Nonstoichiometry of $ZrO_2$ and $Sm_2O_3$

$ZrO_2$$Sm_2O_3$의 비화학양론

  • Soon Ho Chang (Department of Chemistry, Yonsei University) ;
  • Chul Hyun Yo (Department of Chemistry, Yonsei University) ;
  • Jae Shi Choi (Department of Chemistry, Yonsei University) ;
  • Mu Sil Pyon (Department of Chemical Engineering, Myongji University)
  • 장순호 (연세대학교 이과대학 화학과) ;
  • 여철현 (연세대학교 이과대학 화학과) ;
  • 최재시 (연세대학교 이과대학 화학과) ;
  • 편무실 (명지대학교 공과대학 화학공학과)
  • Published : 1986.02.20

Abstract

The x-values of nonstoichiometry chemical formulas, Sm$O_{1.5+x}$ and Zr$O_{2+x}$, have been measured in temperature range from 500$^{\circ}$C to 1000$^{\circ}$C under oxygen pressure of 2 ${\times}10^{-1}$ to 1 ${\times}10^{-5}$ 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 $PO_2$ 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.

Keywords

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