H. Norenberg et Jh. Harding, Ordered structures of calcium oxide on TiO2(110) studied by STM and atomistic simulation, PHYS REV B, 59(15), 1999, pp. 9842-9845
A well-ordered surface layer of Ca on TiO2(110) has been prepared by forcin
g Ca impurities from the bulk to segregate to the surface during annealing,
The surface was studied by scanning tunneling microscopy (STM), Auger elec
tron spectroscopy, low-energy electron diffraction, reflection high-energy
electron diffraction, and atomistic simulation. Calcium forms a p(3 X 1) re
construction. The reconstructed areas extend well beyond the scanning range
of the STM. Calculations have shown that calcium in TiO2 will segregate to
the surface to occupy the positions of the fivefold coordinated Ti ions. O
rdering is energetically favorable with the p(3X1) reconstruction lowest in
energy. Calcium is sitting on top of the surface. It is concluded that the
STM contrast is strongly influenced by geometric effects. [S0163-1829(99)1
2515-3].