Structure and stability of the anatase TiO2 (101) and (001) surfaces

Well-defined (101) and (001) surfaces of anatase TiO2 were studied for the first time by secondary-electron imaging and low-energy electron diffractio n. Initially, both surfaces show a crystalline structure corresponding to t he bulk anatase phase, buried under an atomically thin contamination layer. After mild sputtering with 500 eV Ne+ ions, we have observed a surface pha se transition from tetragonal anatase to face-centered cubic titanium monox ide TiO. Subsequent annealing at 900 K restores the (1 x 1) anatase structu re at the (101) surface. On the (001) surface, however, a (1 x 4) reconstru ction appears. The unreconstructed structure can be recovered by exposing t he surface to oxygen. These observations demonstrate the stability of the a natase surfaces and illustrate the feasibility of preparing and investigati ng clean surfaces of this technological important form of TiO2. (C) 2000 El sevier Science B.V. All rights reserved.