CHARACTERIZATION OF CA IMPURITY SEGREGATION ON THE TIO2(110) SURFACE

TiO2(110) single crystals with trace amounts of Ca impurities were inv estigated by ISS, XPS, LEED, and STM. After initial cleaning and with increasing annealing temperature, ISS and XPS clearly show the segrega tion of Ca to the surface of fresh TiO2(110) crystals. As revealed by LEED and STM, a [GRAPHICS] structure is formed as an overlayer, with r ow-like features along the substrate [001] direction. In line with the Ca 2p(3/2) peak position of 347.4 eV, we propose the formation of a C aTiO3-like compound, oriented with its (110) face parallel to the subs trate. (C) 1998 Elsevier Science B.V. All rights reserved.