Ambipolar diffusion in TiO2

Oriented (100) single crystal of titanium dioxide (rutile) was equilibrated at an ambient oxygen partial pressure p(O-2) 10(-15) to 10(5) Pa, over the temperature range 900-1400 K. After the step change of p(O-2) to a new val ue, the equilibration kinetics was monitored by measuring electrical conduc tivity. Application of the Fick's second law to the kinetic data gave the c hemical (ambipolar) diffusion coefficient for both oxidation and reduction runs. The chemical diffusion coefficient D-chem was found invariant with ox ygen partial pressure. (C) 1999 Elsevier Science B.V. All rights reserved.