XPS Evidence for the Incongruent Surface Oxidation of Minerals in the Pd-Te-BiSystem

✍ Scribed by Elvy, S. B.; Williams, P. A.; Buckley, A. N.

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 650 KB
• Volume: 24
• Category: Article
• ISSN: 0142-2421
• DOI: 10.1002/(sici)1096-9918(19960916)24:9<641::aid-sia150>3.0.co;2-w

✦ Synopsis

Selected members of the Pd-T&Bi system (PdTe, PdTeBi and PdBi) have heen synthesized from their constituent elements, their structure and phase integrity confirmed by x-ray diffraction and optical microscopy and their initial oxidation in air under ambient conditions investigated by means of XPS. Prior to air exposure, the Pd coreelectron binding energies were 0.6-1.0 eV higher than the corresponding values for the pure metal, while the core-level shifts for the alloying elements were very small. In each case, oxidation was quite rapid, but the palladium did not appear to be directly involved in the initial reaction; no change in the Pd 3d spectrum other than in its intensity was observed, notwithstanding the formation of significant amounts of tellurium oxide and/or bismuth oxide. The electron spectra were consistent with an incongruent oxidation reaction leading to the formation of a layer of tellurium and/or bismuth oxide covering a palladium-enriched substrate.