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Phase Separation in 12 mol% Ceria‐Doped Zirconia Induced by Heat Treatment in H 2 and Ar
Author(s) -
Zhu HaiYan,
Hirata Toshiya,
Muramatsu Yuji
Publication year - 1992
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1992.tb05514.x
Subject(s) - x ray photoelectron spectroscopy , tetragonal crystal system , analytical chemistry (journal) , raman spectroscopy , valence (chemistry) , materials science , monoclinic crystal system , cubic zirconia , phase (matter) , fourier transform infrared spectroscopy , crystallography , chemistry , ceramic , crystal structure , nuclear magnetic resonance , chemical engineering , chromatography , organic chemistry , engineering , composite material , physics , optics
The phase separation in 12 mol% CeO 2 ─ZrO 2 ceramic heattreated in a mixture of H 2 and Ar was investigated by X‐ray diffractometry (XRD), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and Raman scattering. After heat treatment at temperatures above 1200°C, the tetragonal solid‐solution phase separated into Zr 2 Ce 2 O 7 and the monoclinic phase. Raman scattering measurements also provided supplementary evidence for the phase separation. XPS showed that the valence change from Ce 4+ to Ce 3+ predominantly occurred, whereas the reduction from Zr 4+ to Zr 3+ took place above 1200°C. It is concluded, that in the highly reduced sample, where the valence changes from Ce 4+ (Zr 4+ ) to Ce 3+ (Zr 3+ ), the phase separation is noticeably promoted. Below 1000°C the phase separation was suppressed because of no appreciable valence change to trigger the phase separation, and the single tetragonal phase was retained.