REM observations of oxygen-annealed rutile (001) surfaces

Rutile (single crystal TiO2) is widely used in electrochemistry, photochemical energy conversion and photocatalytic reactions of gases as a catalytic material. It is important to characterize the surface properties of rutile in order to understand its catalytic behavior. The rutile (001) surface is extremely unstable, forming facets on annealing as revealed by the LEED results. In this paper we report some preliminary results on the investigation of oxygen annealed rutile (001) surface, obtained by reflection high energy electron diffraction (RHEED) and reflection electron microscopy (REM) techniques.The crystal was cut into strips, finely polished, cleaned and chemically etched in NaOH and H2SO4 before annealing. The samples were annealed in pure oxygen at 1473 K for 36 h. The purposes of annealing the samples in pure oxygen are to preserve surface stoichiometry and to prevent surface reactions with elements other than oxygen during the annealing process. The RHEED and REM observations were performed in a Philips 400T microscope operated at 120 kV.