Photoemission study of Ce/Ta(110) and Ce/W(110) interfaces and the catalytic oxidation effect

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:7183109

Gu, Chun

A weak Ce/Ta interface reaction is illustrated by the reduced Ta 4f surface core-level shift (SCS) upon Ce adsorption. No Ce/Ta interdiffusion was found. The Ce layer may greatly enhance the oxidation of Ta(110). Oxidation of Ce/Ta(110) at 300 K yields one monolayer (ML) of Ta suboxide ([approximately]TaO), followed by the rapid formation of Ta[sub 2]O[sub 5]. Ce/W(110) adsorption patterns were determined by low-energy electron diffraction. For [Theta] [le] 0.5 ML, the adsorption structure is characterized by one-dimensional commensuration along the [110] direction. It changes abruptly to a hexagonal pattern after 0.5 ML. The interatomic spacing shrinks continuously from 9% larger than that for [gamma]-Ce to 3% smaller than that for [alpha]-Ce. Correspondingly, the Ce 4f photoelectron spectrum evolves to resemble that of [alpha]-Ce. W 4f core levels are also correlated to the adsorption structure. The surface monoxide formation found on Ce/Ta(110) and Ce/W(110) is not an inherently necessary step in the catalytic oxidation, but rather an interface product on the most densely-packed bcc (110) surfaces.

• Research Organization: Iowa State Univ. of Science and Technology, Ames, IA (United States)
• OSTI ID: 7183109
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ADSORPTION
CATALYTIC EFFECTS
CERIUM
CHEMICAL REACTIONS
ELEMENTS
INTERFACES
KINETICS
METALS
OXIDATION
RARE EARTHS
REACTION KINETICS
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
TANTALUM
TRANSITION ELEMENTS
TUNGSTEN