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Synchrotron X‐ray diffraction study of the tetragonal–cubic phase boundary of nanocrystalline ZrO 2 –CeO 2 synthesized by a gel‐combustion process
Author(s) -
Lamas D. G.,
Fuentes R. O.,
Fábregas I. O.,
Fernández de Rapp M. E.,
Lascalea G. E.,
Casanova J. R.,
Walsöe de Reca N. E.,
Craievich A. F.
Publication year - 2005
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889805025343
Subject(s) - tetragonal crystal system , nanocrystalline material , fluorite , crystallography , phase (matter) , materials science , diffractometer , phase boundary , synchrotron , crystal structure , x ray crystallography , analytical chemistry (journal) , diffraction , chemistry , optics , metallurgy , physics , organic chemistry , chromatography
The crystal structures of a number of nanocrystalline ZrO 2 –CeO 2 solid solutions, synthesized by a pH‐controlled nitrate‐glycine gel‐combustion process, were studied. By using a synchrotron X‐ray diffractometer, small peaks of the tetragonal phase, which correspond to forbidden reflections in the case of a perfect cubic fluorite structure, were clearly detected. By monitoring the most intense of these reflections, 112, as a function of the CeO 2 content, the tetragonal–cubic phase boundary was found to be at 85 (5) mol% CeO 2 . For a CeO 2 content up to 68 mol%, a tetragonal phase with c / a > 1 (known as the t ′ form) was detected, whereas, between 68 and 85 mol% CeO 2 , the existence of a tetragonal phase with c / a = 1 and oxygen anions displaced from their ideal positions in the cubic phase (the t ′′ form) was verified. Finally, solid solutions with higher CeO 2 contents exhibit the cubic fluorite‐type phase.