Growth of Ultra-Thin TiO<sub>x</sub> and Yb-Ti-O Films on Rh(111)

The growth and structural evolution of ultra-thin TiOx and Yb-Ti-O films on Rh(111) were investigated using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), Auger electron spectroscopy, and photoelectron spectroscopy (PES). After Ti deposition and subsequent oxidation–vacuum annealing cycles, well-ordered ultra-thin TiOx films exhibited a TiOx-(9 × 9) superstructure commensurate with the Rh(111)-(10 × 10) lattice. Upon Yb deposition, no LEED patterns were observed, and the STM images revealed an uneven surface morphology, indicating the formation of disordered Yb species. After the simultaneous deposition of Ti and Yb atoms, followed by oxidation and reduction steps, an ordered ultra-thin Yb-Ti-O film was formed, exhibiting a Yb-Ti-O-(3 × 3) superstructure commensurate with the Rh(111)-(4 × 4) lattice, together with a fundamental Yb-Ti-O-(1 × 1) lattice. The surface phase diagram summarizes the coverage-dependent evolution from binary TiOx and YbOx to a ternary Yb-Ti-O ordering phase. These results provide an experimentally verified framework for understanding how rare-earth incorporation modifies ultrathin Ti-O networks on metal surfaces and may guide future exploration of more complex oxide tiling in rare-earth oxide quasicrystals.