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Je, Hae-June;Kim, In-Tae;Hong, Kug-Sun
- Analytical Science and Technology
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- v.5 no.3
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- pp.327-332
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- 1992
Mn-Zn ferrite single crystals show some fluctuations in composition along the direction of growth by the conventional Bridgman method. The single crystal with a uniform composition was obtained by maintaining the liquid composition content. For example, two batches of powder were prepared : one is consisted of 52 mol% of $Fe_2O_3$, 30 mol% of MnO, and 18 mol% Zn(Composition A), and the other 53 mol% of $Fe_2O_3$, 28.5 mol% of MnO, and 18.5 mol% ZnO(Composition B). Crack-free single crystals with the uniform composition B were grown in a size of 60mm diameter, 300mm long by melting the pellets of composition A and followed by supplying the composition B as tablets. Initial permeabilities were obtained above 600 at 5 MHz in the region of 30~270 mm along the direction of growth.
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김태옥
- Journal of the Korean Ceramic Society
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- v.13 no.3
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- pp.13-20
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- 1976
The magnetic properties, especially the magnetostriction, of ferroxplana $Zn_{1-x}$$M_X$Y(x=0.0, 0.2, 0.4, 0.6) were investigated at room temperature. In general, the Curie temperature and the permeability of ferroxplana $Zn_{1-X}$$Mn_X$Y increased while the amount of the other phase decrease with increased concentration of dopant $Mn^{2+} for $Zn^{2+}. The magnetostriction constnats K1, K2, K3 and K4 for ZnY were ＋0.3, -5.0, -4.3 and $-4.8{\times}$$10^{-6} while that for 4Zn^0.8$ $Mn^0.2$Y were ＋2.5, -5.4, -6.0 and $-3.4{\times}10^{-6}$, respectively.
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정재우;오근호
- Journal of the Korean Crystal Growth and Crystal Technology
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- v.2 no.1
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- pp.10-19
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- 1992
Mn - Zn Ferrite has physical properties of the high initial permeability, saturation magnetic flux density, and low loss factor as a representative magnetic material of soft ferrites, in addition the mechanical property is excellent as a single crystal. Therefore it is important electronic components and used for VTR Head. Mn - Zn Ferrite single crystals with the diameter 8mm were grown in atmosphere mixed with $O_2$ and Ar gas by the Floating Zone(FZ) method that impurities can not be incorporated to the crystals because of not-using the crucible to put in the melt, and the sharp temperature gradient results from making a focus at one point utilizing the infrared ray emitted from the halogen lamp as a heat source. During the crystal growing, the highest temperature of melting area was maintained to be $1650^{\circ}C$, growth rate and rotation rate were 10 mm/hr, 20 rpm respectively. The phases and the growth directions of crystals were determined from the analysis of X RD patterns, Laue, TEM diffraction patterns and etch pit shapes were observed by the optical microscope through the chemical etching. The corelation of optimum conditions for acquiring the better crystals was found out with the growth rate, the length and diameter of melt at the interface according to the diameter of feed rod, and the patterns of growing interface also studied.
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김동일;옥승민;송재만;김기만;신승재;문상현
- The Journal of Korean Institute of Electromagnetic Engineering and Science
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- v.15 no.4
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- pp.406-413
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- 2004
In this study, we investigated the reflection coefficient of absorbers fur mobile phone on average Particle size and preparation temperature of specimens. We used recycled MnZn ferrite with initial permeability of 2,500 and 10,000 as starting materials. Absorption ability increased at 1.8 ㎓ which is frequency fur mobile phones with increasing average particle size. We developed a sheet type electromagnetic wave absorber with the thickness of 1 mm which showed reflection coefficient of -3.8 ㏈ at 1.8 ㎓.
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