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Title: Epitaxial crystals of Bi₂Pt₂O₇ pyrochlore through the transformation of δ–Bi₂O₃ fluorite

Bi₂Pt₂O₇ pyrochlore is thought to be one of the most promising oxide catalysts for application in fuel cell technology. Unfortunately, direct film growth of Bi₂Pt₂O₇ has not yet been achieved, owing to the difficulty of oxidizing platinum metal in the precursor material to Pt⁴⁺. In this work, in order to induce oxidation of the platinum, we annealed pulsed laser deposited films consisting of epitaxial δ–Bi₂O₃ and co-deposited, comparatively disordered platinum. We present synchrotron x-ray diffraction results that show the nonuniform annealed films contain the first epitaxial crystals of Bi₂Pt₂O₇. We also visualized the pyrochlore structure by scanning transmission electron microscopy, and observed ordered cation vacancies in the epitaxial crystals formed in a bismuth-rich film but not in those formed in a platinum-rich film. The similarity between the δ–Bi₂O₃ and Bi₂Pt₂O₇ structures appears to facilitate the pyrochlore formation. These results provide the only route to date for the formation of epitaxial Bi₂Pt₂O₇.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. Cornell Univ., Ithaca, NY (United States)
  2. Ithaca College, Ithaca, NY (United States)
Publication Date:
OSTI Identifier:
1203554
Grant/Contract Number:
SC0001086
Type:
Accepted Manuscript
Journal Name:
APL Materials
Additional Journal Information:
Journal Volume: 3; Journal Issue: 3; Journal ID: ISSN 2166-532X
Publisher:
American Institute of Physics (AIP)
Research Org:
Cornell Univ., Ithaca, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 30 DIRECT ENERGY CONVERSION