0000000000186030
AUTHOR
L. C. Dufour
showing 4 related works from this author
Etude cinétique de la réduction dans l'hydrogène d'oxydes spinelles de cobalt faiblement substitués par le chrome
1991
La reduction par l'hydrogene a 250 °C des oxydes spinelles Co3-x Crx O4 (0 ≤ x ≤ 0,5) a ete etudiee dans des conditions de regime chimique en fonction du taux de subtitution en chrome, x, d'une part, et de variations du protocole experimental d'autre part. La phase CoO pure ou substituee par Cr est formee intermediairement. Les cinetiques respectives de la reduction du spinelle en CoO et la reduction de CoO en metal sont modifiees par des changements mineurs du protocole experimental. On observe un changement graduel de regime cinetique du type lineaire au type parabolique avec l'augmentation du taux de chrome: le taux limite suppose de solubilite du chrome dans CoO separe deux domaines dif…
Temptative Modeling of Surface Reactivity with Oxidizing-Reducing Mixtures on Rutile TiO2-δ
1989
Rutile bears some unique features in regard to oxygen transfer with the outer atmosphere, at high temperatures. It possesses very high chemical diffusivity. This diffusivity becomes apparent while performing reequilibration experiments in a final atmosphere of pure oxygen. Conversely, the oxidizing-reducing reaction with CO/CO2 mixtures at the rutile surface is always a slow process.
The growth of oxide platelets on nickel in pure oxygen. II. Surface analyses and growth mechanism
1993
The structural properties of NiO platelets emerging from a primary oxide layer by oxidation of pretreated nickels in pure oxygen between 650 and 800° C have been investigated in relation with the initial metallic layers and the primary oxide. Surface composition and segregation of impurities were also studied by X-ray photoelectron spectroscopy and Auger electron spectroscopy. Textural properties and structural orientation of both the primary oxide layer and the platelets were analyzed by X-ray diffraction and transmission electron microscopy. Platelets grew along {111} planes, leading to elliptical or semicircular bicrystals. The driving force for the present type of growth originates from…
Defects and Reactivity at Oxide Surfaces: Experimental Aspects of the Interaction of Hydrogen, Co And Co2 with the Nio{001} Surface
1989
This paper summarizes some previous or more recent experimental results on chemical interaction, at moderate temperatures, of H, H2, CO and CO2 with the surfaces of nickel oxide, mainly the NiO {001} surface. These results are in a general agreement with theoretical predictions. Nearly perfect surfaces of maximal valency oxides cannot react with molecules. Dissociation of molecules is often required for chemisorption. Conversely, chemical reaction is usually observed either when molecules are predissociated or the surface has defects with an energy level high enough to enable both dissociation and chemisorption. On a nearly perfect, “in situ” cleaved, NiO {001} surface, partially atomized h…