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Wang X.C.,Tianjin University of Technology | Mi W.B.,China Institute of Advanced Materials Physics | Kuang D.F.,China Institute of Technology
Applied Surface Science | Year: 2010

Microstructure, magnetic and optical properties of polycrystalline Fe-doped ZnO films fabricated by cosputtering with different Fe atomic fractions (xFe) have been examined systematically. Fe addition could affect the growth of ZnO grains and surface morphology of the films. As xFe is larger than 7.0%, ZnFe2O4 grains appear in the films. All the films are ferromagnetic. The ferromagnetism comes from the ferromagnetic interaction activated by defects between the Fe ions that replace Zn ions. The average moment per Fe ion reaches a maximum value of 1.61 μB at xFe = 4.8%. With further increase in xFe, the average moment per Fe ion decreases because the antiferromagnetic energy is lower than the ferromagnetic one due to the reduced distance between the adjacent Fe ions. The optical band gap value decreases from 3.245 to 3.010 eV as xFe increases from 0% to 10%. Photoluminescence spectra analyses indicate that many defects that affect the optical and magnetic properties exist in the films. © 2009 Elsevier B.V. All rights reserved.

Li S.,China Institute of Advanced Materials Physics | Zhang J.,China Institute of Advanced Materials Physics | Wu P.,China Institute of Advanced Materials Physics
Journal of Crystal Growth | Year: 2010

We extend Galenko's nonequilibrium kinetic model of planar interface migration during solidification to non-dilute solution with non-straight liquidus and solidus curves. Using this more complex thermodynamic model for silicon-arsenic we show that the model with significant solute drag is consistent with the available experimental data for Si-9at%As alloy. Comparison with the typical kinetic models shows that the present model provides a better description of the data and the linear phase boundary assumption may lead to a relatively large deviation from reality. © 2010 Elsevier B.V. All rights reserved.

Yang Z.,China Institute of Advanced Materials Physics | Zhou W.,China Institute of Advanced Materials Physics | Wu P.,China Institute of Advanced Materials Physics
Materials Science and Engineering A | Year: 2014

Microstructure and mechanical properties including tensile strength as well as creep resistance of Ni-Coated Carbon Nanotube reinforced Sn-Ag-Cu solders were investigated in this study. Addition of 0.05. wt% Ni-Coated Carbon Nanotubes improved the ultimate tensile strength of composite solder slabs (up to 9.80%) and joints (up to 15.95%). The increase in strengthening effect of solder joints can be attributed to the consumption of Ni by interface reaction during soldering. Nanoindentation results revealed that the creep behaviors of composite solders were improved significantly as compared to that of the unreinforced solder alloy. Finite-element modeling showed that load transfer by Carbon Nanotubes took effect but was far smaller than the effect of Ni-Coated Carbon Nanotubes served as obstacles preventing dislocations gliding. © 2013 Elsevier B.V.

Wang J.,Tianjin University | Jia G.,Tianjin University | Mu X.,Tianjin University | Liu C.,Tianjin University | Liu C.,China Institute of Advanced Materials Physics
Applied Physics Letters | Year: 2013

Ag nanoparticles were fabricated in silica by Xe ion irradiation and subsequent Ag ion implantation, which distributed in a depth range from 4.8 to 14.3 nm, rather than dispersed from surface to a depth of 24.7 nm when no irradiation was made in advance. In addition, the suppression of Ag implants sputtering loss was also evidenced by a greatly increased Ag content in the prepared sample. These results are mainly due to the defect-enhanced in-beam particle growth. Further, formation of polycrystalline Ag nanoparticles was revealed, whose effect on optical absorption was discussed according to the electron mean-free-path mode. © 2013 American Institute of Physics.

Yang X.,China Institute of Advanced Materials Physics | Kozhevnikov I.V.,RAS Shubnikov Institute of Crystallography | Huang Q.,China Institute of Advanced Materials Physics | Wang Z.,China Institute of Advanced Materials Physics
Journal of the Optical Society of America B: Optical Physics | Year: 2015

A universal analytical theory of soft x-ray multilayer gratings operating in the single-order regime is developed here. The single-order regime, in which an incident wave excites only the diffracted wave, is characterized by the maximum possible diffraction efficiency tending to the reflectivity of a conventional multilayer mirror. The theory is applied to analysis of different multilayer gratings, including lamella multilayer gratings, sliced multilayer gratings, blazed multilayer gratings, and blazed lamella multilayer gratings. A simple analytical formula that describes the diffraction efficiency of an arbitrary multilayer grating as a function of the wavelength and the incidence angle is deduced. Expressions for the peak value of the diffraction efficiency and the generalized Bragg condition corresponding to the maximum efficiency are obtained. The high accuracy of the deduced analytical expressions is justified by comparison with rigorous numerical calculations. Comparative analysis of different types of gratings is performed. The advantages and disadvantages of different gratings in practical applications are discussed. © 2015 Optical Society of America.

Lin J.,China Institute of Advanced Materials Physics | Sha J.,China Institute of Advanced Materials Physics | Wang Z.,Broadcom Corporation | Li L.,China Institute of Advanced Materials Physics
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2010

This paper addresses decoder design for nonbinary quasicyclic low-density parity-check (QC-LDPC) codes. First, a novel decoding algorithm is proposed to eliminate the multiplications over Galois field for check node processing. Then, a partially parallel architecture for check node processing units and an optimized architecture for variable node processing units are developed based on the new decoding algorithm. Thereafter, an efficient decoder structure dedicated to a promising class of high-performance nonbinary QC-LDPC codes is presented for the first time. Moreover, an ASIC implementation for a (620, 310) nonbinary QC-LDPC code decoder over GF(32) is designed to demonstrate the efficiency of the presented techniques. © 2010 IEEE.

Zhang Q.,PSE Division KAUST Thuwal 23955 6900 Kingdom of Saudi Arabia | Yang S.A.,Singapore University of Technology and Design | Mi W.,China Institute of Advanced Materials Physics | Cheng Y.,Nanjing University of Technology | Schwingenschlogl U.,PSE Division KAUST Thuwal 23955 6900 Kingdom of Saudi Arabia
Advanced Materials | Year: 2015

The electronic properties of monolayer MoTe2 on top of EuO(111) are studied by first-principles calculations. Strong spin polarization is induced in MoTe2, which results in a large valley polarization. In a longitudinal electric field this will result in a valley and spin-polarized charge Hall effect. The direction of the Hall current as well as the valley and spin polarizations can be tuned by an external magnetic field. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Li S.,China Institute of Advanced Materials Physics | Zhang J.,China Institute of Advanced Materials Physics | Wu P.,China Institute of Advanced Materials Physics
Scripta Materialia | Year: 2010

A generalized solute drag model for binary alloy solidification with a planar phase interface was proposed as an extension of Hillert-Sundman model. Using a new thermodynamic parameter set of the Si-As system, the present model can, with the introduction of three new adjustable parameters, fit the available experimental data of Si-9 at.% As alloy. In addition, non-solute drag models with the new set of thermodynamic parameters cannot reproduce the experimental data. © 2010 Acta Materialia Inc.

Wang J.,Tianjin University | Zhang L.,Tianjin University | Zhang X.,Tianjin University | Shen Y.,Tianjin University | And 2 more authors.
Journal of Alloys and Compounds | Year: 2013

CuZn alloy nanoparticles (NPs) embedded in amorphous SiO2 were fabricated by means of sequential implantation of 45 keV Cu and Zn ions at the same fluence of 1 × 1017 cm-2 together with subsequent annealing at 500 °C in nitrogen ambient. Such binary alloy NPs presented an intense surface plasmon resonance (SPR) absorption peak at about 515 nm. After 600 °C annealing, the already formed alloy NPs were found to be decomposed. The Zn atoms separated from the alloy NPs diffused toward the surface of sample, while the Cu atoms nearly stayed at original sites to form Cu NPs, inducing a SPR absorption signal much stronger than that detected in the Cu singly implanted sample after the same annealing. Moreover, a weak photoluminescence band around 558 nm was revealed in the sequentially implanted sample after annealing. The possible luminescent mechanism was discussed. © 2012 Elsevier B.V. All rights reserved.

Yao D.,China Institute of Advanced Materials Physics | Ge S.,Lanzhou University | Zhou X.,Jiujiang University
Physica B: Condensed Matter | Year: 2010

A series of (Fe65Co35)x(SiO2)(1-x) nano-granular films with different volume fraction x are fabricated by magnetron co-sputtering technique. The structure, magnetic and high frequency properties are investigated systematically by using X-ray diffraction, transmission electronic microscopy, vibrating sample magnetometer, resistivity and complex permeability measurements. Study results indicate that the films consist of Fe65Co35 magnetic metal particles uniformly embedded in an insulating SiO2 matrix. (Fe65Co35)x(SiO2)(1-x) films exhibit large magnetic anisotropy field Hk and excellent soft magnetic properties in a wide x range from 0.80 to 0.52 with coercivity Hc smaller than 18 Oe. A minimum Hc value of 7.8 Oe is obtained for the sample with x=0.60 whose electrical resistivity ρ reaches 2220 μ Ω cm and the magnetic anisotropy field Hk is as high as 185 Oe. Especially, for the result of complex permeability measurement of the samples, very high ferromagnetic resonance (FMR) frequency is obtained. For the typical sample with x=0.60, the FMR frequency reaches 4.9 GHz, implying a very high cut-off frequency for high frequency applications, and the real part μ′ of its complex permeability exceeds 60 below 3.8 GHz while the imaginary part μ″ is very small until f>2.0 GHz. These good high frequency properties imply that (Fe65Co35)x(SiO2)(1-x) granular films are promising for applications in high frequency range. The good soft magnetic properties are ascribed to the exchange coupling among magnetic particles, which is discussed in this paper. © 2009 Elsevier B.V. All rights reserved.

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