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Search Results: 1 - 10 of 274794 matches for " H. B. Nie "
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Critical Percolation Probabilities for the Next-Nearest-Neighboring Site Problems on Sierpinski Carpets
H. B. Nie,B. M. Yu,K. L. Yao
Physics , 2003,
Abstract: In this paper, we compute the next-nearest-neighboring site percolation (Connections exist not only between nearest-neighboring sites, but also between next-nearest-neighboring sites.) probabilities Pc on the two-dimensional Sierpinski carpets, using the translational-dilation method and Monte Carlo technique. We obtain a relation among Pc, fractal dimensionality D and connectivity Q. For the family of carpets with central cutouts,, where, the critical percolation probability for the next-nearest-neighboring site problem on square lattice. As D reaches 2, which is in agreement with the critical percolation probability on 2-d square lattices with next-nearest-neighboring interactions.
Giant magnetoimpedance in crystalline Mumetal
H. B. Nie,A. B. Pakhomov,X. Yan,X. X. Zhang,M. Knobel
Physics , 2003, DOI: 10.1016/S0038-1098(99)00350-6
Abstract: We studied giant magnetoimpedance (GMI) effect in commercial crystalline Mumetal, with the emphasis to sample thickness dependence and annealing effects. By using appropriate heat treatment one can achieve GMI ratios as high as 310%, and field sensitivity of about 20%/Oe, which is comparable to the best GMI characteristics obtained for amorphous and nanocrystalline soft magnetic materials.
Evolution of In-Plane Magnetic Anisotropy In Sputtered FeTaN/TaN/FeTaN Sandwich Films
H. B. Nie,C. K. Ong,J. P. Wang,Z. W. Li
Physics , 2003, DOI: 10.1063/1.1555365
Abstract: FeTaN/TaN/FeTaN sandwich films, FeTaN/TaN and TaN/FeTaN bilayers were synthesized by using RF magnetron sputtering. The magnetic properties, crystalline structures, microstructures and surface morphologies of the as-deposited samples were characterized using angle-resolved M-H loop tracer, VSM, XRD, TEM, AES and AFM. An evolution of the in-plane anisotropy was observed with the changing thickness of the nonmagnetic TaN interlayer in the FeTaN/TaN/FeTaN sandwiches, such as the easy-hard axis switching and the appearing of biaxial anisotropy. It is ascribed to three possible mechanisms, which are interlayer magnetic coupling, stress, and interface roughness, respectively. Interlayer coupling and stress anisotropies may be the major reasons to cause the easy-hard axis switching in the sandwiches. Whereas, magnetostatic and interface anisotropies may be the major reasons to cause biaxial anisotropy in the sandwiches, in which magnetostatic anisotropy is the dominant one.
Magnetic anisotropy and magnetoresistance of sputtered [(FeTaN)/(TaN)](n) multilayers
H. B. Nie,S. Y. Xu,J. Li,C. K. Ong,J. P. Wang
Physics , 2003,
Abstract: We studied the in-plane magnetic anisotropy of rf (radio frequency) sputtered [(FeTaN)/(TaN)](n) multilayers synthesized on Si substrates. In the multilayers where n=5, the FeTaN thickness is fixed at 30 nm and the thickness of TaN, t(TaN), is varied from 0 to 6.0 nm, we observed a clear trend that, with increasing t(TaN), the values of coercivity, grain size, and amplitude of maximum magnetoresistance (MR) of the samples all decrease first and then increase after reaching a minimum when t(TaN) is around 2.0-4.0 nm. This trend is also associated with an evolution of in-plane magnetic anisotropy, where the multilayers change from uniaxial anisotropy to biaxial at t(TaN) around 4.0 nm and above. We attribute the phenomena to the interlayer coupling effect of FeTaN films as a function of the coupling layer (TaN) thickness, rather than to the thickness dependence observed in single-layered FeTaN films, where the direction of easy axis switches 90degrees when the film is thicker than 300 nm. The in-plane anisotropy of the [(FeTaN)/(TaN)](n) multilayers also shows signs of oscillation when the number of coupling layers varies. The MR effects observed are mainly due to anisotropy MR (AMR), while the grain size and exchange coupling may also contribute to the change of maximum MR ratios in the multilayers with changing t(TaN).
Low Temperature Thermodynamic Study of the Stable and Metastable Phases of Silver
LOW TEMPERATURE THERMODYNAMIC STUDY OF THE STABLE AND METASTABLE PHASES OF SILVER

XB Li,YQ Xie,YZ Nie,HJ Peng,
X.B.
,Li,Y.Q.,Xie,Y.Z.,Nie,H.J.,Peng

金属学报(英文版) , 2007,
Abstract: The low temperature thermodynamics of the stable phase of silver was assessed by the polynomial model and Debye model from the experimental data available in the literature. By means of the constrained non-linear least squares curve fitting arithmetic, two sets of parameter values were determined. The expression of the thermodynamic functions cp(T) and G(T)-H (298.15K) at 0-298.15K were presented. Only the low temperature thermodynamics of the metastable phase of silver can be extrapolated by the Debye model. The expression of the thermodynamic functions cp(T) at 0-298.15K was presented.
Giant Magnetoimpedance of Glass-Covered Amorphous Microwires of Co-Mn-Si-B and Co-Si-B
H. B. Nie,X. X. Zhang,A. B. Pakhomov,Z. Xie,X. Yan,A. Zhukov,M. Vazquez
Physics , 2003,
Abstract: A study of magnetic hysteresis and Giant magnetoimpedance (GMI) in amorphous glass covered Co-Si-B and Co-Mn-Si-B wires is presented. The wires, about 10 microns in diameter, were obtained by glass-coated melt spinning technique. Samples with positive magnetostriction (MS) have a rectangular bistable hysteresis loop. A smooth hysteresis loop is observed for wires with nearly zero MS. When MS is negative, almost no hysteresis is observed. The GMI was measured in the frequency range between 20 Hz and 30 MHz. The shapes of the impedance versus field curves are qualitatively similar to each other for both positive and zero MS samples. Impedance is maximum at zero field, and decreases sharply in the range 10-20 Oe. For the negative MS wires, when the driving current is small, the impedance is maximum at a finite external field. The position of the maximum approaches zero with increasing current. The contributions of the moment rotation and domain wall motion in the three cases are discussed.
Macroscopic Quantum Coherence in Small Antiferromagnetic Particle and the Quantum Interference Effects
Y. -H. Nie,Y. -B. Zhang,J. -Q. Liang,H. J. W. Mueller-Kirsten,F. -C. Pu
Physics , 1999, DOI: 10.1016/S0921-4526(99)00161-1
Abstract: Starting from the Hamiltonian operator of the noncompensated two-sublattice model of a small antiferromagnetic particle, we derive the effective Lagrangian of a biaxial antiferromagnetic particle in an external magnetic field with the help of spin-coherent-state path integrals. Two unequal level-shifts induced by tunneling through two types of barriers are obtained using the instanton method. The energy spectrum is found from Bloch theory regarding the periodic potential as a superlattice. The external magnetic field indeed removes Kramers' degeneracy, however a new quenching of the energy splitting depending on the applied magnetic field is observed for both integer and half-integer spins due to the quantum interference between transitions through two types of barriers.
RECOVERY OF CADMIUM AND NICKEL FROM SCRAP Ni-Cd BATTERIES
JXZhu,BYu,JHLi,
J.X. Zhu
,B. Yu,J.H. Li and Y.F. Nie

金属学报(英文版) , 2001,
Abstract: Several typical methods for the recovery of Ni-Cd batteries are described in detail. Based on the comparing of hydrometallurgical and pyrometallurgical processes, the latter was selected as the suitable method for recycling Ni-Cd batteries in China.
In-Plane Magnetic Anisotropy In RF Sputtered Fe-N Thin Films
H. B. Nie,S. Y. Xu,C. K. Ong,Q. Zhan,D. X. Li,J. P. Wang
Physics , 2003, DOI: 10.1016/S0040-6090(03)00833-2
Abstract: We have fabricated Fe(N) thin films with varied N2 partial pressure and studied the microstructure, morphology, magnetic properties and resistivity by using X-ray diffraction, atomic force microscopy, transmission electron microscopy, vibrating-sample magnetometer and angle-resolved M-H hysteresis Loop tracer and standard four-point probe method. In the presence of low N2 partial pressure, Fe(N) films showed a basic bcc a-Fe structure with a preferred (110) texture. A variation of in-plane magnetic anisotropy of the Fe(N) films was observed with the changing of N component. The evolution of in-plane anisotropy in the films was attributed to the directional order mechanism. Nitrogen atoms play an important role in refining the a-Fe grains and inducing uniaxial anisotropy.
A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM
XB Li,YQ Xie,YZ Nie,HJ Peng,HJ Tao,FX Yu,
X.B.
,Li,Y.Q.,Xie,Y.Z.,Nie,H.J.,Peng,H.J.,Tao,F.X.,Yu

金属学报(英文版) , 2007,
Abstract: On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is ec2.9907 .(sc0.4980 dc2.4927) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.
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