Short range order in bimetallic nanoalloys: An extended X-ray absorption fine structure study

Anatoly I. Frenkel, Qi Wang, Sergio I. Sanchez, Matthew W. Small, Ralph G. Nuzzo

Research output: Contribution to journalArticlepeer-review

Abstract

Partial coordination numbers measured by extended X-ray absorption fine structure (EXAFS) spectroscopy have been used for decades to resolve between different compositional motifs in bulk and nanoscale bimetallic alloys. Due to the ensemble-averaging nature of EXAFS, the values of the coordination numbers in nanoparticles cannot be simply interpreted in terms of the degree of alloying or segregation if the compositional distribution is broad. We demonstrate that a Cowley short range order parameter is an objective measure of either the segregation tendency (e.g., a core-shell type) or the degree of randomness (in homogeneous nanoalloys). This criterion can be used even in the case when the clusters are random but have broad compositional distributions. All cases are illustrated using the analyses of EXAFS data obtained in three different nanoscale bimetallic systems: Pt(core)-Pd(shell), Pd(core)-Pt(shell), and Pt-Pd random alloy.

Original languageEnglish (US)
Article number064202
JournalJournal of Chemical Physics
Volume138
Issue number6
DOIs
StatePublished - Feb 14 2013

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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