| 육방정 페라이트의 결정과 Block 구조 |
| 신형섭 |
| 가야대학교 안경광학과 |
| Crystal and Block Structures of Hexagonal Ferrites |
| Hyung-Sup Shin |
| Department of Ophthalmic Optics, Kaya University |
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| ABSTRACT |
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It has been studied the crystal and block structures of the hexagonal ferrites with M, W, Y and Z types prepared by various coprecipitation-oxidation method. The structures have been refined with a Rietveld analysis of the powder X-ray diffraction pattern with high precision ($R_{WP}$ <0.09, $R_I$ <0.03). The density difference between the S-blocks was proportioned to the cobalt contents in hexagonal ferrites, but that between the R or T-blocks was relatively small. Compared with the blocks and cation-oxygen polyhedra in BaM ($BaFe_{12}O_{19}$), those were bulky to the normal direction for the c-axis in $Co_2W$ ($BaCo_2Fe_{16}O_{27}$) and to the parallel direction for the c-axis in $Co_2Y$ ($Ba_2Co_2Fe_{12}O_{22}$) and $Co_2Z$ ($Ba_3Co_2Fe_{24}O_{41}$). The S-blocks of $Co_2W$, $Co_2Y$, and $Co_2Z$ were unstable and distorted. Because the T-block of $Co_2Z$ was unstable, the T-block was decomposed into the Ba-rich phase and $Co_2W$ at high temperatures above $1200^{circ}C$. A standard powder X-ray diffraction pattern for $Co_2Z$ was proposed as well. |
| Key words:
Hexagonal ferrite, Rietveld analysis, Crystal structure, Block structure |
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