Mössbauer Study of the Chemical Behavior of Tin Dopant Atoms on the Surface of Cr2O3Microcrystals: Transformations Induced by Exposure to Ambient Atmosphere after Contact with H2S
✍ Scribed by M. Danot; M.I. Afanasov; A.A. Ryabchikov; S. Maingaud; P.B. Fabritchnyi; J. Rouxel
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 299 KB
- Volume
- 132
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Appearance of a particular tin dopant ion distribution with respect to the surface of Cr 2 O 3 substrate after H 2 S adsorption and subsequent exposure of the sample to air at room temperature has been revealed using 119 Sn probe Mo¨ssbauer spectroscopy. The results obtained show that drastic changes occur in the chemical composition of the first cationic layer of the substrate during H 2 S adsorption. The subsequent contact with air results in oxidation of both Sn 2؉ dopant ions and adsorbed H 2 S molecules. The Sn 4؉ ions formed in the oversurface shell consisting of H 2 S oxidation products appear to be magnetically isolated to a large extent from the substrate surface. However, after annealing under hydrogen flow, instead of forming -Sn clusters, even the most isolated Sn 4؉ ions are shown to recover their initial divalent state and to return surface sites similar to those occupied by Sn 2؉ ions prior to H 2 S exposure.