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Journal of the Korean Ceramic Society 1990;27(5): 652. |
| 망간징크 페라이트 단결정의 산화-환원반응에 따른 미세구조의 변화 |
| 윤상영, 김문규 |
| 서울대학교 공과대학 무기재료공학과 |
| Microstructural Evoluation from the Oxidation-Reduction of Mn-Zn Ferrite Single Crystal |
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| ABSTRACT |
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Oxidation of Mn-Zn ferrite was made in air at various temperatures ranging from 400$^{circ}C$ to 1150$^{circ}C$. Subsequent reduction fo these oxidized samples was also made in air at 1300-1350$^{circ}C$ where the spinel phase of Mn-Zn ferrite is stable. Morphological observation revealed that the shape of precipitated hematite was plate or lath type on the close-packed habit plane of {111} ferrite which has a definite orientation relationship. The growth of precipitates showed the behavior fo parabolic dependence of the oxidating time. An apparent activation energy for the growth was found to be 125${pm}$3Kcal/mol. The fact that pores are observed along the precipitates illustrates the oxidation to occur dominantly by the counterdiffusion of cations and ction vacancies. For the reductio reaction pores are found to form at the site once occupied by the precipitates and at the surface. This observation illustrates that the oxygen volitalization from interior region to the surface is the dominant process for the reduction reaction. |
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