巻号一覧
71 巻, 4 号
選択された号の論文の8件中1～8を表示しています
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論説
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加藤 宏朗, 宮崎 照宣原稿種別: 総説
専門分野: 電子材料
2000 年 71 巻 4 号 p. 271
発行日: 2000年
公開日: 2001/03/01
ジャーナル フリーA modeling method for calculating magnetic properties of Nd2Fe14B-type intermetallics has been introduced based upon the crystalline-electric-field interaction at the Nd ions and exchange interaction between Nd and Fe sublattices. Next, as an extension of this modeling, experimental results of magnetostriction measurements in the vicinity of spin-reorientation transition in (Er-Tb)2Fe14B system was presented, which have been quantitatively understood by the calculation. In these cases, the magnetic anisotropy and the magnetization are dominated separately by the rare-earth and Fe sublattices, respectively, within a unit cell. The third part of this article is dedicated to a topics of hard / soft nanocomposite magnets, which can be regarded as an extension of the two sublattice model in larger length scale. Magnetic properties of nanocomposite Nd2Fe14B / a-Fe multilayer thin films were investigated and discussed in conjunction with the micromagnetic calculations.抄録全体を表示PDF形式でダウンロード (138K) -
齋藤 章彦, 西方 敦博原稿種別: 総説
専門分野: 電子材料
2000 年 71 巻 4 号 p. 279
発行日: 2000年
公開日: 2001/03/01
ジャーナル フリーAs the number of systems using high frequency electromagnetic waves has increased in recent years, such as IMT-2000 system, electromagnetic compatibility (EMC) problems have become apparent.抄録全体を表示PDF形式でダウンロード (653K) -
斉藤 貴伸, 武本 聡原稿種別: 研究論文
専門分野: 電子材料
2000 年 71 巻 4 号 p. 287
発行日: 2000年
公開日: 2001/03/01
ジャーナル フリーMagnetic powder cores are widely used for smoothing and boost choke coils of switching regulators as well as DC-DC converters. However , in general powder cores have a disadvantage of large core loss compared to sintered soft ferrite cores , and lower core loss powder cores are strongly required. In this study effects of particle size and microstructure on core loss of powder cores with Fe-Si-Al water-atomized and modified water-atomized powders were investigated. We concluded as follows.(1) Both eddy current loss and hysteresis loss are small for modified water-atomized powder cores compared with water-atomized cores. (2) Eddy current loss decreases with being particle size small. (3) Modified water-atomized powder cores have low eddy current loss through higher resistivity than that of water atomized powder cores. (4) Crystal grains are large for modified water atomized powder cores , thus hysteresis loss is small. It is guessed that aluminum oxides included in water atomized powder prevent grain growth through images with electron probe micro analyzer.抄録全体を表示PDF形式でダウンロード (607K) -
入山 恭彦, 大河内 敬雄, 藤田 雄一郎原稿種別: 総説
専門分野: 電子材料
2000 年 71 巻 4 号 p. 295
発行日: 2000年
公開日: 2001/03/01
ジャーナル フリーSm-Fe-N hard magnetic materials are good candidates for high performance bonded magnets. Rapid-quenching method should be highly favorable for the fabrication of isotropic magnet powder with high coercivity. We report here the magnetic properties of Sm-Fe-N powders produced by three kinds of rapid-quenching processes. Sm2Fe17 powders were prepared by gas-atomization (GA), rotating-disk atomization (RDA), and melt-spinning (MS) methods. The Sm2Fe17 GA powder had dendritic solidification structure, while the RDA powder had microcrystalline structure with size of 3-5μm. Coercivities (HcJ ) of their nitrides were 56 (for GA) and 217 kA/m (for RDA). The HcJ of nitrided Sm2Fe17 MS powder with wheel velocity (Vs) of 5-20 m/s, which had also microcrystalline structure, was 53 to 509 kA/m. These coercivity values are not sufficient for practical value (600 kA/m) for bonded magnet applications. From the study of additive effects, it was found that C, C-Si, C-Ga, or C-Al addition decreased the grain size of quenched Sm2Fe17 powder. Consequently, high coercivity was obtained; the HcJ of nitrided Sm2Fe15C1Si1 MS powder with Vs of 10 m/s was 898 kA/m, and 708 kA/m for the nitrided Sm2Fe15C1Si1 RDA powder. The compression-molded bonded magnet made from Sm2Fe18Si0.1Nx MS powder showed a high (BH)max of 82.7 kJ/m3.抄録全体を表示PDF形式でダウンロード (753K) -
荒木 建次, 山口 真史原稿種別: 総説
専門分野: 電子材料
2000 年 71 巻 4 号 p. 303
発行日: 2000年
公開日: 2001/03/01
ジャーナル フリーObviously, concentrator solar cells reduce the total area of cells required, which provides lower system costs. For non-concentrator solar panels, the solar cells represent 80% of the system cost. The use of concentrator cells provides a cost reduction for cells inversely proportional to the concentration ratio. However conventional Si concentrator cells normally require more complex photolithography which increases the cost of manufacture. In this novel approach a single step photolithography process is described which includes superfine random pyramid texture, with the electrode directly defined onto the textured surface. Additionally, improved electrode design was applied, allowing for operation under non-uniform surface voltage and current density, experienced during high concentrator conditions. This has lead to energy conversion efficiencies in excess of 19%. Experimental results on the conversion efficiency are in good agreement with the results calculated by the proposed equations taking into account of the distributed diode effect at high concentration ratio.抄録全体を表示PDF形式でダウンロード (658K)
解説
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田口 常正原稿種別: 技術報告
専門分野: 電子材料
2000 年 71 巻 4 号 p. 311
発行日: 2000年
公開日: 2001/03/01
ジャーナル フリーThe technology of white LEDs which is connected with the InxGa1-xN blue LED coated with a YAG : Ce phosphor, has improved the white LED efficiencies to approximately 30 lm/W. We have reported a maximum luminous efficacy of about 40 lm/W using 700 LEDs lighting source at electric power of 5 W. It has been expected that extremely high-brightness white LEDs can significantly replace standard incandescent bulbs. We have also demonstrated an energy saving type street lamp linked with a photovoltaic solar cell using a 10 Cd-class white LEDs array lighting source. An alternative method of making a color conversion white LEDs is provided to produce a true white which can be achieved using three colors from red, green, and blue phosphors excited by ultraviolet (UV) LEDs. In the future, as the efficiency of blue and UV LEDs will be improved, the white LED lamps may replace conventional light bulbs or fluorescent lamps in many applications.抄録全体を表示PDF形式でダウンロード (133K) -
西方 敦博原稿種別: 技術報告
専門分野: 電子材料
2000 年 71 巻 4 号 p. 321
発行日: 2000年
公開日: 2001/03/01
ジャーナル フリーEMC -- the concept of harmonization of the society bearing as many electronics equipments -- is outlined. In addition, some topics on the electromagnetic shielding are introduced, concerning the problem on the evaluation of shielding materials and on the resonance of shielding enclosures.抄録全体を表示PDF形式でダウンロード (126K)
技術資料
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西尾 孝幸, 入山 恭彦原稿種別: 研究論文
専門分野: 電子材料
2000 年 71 巻 4 号 p. 327
発行日: 2000年
公開日: 2001/03/01
ジャーナル フリーIt is necessary for material suppliers to know a relationship between specifications of device and those of materials used, in order to develop a suitable material for the target device. A computer simulation is one of the effective methods for this purpose. In this paper, an example of static magnetic field analysis on DC brushless motor for hard disc drive (HDD) is shown.抄録全体を表示PDF形式でダウンロード (1083K)
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