LAUSR

(Ln1.8Fe0.2)FeSbO7 (Ln = Pr–Tb) mixed oxides have been synthesized via coprecipitation followed by annealing. According to Rietveld refinement results, all of the oxides have the pyrochlore structure (sp. gr. Fd\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar {3}$$\end{document}mz). The (Ln1.8Fe0.2)FeSbO7 compounds have been shown to exhibit high activity for CO oxidation reaction. The best results have been obtained for (Pr1.8Fe0.2)FeSbO7, which has a 90% CO conversion temperature T90 = 385°C. With increasing lanthanide atomic number, T90 rises monotonically from 385 to 550°C in going from Pr to Tb. This behavior is most likely due to the decrease of structural imperfection in the compounds with smaller lanthanide ionic radii.