Atmospheric Pressure Synthesis of Heavy Rare Earth Sesquioxides Nanoparticles of the Uncommon Monoclinic Phase
Abstract:We report, for the first time, the atmospheric pressure synthesis of nonagglomerated nanoparticles (20–60 nm in diameter) of the uncommon monoclinic phase of some heavy rare earth sesquioxides RE2O3 (RE=Dy, Ho, Er, Tm, and Yb). The RE2O3 nanoparticles, prepared by a flame synthesis process, were characterized by X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy. Monoclinic nanoparticles were formed when the flame temperature was sufficiently high; lower temperatures led to the formation of the normal cubic (C-type) phase. We explain the formation of the uncommon monoclinic phase on the basis of pressure–temperature phase equilibria, and the extra internal pressure induced by surface curvature of the nanoparticles.
Document Type: Research Article
Affiliations: 1: Department of Mechanical Engineering, Texas A&M University, College Station, Texas 77843 2: Department of Materials, ETH Zürich, 8093 Zürich, Switzerland 3: NEAT ORU and Thermochemistry Facility, University of California, Davis, Davis, California 95616 4: Department of Mechanical and Aeronautical Engineering, University of California, Davis, Davis, California 95616 5: Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, California 95616
Publication date: November 1, 2007