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Title: Epitaxial crystals of Bi{sub 2}Pt{sub 2}O{sub 7} pyrochlore through the transformation of δ–Bi{sub 2}O{sub 3} fluorite

Bi{sub 2}Pt{sub 2}O{sub 7} pyrochlore is thought to be one of the most promising oxide catalysts for application in fuel cell technology. Unfortunately, direct film growth of Bi{sub 2}Pt{sub 2}O{sub 7} has not yet been achieved, owing to the difficulty of oxidizing platinum metal in the precursor material to Pt{sup 4+}. In this work, in order to induce oxidation of the platinum, we annealed pulsed laser deposited films consisting of epitaxial δ–Bi{sub 2}O{sub 3} 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 Bi{sub 2}Pt{sub 2}O{sub 7}. 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–Bi{sub 2}O{sub 3} and Bi{sub 2}Pt{sub 2}O{sub 7} structures appears to facilitate the pyrochlore formation. These results provide the only route to date for the formation of epitaxial Bi{sub 2}Pt{sub 2}O{sub 7}.
Authors:
; ;  [1] ;  [2] ;  [3] ; ;  [2] ;  [4] ;  [1] ;  [3]
  1. School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States)
  2. Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853 (United States)
  3. (United States)
  4. Department of Physics and Astronomy, Ithaca College, Ithaca, New York 14850 (United States)
Publication Date:
OSTI Identifier:
22415260
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL materials; Journal Volume: 3; Journal Issue: 3; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; BISMUTH OXIDES; CATALYSTS; CRYSTAL GROWTH; CRYSTALS; EPITAXY; FILMS; FLUORITE; LASER RADIATION; OXIDATION; PLATINUM COMPOUNDS; PLATINUM IONS; PYROCHLORE; TRANSMISSION ELECTRON MICROSCOPY; VACANCIES; X-RAY DIFFRACTION