LEED and AES study of structural and chemisorptive properties of Zr overlayers on the Pt(100) crystal face

Abstract

Zirconium overlayers were deposited onto a Pt(100) surface by electron beam evaporation in UHV, and the composition and structure of the surface was determined by AES and LEED. The overlayers were highly reactive towards oxygen, carbon monoxide, and hydrocarbons, forming oxide or carbide overlayers. Several metastable ordered structures were observed by LEED when oxidized overlayers were thermally annealed in UHV. Protracted annealing at >900 K results in reduction and dissolution of the oxidized overlayer with complete disappearance of zirconium from the surface. Oxygen dosing of annealed surfaces at 25 °C caused resegregation of zirconium to the surface, and the formation of an ordered PtZrxOy surface phase which may be a zirconia analog to the yttria ternary oxide PtYO3.5. This phase was stable in oxygen at 25–300 °C, but oxygen dosing at above 300 °C resulted in precipitation of ZrO2 islands on top of the Pt(100)-(1×1) substrate.