Crystal Structure and Phase Relationships in the Reduced-Reoxidized Ceria-Zirconia Solid Solution

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The crystal structures of reduced-reoxidized ceria-zirconia solid solutions, Ce2Zr2O7+x, with an ordered arrangement of Ce and Zr ions were studied by transmission electron microscopy (TEM), X-ray powder diffraction and thermogravimetric analysis. The oxygen absorption of Ce2Zr2O7 with pyrochlore structure (space group m Fd 3 ) was revealed to proceed through two-step reaction; reaction from Ce2Zr2O7 to b-Ce2Zr2O7.5 around 400K and reaction from b-Ce2Zr2O7.5 to Ce2Zr2O8 about 600K. b-Ce2Zr2O7.5 phase with space group m F 3 4 was thought to be formed by occupation of the half ordered oxygen vacancies with oxygen ions periodically. The oxidation from Ce2Zr2O7 to b-Ce2Zr2O7.5 was also occurred at room temperature by keeping for about 1 year or by irradiation of an electron beam in TEM. On the other hand, the crystal structure of Ce2Zr2O8, completely oxidized state of Ce2Zr2O7, belongs to the space group of m P 3 4 or 23 P from the rule for possible diffractions and the symmetry of the ordering cations.

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Periodical:

Materials Science Forum (Volumes 475-479)

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Edited by:

Z.Y. Zhong, H. Saka, T.H. Kim, E.A. Holm, Y.F. Han and X.S. Xie

Pages:

1351-1354

DOI:

10.4028/www.scientific.net/MSF.475-479.1351

Citation:

T. Sasaki et al., "Crystal Structure and Phase Relationships in the Reduced-Reoxidized Ceria-Zirconia Solid Solution", Materials Science Forum, Vols. 475-479, pp. 1351-1354, 2005

Online since:

January 2005

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$35.00

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[100] direction (a) at the start of irradiation of an electron beam, (b) after 3 minutes of irradiation. Fig. 5 Lattice images and electron diffraction patterns of (a)Ce2Zr2O7, (b)β-Ce2Zr2O7. 5, (c)Ce2Zr2O8, a: lattice constant(~1nm) , d: length of periodicity.

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