TY - JOUR
T1 - Oxygen release behaviour of Ce(1-x)ZrxO2 powders and appearance of Ce(8-4y)Zr4yO(14-δ) solid solution in the ZrO2-CeO2-CeO1.5 system
AU - Izu, Noriya
AU - Omata, Takahisa
AU - Otsuka-Yao-Matsuo, Shinya
N1 - Funding Information:
The authors would like to express thanks to Mitsui Metal, for the supply of CeO 2 and ZrO 2 powders, and to Mr. H. Miyagishi for his experimental assistance. We are also grateful for the support of a Grant-in Aid for General Scientific Research (No. 09555225) from the Ministry of Education, Science and Culture, Japan.
PY - 1998/5/29
Y1 - 1998/5/29
N2 - To clarify the existence of metastable phases in the ZrO2-CeO2-CeO1.5 system, evolved-oxygen gas analyses, (EGA), by heating a single phase of t′ and t″ (Ce(1-x)ZrxO2) with various compositions, x, in a reducing gas and successive oxidation were carried out repeatedly. The oxygen release behaviour of the t′ and t′ phases was very complicated. The single κ phases, (Ce(1-x)ZrxO2) with the composition, x=0.5 and 0.6, which were obtained by oxidizing the resulting pyrochlore as a precursor in O2 gas at 873 K, exhibited a sharp oxygen release at the lowest temperature; the composition range of K phase may be x=0.45∼0.65. A new tetragonal phase t*, (Ce(1-x)ZrxO2), which was attained by cyclic redox process together with annealing in O2 gas at 1323 or 1423 K, exhibited a sharp oxygen release at the highest temperature; the composition range of t* phase may be as wide as x=0.20∼0.65. A metastable solid solution expressed by a chemical formula of Ce(8-4y)Zr4yO(14-δ) (y=0∼1) possessing a CaF2-related structure appeared on deoxidation of the t* phase. A ternary phase diagram containing the t* and Ce(8-4y)Zr4yO(14-δ) solid solution was proposed.
AB - To clarify the existence of metastable phases in the ZrO2-CeO2-CeO1.5 system, evolved-oxygen gas analyses, (EGA), by heating a single phase of t′ and t″ (Ce(1-x)ZrxO2) with various compositions, x, in a reducing gas and successive oxidation were carried out repeatedly. The oxygen release behaviour of the t′ and t′ phases was very complicated. The single κ phases, (Ce(1-x)ZrxO2) with the composition, x=0.5 and 0.6, which were obtained by oxidizing the resulting pyrochlore as a precursor in O2 gas at 873 K, exhibited a sharp oxygen release at the lowest temperature; the composition range of K phase may be x=0.45∼0.65. A new tetragonal phase t*, (Ce(1-x)ZrxO2), which was attained by cyclic redox process together with annealing in O2 gas at 1323 or 1423 K, exhibited a sharp oxygen release at the highest temperature; the composition range of t* phase may be as wide as x=0.20∼0.65. A metastable solid solution expressed by a chemical formula of Ce(8-4y)Zr4yO(14-δ) (y=0∼1) possessing a CaF2-related structure appeared on deoxidation of the t* phase. A ternary phase diagram containing the t* and Ce(8-4y)Zr4yO(14-δ) solid solution was proposed.
KW - CeO
KW - Cerium zirconate
KW - Oxygen release
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U2 - 10.1016/S0925-8388(98)00464-2
DO - 10.1016/S0925-8388(98)00464-2
M3 - Article
AN - SCOPUS:0032072298
VL - 270
SP - 107
EP - 114
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
IS - 1-2
ER -