A LEEM/mu-LEED investigation of phase transformations in TiOx/Pt(111) ultrathin films

作者：Agnoli Stefano; Mentes T Onur; Nino Miguel A; Locatelli Andrea; Granozzi Gaetano^*

来源：Physical Chemistry Chemical Physics, 2009, 11(19): 3727-3732.

DOI：10.1039/b821339a

A combined use of low energy electron microscopy (LEEM) and microprobe LEED (m-LEED) allows the in-situ observation of dynamical processes at the TiOx/Pt(111) interface. The transformations between different surface-stabilized phases are investigated in the case of room temperature TiOx reactive deposition with subsequent post-annealing. For a coverage of 0.6 MLeq, UHV annealing to 400 degrees C leads to the formation of the zigzag-like z-TiO1.33 layer. At higher temperatures a rotated z-TiO1.33 phase is observed, its lateral distribution being strongly influenced by surface morphology. Concurrently, the z-TiO1.33 layer partially transforms into a kagome-like TiO1.5 structure. The resulting oxygen enrichment of the interface is interpreted by invoking Ti interdiffusion into the substrate. At a coverage of 0.45 MLeq, UHV annealing at 500 degrees C transforms the z-TiO1.33 layer into a different zigzag-like z'-TiO1.25 layer. Post-annealing in oxygen of the reduced phases or direct reactive deposition at high temperature both produce the rect-TiO2 stoichiometric phase, showing characteristic needle-like domains aligned according to the rect-TiO2 unit cell orientation.

• 出版日期2009