期刊
JOURNAL OF NANOPARTICLE RESEARCH
卷 11, 期 8, 页码 2113-2124出版社
SPRINGER
DOI: 10.1007/s11051-008-9577-7
关键词
Nanocrystalline ceria based oxide; CeO2-Lu2O3; CeO2-Yb2O3; Crystallite growth; Hydrogen; TEM; XANES; EBSD; Magnetic susceptibility
资金
- Polish Ministry of Science and Higher Education [N N205 0326 33]
The structure and phase evolution of nanocrystalline Ce1- x Ln (x) O2- x/2-delta (Ln = Yb, Lu, x = 0 - 1) oxides upon heating in H-2 was studied for the first time. Up to 950 A degrees C the samples were single-phase, with structure changing smoothly with x from fluorite type (F) to bixbyite type (C). For the Lu-doped samples heated at 1100 A degrees C in the air and H-2, phase separation into coexisting F- and C-type structures was observed for similar to 0.40 < x < similar to 0.70 and similar to 0.25 < x < similar to 0.70, respectively. It was found also that addition of Lu3+ and Yb3+ strongly hinders the crystallite growth of ceria during heat treatment at 800 and 950 A degrees C in both atmospheres. Valency of Ce and Yb in Ce0.1Lu0.9O1.55-delta and Ce0.95Yb0.05O1.975-delta samples heated at 1100 A degrees C was studied by XANES and magnetic measurements. In the former Ce was dominated by Ce4+, with small contribution of Ce3+ after heating in H-2. In the latter, Yb existed exclusively as 3+ in both O-2 and H-2.
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