High frequency behaviours and Mossbauer study of field annealed FeCuNbSiB alloy ribbons

This paper investigates the high frequency behaviours and magnetic anisotropy of rapidly solidified FINEMET （Fe73.5Si13.sBgNb3Cul） alloy ribbons annealed in an applied magnetic field. It finds that the ribbons annealed with the applied magnetic field show much higher resonance frequencies and have even higher permeability at higher frequencies than the samples annealed without the magnetic field and the non-annealed ribbons. MSssbauer spectroscopy had been employed to study the spatial distribution of the magnetic moments of five selected FINEMET alloy ribbons in different heat-treated conditions. The results show that an easy plane has been established after annealling in the magnetic field, while for the other ribbons this effect is not significant. Hence, the relationship between magnetic field annealing and high frequency property has been bridged by the bianisotropic theory.     

Electronic structures and magnetocrystalline anisotropy energies of ordered Co1-xNix alloys: a first principles study

The electronic structures and magnetocrystalline anisotropy(MA) of ordered hexagonal close-packed(hcp) Co1-xNix alloys are studied using the full-potential linear-augmented-plane-wave(FLAPW) method with generalized gradient approximation(GGA).Great changes of magnetocrystalline anisotropy energy(MAE) are gained with different Ni compositions.Also,in-plane magnetocrystalline anisotropy is obtained for Co 15 Ni in which the Snoek’s limit is exceeded.It is found that the changes of the symmetry of the crystal field on Ni induce small variations in band structures around the Fermi level under different compositions,which plays an important role in modulating the magnetization direction,where the hybridization between Co-3d and Ni-3d orbits is of special importance in deciding the magnetocrystalline anisotropy of itinerant states.The rigid-band model is inapplicable to explain the evolution of magnetocrystalline anisotropy energy with Ni composition,and it is also inadequate to predict the magnetocrystalline anisotropy energy through the anisotropy of the orbital magnetic moment.     

功率半导体器件走上前台从量变到质变成为节能主角

最近两年，功率半导体器件市场需求持续旺盛。而且，旺销的产品都是用于白色家电变频化的功率半导体器件及其模块。三洋电机公司和美国国际整流器公司曾于2003年10月合资成立了IRSA集成技术公司，专门从事面向白色家电的变频器模块的开发业务。     

零外接加速手机调频收音机模块小型化竞争

2004年8月,三洋公司开发了用于手机的FM(调频)收音机(调谐器)芯片。该芯片省去了所有外接元件,外形尺寸仅5mm2。目前用于手机的FM收音机芯片,由于需要电感器和变容二极管等25个外接元件,模块组装面积高达150mm2。因而,业界开发了完全不需要外接元件的单芯片产品,其组装面积为25     

CoFe2O4纳米颗粒的结构、磁性以及离子迁移

聚乙烯醇(PVA)溶胶凝胶法制备出CoFe₂O₄纳米微粉，用X射线衍射研究了铁氧体纳米颗粒的结构.测量了CoFe₂O₄纳米颗粒80—873 K的变温穆斯堡尔谱，发现纳米颗粒的磁转变温度范围为793—813 K，比块体材料的磁性转变温度要低.CoFe₂O₄纳米颗粒的德拜温度θ_A=674 K，θ_B=243 K，比块体材料要小.CoFe₂O₄纳米颗粒超精细场H_f随温度的变化符合T^3/2+T^5/2定理.当温度较高时，平均同质异能移IS随温度的升高而减小，并呈线性关系. 关键词： 纳米颗粒 磁性 穆斯堡尔谱     

Substrate Dependence of Properties of Sputtered ITO Films

High-quality indium-tin-oxide (ITO) films are deposited on p-type Czochralski silicon and 7059 Coming glass by direct-current magnetron sputtering at various temperatures. The structural, electrical and optical properties of the ITO films are investigated as functions of the substrate temperature. A comparison between the characteristics of the ITO films on silicon and Coming glass is presented. The results show that for the ITO film on silicon,the nucleation begins from room temperature; the resistivity reaches a maximum value at 75℃; the reflectivity increases with increasing temperature; when temperature is above 125℃, the ITO grows in a three-dimensional manner and forms a granular structure. However, for the ITO film on glass, it is still in an amorphous state at 75℃. Moreover, both the resistivity and the reflectivity decrease with increasing temperature. Above 125℃, the ITO grows in a two-dimensional manner and forms a domain structure.     

Remanence Properties and Magnetization Reversal Mechanism of Fe Nanowire Arrays

Remanence properties and magnetization reversal mechanism of Fe nanowire arrays with diameters 16nm and 130nm are studied. Isothermal remanent magnetization curves show that the contribution of irreversible magnetization decreases when the diameter changes from 16nm to 130hm. The remanence coercivities of these nanowires obtained in dc-demagnetization curve are about 2400 Oe and 800 Oe, respectively. The magnetization reversal mechanism is different in these two samples. For the nanowire array with diameter 16nm, both the nucleation and the pinning have effects on magnetization reversal mechanism, and the pinning field (about 2500 Oe) is larger than the nucleation field (about 2200 Oe). However, for the nanowire array with diameter 130nm, the magnetization reversal mechanism is dominated by the pinning effect of domain walls.     

H2O2氧化法制备Fe3O4纳米颗粒及与共沉淀法制备该样品的比较

在近中性条件下，利用H₂Ｏ₂氧化Fe(OH)2胶体成功制备了Fe₃ Ｏ₄纳米颗粒.分别利用透射电镜(TEM)，x射线衍射仪(XRD)，振动样品磁强计(VSM)和超导量子干涉仪（SQUI D）对样品的形貌，结构，宏观磁性进行了表征和测量.TEM图像表明样品为球形颗粒，直径 大小约18nm，且分布较均匀.XRD结果表明样品为立方尖晶石结构.穆斯堡尔谱测量表明样品 室温下对应两套六线谱，样品的晶体结构存在缺陷，内磁场略小于块体Fe₃Ｏ4的值. 宏观磁测量表明样品的饱和磁化强度可达67×10^-3A·m²/g，在20 K出现了Verw ey转变.选择该法制备的Fe₃Ｏ₄纳米颗粒与共沉淀法得到的样品作 了磁性比较.宏观磁 测量表明共沉淀法制备的样品在外磁场为1T时仍未饱和，磁化强度仅为46×10^-3A·m²/g，在178K出现了超顺磁转变温度，且在测量温度范围内没有发现Verwe y转变. 关键词： 亚铁磁 超顺磁 穆斯堡尔谱     

问题产品不断出现急需重新进行可靠性评估

今年初,SONY宣布对2002年11月至2003年8月间生产的1万多台32英寸KE-32TS2 PDP电视提供免费维修.因为这批电视在播放时经常不能显示图像,原因是驱动PDP的电源电路板存在问题.     

基于SOPC的八路高速数据采集系统

随着信息领域各技术的发展,数据釆集方面也取得了长足的进步,釆集数据的信息化是目前社会发展的主流方向,各种领域都用得到数据采集。随着实时测控系统被广泛的应用,以嵌入式为核心的数据采集系统已在测控领域中占到统治地位。本文研究如何利用SOPC技术来设计实现多路数据采集系统。嵌入式软核处理器、采集数据处理部分和LCD显示是系统设计中的三个重要部分。系统中嵌入式软核CPU的设计,运用Nios II嵌入式软核处理器控制数据釆集系统工作,达到系统设计任务和要求。