Growth of Ba-O ultrathin films on Pt(111) followed by Ti incorporation to prepare oxide crystalline approximants and quasicrystals

In this study, three different precursor Ba-O films on Pt(1 1 1) are characterized and the oxide crystalline approximant (OCA) and oxide quasicrystal (OQC) films are prepared by annealing after Ti deposition on the films. The prepared Ba-O ultra-thin films are BaO(1 0 0)-(root 2x root 2)R3 degrees:Pt(1 1 1), Ba-O:Pt(1 1 1)-(2 x 2) and Ba-O:Pt(1 1 1)-(root 13x root 13)R13.9 degrees, as determined using scanning tunneling microscopy, low-energy electron diffraction, and X-ray photoelectron spectroscopy. The phase transformation from an OCA film to an OQC film likely follows the mechanism where Ti is reduced and its surface atomic density decreased, while Ba is oxidized. The schematic structural models of the OCA film as Ba4Ti4O10 and the OQC film as Ba12Ti5O12, where the Ba atoms form a cluster tiling, are proposed.

Automated summary

In this study, three different precursor Ba-O films on Pt(1 1 1) were characterized and oxide crystalline approximant (OCA) and oxide quasicrystal (OQC) films were prepared via Ti deposition and annealing. Analysis revealed phase transformation likely follows Ti reduction and Ba oxidation, leading to a change in surface atomic density. Structural models proposed for the OCA and OQC films involve cluster tiling of Ba atoms.