Solid state reactions of nanocrystalline Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75} mixed oxide with high surface area silica in oxidizing and reducing atmosphere

Journal Article · Wed Aug 15 04:00:00 EDT 2012 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2012.04.020· OSTI ID:22131126

Malecka, Malgorzata A. ^[1]; Kepinski, Leszek ^[1]

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1. Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2 (Poland)

The interaction of nanocrystalline Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75} mixed oxide with a high surface amorphous silica support in an oxidizing and reducing atmosphere was studied by XRD, HRTEM, SAED, SEM and BET techniques. The Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75}-SiO{sub 2} system shows very high structural and size stability in the oxidizing atmosphere up to 1000 Degree-Sign C, but in hydrogen spreading of the oxide onto silica occurs at temperatures above 800 Degree-Sign C. In the oxidizing atmosphere stability of the mixed oxide is limited by extraction of ytterbium from the oxide driven by a tendency to form ytterbium silicates. A new polymorph of Yb silicate, isomorphic with y-Y{sub 2}Si{sub 2}O{sub 7} (yttrialite), has been identified in the samples containing the mixed Ce-Yb oxide. The absence of y-Yb{sub 2}Si{sub 2}O{sub 7} silicate in the Yb{sub 2}O{sub 3}-SiO{sub 2} samples treated in similar conditions indicates that Ce{sup 4+} ions are needed to stabilize the structure. - Graphical abstract: Structure evolution of nano-Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75}-SiO{sub 2} in air and in H{sub 2}. Highlights: Black-Right-Pointing-Pointer Nano-Ce{sub 0.50}Yb{sub 0.50}O{sub 1.75} on SiO{sub 2} is stable in air up to 1000 Degree-Sign C but spreads in hydrogen at 800 Degree-Sign C. Black-Right-Pointing-Pointer Formation of Yb silicates determines the stability of Ce{sub 0.50}Yb{sub 0.50}O{sub 1.75} at high temperatures. Black-Right-Pointing-Pointer New, y-Yb{sub 2}Si{sub 2}O{sub 7} silicate (yttrialite type) forms in Ce{sub 0.5}Yb{sub 0.5}O{sub 1.75}-SiO{sub 2} in H{sub 2} at 1100 Degree-Sign C.

• OSTI ID: 22131126
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 192; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
77 NANOSCIENCE AND NANOTECHNOLOGY
CERIUM IONS
CERIUM OXIDES
CRYSTALS
ELECTRON DIFFRACTION
HYDROGEN
NANOSTRUCTURES
SCANNING ELECTRON MICROSCOPY
SILICA
SILICATE MINERALS
SILICON OXIDES
SURFACE AREA
THORIUM MINERALS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
YTTERBIUM
YTTERBIUM OXIDES
YTTERBIUM SILICATES
YTTRIUM SILICATES