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KMID : 1059519860300010033
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Journal of the Korean Chemical Society
1986 Volume.30 No. 1 p.33 ~ p.39
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Nonstoichiometry of ZrO2 and Sm2O3
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Chang Soon-Ho
Yo Chul-Hyun
Choi Jae-Shi
Pyun Mu-Sil
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Abstract
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The x-values of nonstoichiometry chemical formulas, SmO1.5+x and ZrO2+x, have been measured in temperature range from 500℃ to 1000℃ under oxygen pressure of 2 × 10-1 to 1 × 10-5 atm by gravimetric method. The enthalpies of formation of defect in samarium sesquioxide and zirconium dioxide decrease with decreasing oxygen pressure and are all positive. The 1/n values calculated from the slopes of the plots of log x vs. log PO2 increase with temperature and are positive values which mean the higher oxygen pressure dependence at higher temperature. From x-values and thermodynamic data, it is found out that the nonstoichiometric defect is fully ionized metal vacancy. The conduction mechanisms of the systems are also discussed with respect to the nonstoichiometric compositions.
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