a=158 kJ mol −1. It was found that the ionic transfer number for undoped TiO 2 at the n–p transition is approximately 0.5. The electronic conductivity component was used to determine the width of the forbidden gap of TiO 2 (E g=2.86 eV).