Surface composition of some selected Group VIII/gold and Group VIII/tin alloys

P. Biloen, R. Bouwman, R.A. Santen, van, H.H. Brongersma

Research output: Contribution to journalArticleAcademicpeer-review

34 Citations (Scopus)
44 Downloads (Pure)


We have determined the surface composition of three different solid solu tions (5 at. % Ni-Au, 4 at. % Pd-Au and 14 at. % Pt-Au) and two stoichiometric compounds (Ni3Sn and Pt3Sn), all of them selected because of their significance in current catalytic work on group VIII/"inert metal" alloys. Low-energy ion scattering (LEIS), Auger spectroscopy (AES) and selective CO chemisorption, applied to Pt3Sn and Ni3Sn, yield consistent results. For both alioys the three techniques indicate surface enrichment in tin, which is more pronounced for Ni3Sn. Averaged over the three different techniques, the surface compositions work out at PtO.48 SnO.S2 and Nio.21 SnO.79 respectively. When comparing these results with theoretical predictions we notice that the restricted bond-breaking theory, which takes into account the heat of sublimation of the pure elements only, predicts enrichment of the surfaces in tin. Satisfactory agreement between theory and experiments is found for Pt3Sn. LEIS applied to 4 at. % Pd-Au and 5 at. % Ni-Au yields surface compositions of 0.8 at. % Pd and 1.0 at. % Ni respectively, in fair agreement with predictions from the bond-breaking theory. AES is not suited to detect this segregation. LEIS is found to be inapplicable for 14 at. % Pt-Au. For this alloy AES and selective COchemisorption yield a surface composition between 5 and 10 at. % Pt, whereas the bond-breaking theory predicts that the surface should contain as little as about 0.01 at. % Pt. A comparison of the results with contemporary theories on surface segregation is included.
Original languageEnglish
Pages (from-to)532-542
Number of pages11
JournalApplications of Surface Science
Issue number4
Publication statusPublished - 1979
Externally publishedYes


Dive into the research topics of 'Surface composition of some selected Group VIII/gold and Group VIII/tin alloys'. Together they form a unique fingerprint.

Cite this