PNNL

Abstract

Since oxygen atom vacancies play a central role in the behavior of oxide materials, determining their properties is widely pursued both experimentally and theoretically. As a function of temperature between 340 and 420 K, we report here the first measurements and calculations of the intrinsic mobility of bridge-bonded oxygen atom vacancies on a TiO2(110) rutile surface. Under conditions where interference by adsorbates was negligible, isothermal atomically-resolved scanning tunneling microscope images that track individual vacancies in real time show that, vacancies migrate exclusively along bridging oxygen atom rows. The hopping rate increases exponentially with increasing temperature with experimental activation energy of 1.15 eV. Density functional theory calculations are in very good agreement giving an energy barrier for hopping of 1.034 eV. Both theory and experiment, indicate a short-range repulsive interaction between vacancies on a given bridge-bonded oxygen atom row.