%0 Journal Article
%A Yashima, Masatomo
%A Sekikawa, Tomohiro
%A Sato, Daisuke
%A Nakano, Hiromi
%A Omoto, Kazuki
%D 2013
%T Crystal Structure and
Oxide-Ion Diffusion of Nanocrystalline,
Compositionally Homogeneous Ceria–Zirconia Ce0.5Zr0.5O2 up to 1176 K
%U https://acs.figshare.com/articles/journal_contribution/Crystal_Structure_and_Oxide_Ion_Diffusion_of_Nanocrystalline_Compositionally_Homogeneous_Ceria_Zirconia_Ce_sub_0_5_sub_Zr_sub_0_5_sub_O_sub_2_sub_up_to_1176_K/2445985
%R 10.1021/cg301530t.s001
%2 https://acs.figshare.com/ndownloader/files/4088653
%K nanocrystalline Ce 0.5Zr
%K bond valence sums
%K 1176 KThe crystal structure
%K bulk oxygen diffusivity
%K oxygen displacement
%K neutron diffraction study
%X The crystal structure, phase stability, and oxide-ion
diffusion
of nanocrystalline ceria–zirconia materials are unresolved
important issues, in particular at high temperatures, where the ceria–zirconia
catalysts work efficiently. Here, we report a high-temperature neutron
diffraction study of nanocrystalline [10.1(7) nm], compositionally
homogeneous, tetragonal Ce0.5Zr0.5O2. Contrary to the previous work, we have observed no tetragonal-to-cubic
phase transition in the nanocrystalline Ce0.5Zr0.5O2 up to 1176 K. The axial ratio c/aF and oxygen displacement along the c-axis from the fluorite regular 8c 1/4,1/4,1/4
position of the nanocrystalline Ce0.5Zr0.5O2 are almost independent of temperature. It was found that
the c/aF ratio and oxygen
displacement in nanocrystalline Ce0.5Zr0.5O2 are smaller than those of the bulk sample. It was shown that
the refined atomic displacement parameter and spatial (maximum entropy
method nuclear density) distribution of oxygen atom in nanocrystalline
Ce0.5Zr0.5O2 are larger than those
in nanocrystalline CeO2, which are factors of the high
bulk oxygen diffusivity and catalytic activity in nanocrystalline
Ce0.5Zr0.5O2. Possible diffusion
pathways of oxide ions along the fluorite ⟨100⟩ and
⟨110⟩ directions were visualized in the spatial distribution
of bond valence sums calculated using the present refined crystal
structure of nanocrystalline Ce0.5Zr0.5O2 at 1023 K. The diffusion path is not straight but curved
and forms a three-dimensional network.
%I ACS Publications