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Journal of the Korean Ceramic Society 1994;31(12): 1491. |
전하적정법에 의한 $(Mg_{0.29}Fe_{0.71})_{3-}deltaO_4$ 훼라이트의 Nonstoichiometry$(delta)$와 상안정 영역 결정 |
강선호, 유한일, 강대석1, 유병두1 |
서울대학교 무기재료공학과 1국방과학기술연구소 |
Determination of Nonstoichiometry$(delta)$and Phase Stability Region of $(Mg_{0.29}Fe_{0.71})_{3-}deltaO_4$ by a Coulometric Titration Method |
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ABSTRACT |
Nonstoichiometry($delta$) and the phase stability region of a ferrite spinel (Mg0.29Fe0.71)3-$delta$O4 have been investigated by a coulometric titration method as a function of temperature(T) and oxygen partial pressure(Po2). It has been found that the spinel is thermodynamically stable in the ranges -8.0$leq$log(PO2/atm)$leq$-2.4, -7.0$leq$log(PO2/atm)$leq$-1.7 respectvely at 100$0^{circ}C$. The nonstoichiometry extends over the ranges of -0.004$leq$$delta$$leq$0.007, -0.008$leq$$delta$$leq$0.006, -0.033$leq$$delta$$leq$0.004 at 100$0^{circ}C$, 120$0^{circ}C$, respectvely. The observed PO2-dependence of $delta$ suggests that the majority ionic defects are cation interstitials in the low PO2 region and cation vacancies in the high PO2 region. |
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