Certain pyrochlore oxides are among the best oxygen catalysts in alkaline media. Hence, exploring epitaxial films of these materials is of great fundamental and technological interest. Unfortunately, direct film growth of one of the most promising pyrochlores, 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 annealed films are the first epitaxial crystals of Bi2Pt2O7. We also visualized the pyrochlore structure by scanning transmission electron microscopy, and observed ordered cation vacancies in a bismuth-rich film but not in a platinum-rich film. The similarity between the δ-Bi2O3 and Bi2Pt2O7 structures appears to facilitate the pyrochlore formation. These results constitute a new approach for synthesis of novel pyrochlore thin film oxygen catalysts.
@article{arxiv.1410.2307,
title = {Epitaxial growth of Bi$_2$Pt$_2$O$_7$ pyrochlore},
author = {Araceli Gutierrez-Llorente and Howie Joress and Arthur Woll and Megan E. Holtz and Matthew J. Ward and Matthew C. Sullivan and David A. Muller and Joel D. Brock},
journal= {arXiv preprint arXiv:1410.2307},
year = {2014}
}