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【期刊论文】Thermodynamic assessment of the Fe-Er system
刘仲武, G.J. Zhou a, b, Z.W. Liu a, D.C. Zeng a, n, Z.P. Jin b
Physica B, 405 (2010): 3590–3593,-0001,():
-1年11月30日
The Fe–Er binary system has been assessed by combining CALPHAD method with Miedema approach. Liquid is treated as a substitutional solution phase, of which the excess Gibbs energies are modeled by a Redlich–Kister polynomial function. The binary intermetallic compounds are treated as stoichiometric phases. Thermodynamic parameters of various phases have been optimized and the calculated results are in reasonable agreement with experimental data.
Thermodynamic calculation, Fe-Er system, Miedema method, Phase diagram
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【期刊论文】The high frequency magnetic properties of self assembled Fe-Co-Si-N nanogranular thin films
刘仲武, Yan Liu · R.V. Ramanujan · Z.W. Liu · C.Y. Tan · Xing Zhao · Erjia Liu · C.K. Ong
Appl Phys A, (2010) 100: 257-263,-0001,():
-1年11月30日
The effect of a variation in Si and N concentration on the microstructure, crystal structure and high-frequency magnetic properties of Fe-Co-Si-N nanogranular thin films was investigated. The films, prepared by rf magnetron sputtering, consisted of nanosized grains of FeCo as well as a Si and N rich intergranular amorphous phase. The Si concentration had a significant effect on the crystal structure of the FeCo phase. The resistivities of the Fe-Co-Si-N films were significantly enhanced by an increase in Si concentration. The resonant frequency of the Fe-Co-Si-N films could be tuned from 0.45 GHz to 2.1 GHz by controlling Si concentration. The N concentration greatly influenced magnetic properties and the variation in resonant frequency is in agreement with Kittel's equation.
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【期刊论文】Tb0.3 Dy0.7 Fe2单晶中巨磁致伸缩的逆效应*
刘仲武, 张辉, 曾德长
物理学报,2010,59(4):2808~2814,-0001,():
-1年11月30日
研究了Terfenol-D材料中巨磁致伸缩的逆效应,即磁机械效应。基于Stoner-Wohlfarth(SW)模型,考虑磁晶各向异性和应力各向异性能,依据自由能极小原理,获得了退磁态下Terfenol-D单晶中磁化强度方向和压应力的关系.采用数值方法求解了平衡条件下的非线性方程组。理论结果表明,Terfenol-D巨磁致伸缩单晶中的磁各向异性取决于磁晶各向异性和应力各向异性之间的竞争。在压应力的作用下,Terfenol-D单晶中的磁各向异性由立方向单轴转变。理论和实验结果的比较表明,存在一个临界压应力,使磁致伸缩效应达到极大值。该理论结果还解释了压应力使得Terfenol-D单晶材料难于磁化和磁致伸缩效应出现极大值的实验事实。理论计算不仅为研究这类问题提供了一个更准确的方法,而且其结果也有助于理解类似材料中的磁化过程。
Terfenol-D,, 磁机械效应,, 巨磁致伸缩效应., 磁各向异性
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【期刊论文】Synthesis, growth mechanism and gas-sensing properties of large-scale CuO nanowires
刘仲武, M.L. Zhong, D.C. Zeng, Z.W. Liu *, H.Y. Yu, X.C. Zhong, W.Q. Qiu
Acta Materialia, 58 (2010): 5926-5932,-0001,():
-1年11月30日
Large-scale CuO nanowires were in situ grown on Cu substrate by a very simple catalyst-free thermal oxidation process in atmosphere. The structure characterization revealed that these nanowires are monoclinic structured single crystallites with mean diameters of 60–200 nm. The effects of growth time and temperature on the morphology of the nanowires were investigated. It is found that the growth time has an important effect on the length and density of the nanowires, whereas the growth temperature has a distinct influence on the nanowire diameter. Different from the vapor–solid (V–S) mechanism, the growth of nanowires is found to be based on the Cu ion diffusion. The ethanol-sensing properties of these CuO nanowires were also studied based on a self-designed prototype and the results indicated that these large-scale nanowires are indeed a good candidate for gas-sensing applications.
Nanostructures, CuO nanowires, Thermal oxidation, Gas-sensing properties
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【期刊论文】Rigid and flexible Fe-Zr-N magnetic thin films for microwave absorber
刘仲武, Z. W. Liu, , a D. C. Zeng, R. V. Ramanujan, and C. K. Ong
JOURNAL OF APPLIED PHYSICS 107, 09A505 (2010),-0001,():
-1年11月30日
FeZrN thin films with in-plane anisotropy were deposited on both rigid substrate Si and flexible substrate Kapton by magnetron sputtering. The as-prepared films had the microstructure of nanocrystallites with a small amount of intergranular amorphous phase. The thickness dependent coercivity showed different behaviors for flexible and rigid films. The dynamic magnetic properties of the films have been characterized. Although the high frequency characteristics are closely related to the thickness, composition, and anisotropy, the flexible films have relatively smaller values of real permeability but larger values of ferromagnetic resonance frequency fr than the rigid films. Due to the flexibility, the properties of the flexible films varied with each other. Nevertheless, both rigid and flexible films can find important applications in microwave absorber due to their excellent high frequency properties up to 5 GHz. © 2010 American Institute of Physics. doi:10.1063/1.3337684
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