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Numerical simulations and experimental investigations on transverse effects of two-wave mixing in a photovoltaic photorefractive crystal

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science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 856-863页

作者： CAI Xin1,2,LIU JinSong1 & WANG ShengLie1 1 wuhan National Laboratory for Optoelectronics,school of Optoelectronic science and engineering,Huazhong university of science and technology,wuhan 430074,china 2 school of science,wuhan university of technology,wuhan 43.070,china 1. wuhan National Laboratory for Optoelectronics School of Optoelectronic Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China2. School of Science Wuhan University of Technology Wuhan 430070 China

The transverse effects of two Gauss waves mixing in a photovoltaic photorefractive crystal,i.e.,the dynamical evolutions of signal beam with different parameters,are traced numerically and *** the one-dimensional numerical simulations and two-dimensional experimental investigations show that the self-focusing effect of signal beam becomes more obvious as the intensity of pump beam and the angle between the signal and pump beams *** accordance with these results,the state of two Gaussian waves mixing is controllable.

关键词： numerical simulation experimental investigation two-wave mixing transverse effects Gaussian distribution

Ferroelectric properties of Bi_(3.4)Ho_(0.6)Ti_3O_(12) thin films prepared by sol-gel method

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science china(Technological sciences) 2008年第9期51卷 1439-1444页

作者： FU ChengJu1, HUANG ZhiXiong1, LI Jie2 & GUO DongYun3 1 school of materials science and technology, wuhan university of technology, wuhan 43.070, china 2 school of Mechanical engineering, Chongqing university of science and technology, Chongqing 400050, china 3 Department of Physics, wuhan university, wuhan 430072, china school of materials science and technology Wuhan University of Technology Wuhan 430070 China school of Mechanical engineering Chongqing University of Science and Technology Chongqing 400050 China Department of Physics Wuhan University Wuhan 430072 China

We have prepared the Ho-substituted bismuth titanate (Bi3.4Ho0.6Ti3O12, BHT) thin films on Pt/Ti/SiO2/Si substrates using sol-gel method. The crystal structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The BHT film shows a single phase of Bi-layered Aurivillius structure and dense microstructure. The 2Pr and 2Ec of the 600-nm-thick BHT film were 38.4 μC/cm2 and 376.1 kV/cm, respectively at applied electric field 500 kV/cm. The dielectric constant and dielectric loss are about 310 and 0.015 at a frequency of 1 MHz, respectively. The Pr value decreased to 93% of its pre-fatigue values after 4.46×109 switching cycles at 1 MHz frenquency, and the BHT film shows good in-sulating behavior according to the test of leakage current.

关键词： Bi3.4Ho0.6Ti3O12 thin film sol-gel method ferroelectric property fatigue dielectric constant

Early Age Compressive Strength of Pastes by Electrical Resistivity Method and Maturity Method

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Journal of wuhan university of technology(materials science) 2011年第5期26卷 983-989页

作者：肖莲珍 school of materials science and engineering Wuhan Institute of Technology

The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity *** experiments were carried out on the cement pastes with different water-cement ratios at different curing *** results show that the application of the maturity method has limitation to obtain the *** is found that both of the compressive strength and the electrical resistivity follow hyperbolic trend for all the *** hyperbolic equation of each mix is obtained to estimate the ultimate resistivity value which can probably be *** relationship between electrical resistivity and compressive strength of the cement pastes is established based on the test results and interpreted by the empirical Archie equation and a strength-porosity *** relationship between the electrical resistivity after temperature correction and the compressive strength was linear and independent of curing temperature and water-cement ratio.

关键词： electrical resistivity cement hydration compressive strength maturity method

Development of Mathematical Model on Preparation of Functionally Graded Material by Co-sedimentation

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Journal of materials science & technology 2001年第2期17卷 275-277页

作者： Zhongmin YANG, Lianmeng ZHANG and Qiang SHEN Institute of materials science and engineering, wuhan university of technology, wuhan 43.070, china wuhan Univ Technol Inst Mat Sci & Engn Wuhan 430070 Peoples R China

From the process of sedimentation the mathematical relationships among deposition Volume and powder properties as well as sedimentation parameters were deduced. Based on the formula a mathematical model was set up and simulated through the computer. At last the validity of mathematical model was supported by the representative experiment on Ti-Mo system FGM prepared by co-sedimentation.

关键词： Co Mo Development of Mathematical Model on Preparation of Functionally Graded Material by Co-sedimentation

Refinement Role of Electromagnetic Stirring and Calcium in AZ91 Magnesium Alloy

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Journal of wuhan university of technology(materials science Edition) 2008年第2期23卷 194-197页

作者： HAN Hui LIU Shengfa KANG Liugen LIU Linyan (school of materials science and engineering,wuhan university of technology,wuhan 43.070,china) school of materials science and engineering Wuhan University of Technology Wuhan 430070 China

Effects of calcium addition and electromagnetic stirring on the microstructure of AZ91 magnesium alloy and refinement mechanism were *** results show that calcium addition ranging from 0.1wt% to 0.3 wt% does not lead to formation of any new phases but cause the refinement of as- cast ***,combined calcium alloying and electromagnetic stirring significantly decrease the grain size,change the morphologies of theβ-Mg17Al12phases,and reduce their volume *** minimum grain size of AZ91 alloy is obtained in the case of the addition of 0.2 wt%Ca with exciting voltage of 100 *** microstructural refinement is attributed to the increase of the degree of undercooling and nucleation temperature of primaryα-Mg phases on the basis of DTA analysis results.

关键词： AZ91 magnesium alloy electromagnetic stirring calcium microstructural refinement

β-Sialon Produced by Carbon Thermal Nitriding Reaction of Bauxite

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International Journal of Minerals,Metallurgy and materials 2000年第3期14卷 209-213页

作者： Jun Wang, Nan Li, Caicheng Shi, Chengchang Jia ( Material science and engineering school, university of science and technology Beijing, Beijing 100083, china Material science and engineering school, wuhan university of science and technology, wuhan 430 Material science and engineering school University of Science and Technology Beijing Beijing 100083 China Material science and engineering school Wuhan University of Science and Technology Wuhan 430081 China

β-Sialon was produced by carbon thermal nitriding reaction in N_2 gas atmosphere when the mixtures of bauxite and anthracite were put into vertical furnace. According to the mass loss of raw materials and the result of X-ray diffration (XRD) of products, the influences of the process parameters on the compositions and relative contents of products, such as the fixed carbon content, the flow of N2, the soaking time and the temperature, were researched.

关键词： β-Sialon bauxite anthracite carbon thermal nitriding processing parameter vertical furnace

Synthesis of Cr-Al_2O_3 Cermet Selective Surfaces Coated by SnO_2 Thin Film by Air Plasma Spraying

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稀有金属材料与工程 2012年第S1期41卷 272-275页

作者： Zhu Zhenqi,Cheng Xudong,Li Guanglei school of materials science and technology,wuhan university of technology,wuhan 43.070,china wuhan Univ Technol State Key Lab Adv Technol Mat Synth & Proc Sch Mat Sci & Technol Wuhan 430070 Peoples R China

High efficient Cr-Al2O3 cermet selective surfaces coated by sol-gel SnO2 thin film for high-temperature application were synthesized by air plasma spraying(APS),followed further heat and polish *** phase composition and micro morphology of coating samples were characterized by X-ray diffractions(XRD),scanning electron microscope(SEM)and roughmeter *** solar absorptance(α)and thermal emittance(ε)were determined by optical spectrum *** results show that Cr-Al2O3 cermet coating has a high absorptivity nearly *** unfortunately,the emissivity of these coatings is nearly 0.50 because of the big thickness and coarse surface prepared by APS ***,once coated SnO2 thin film,the composite coatings exhibit excellent selective absorbing property of α=0.89 and ε=***,SnO2 thin film plays a significant role in decreasing the emissivity of coatings as antireflection *** furthermore,the optical performance shows that more metal content and smooth surface are favorable for the selective absorbing ***,the coatings have excellent bond strength with stainless steel substrate and thermal shock resistance at high temperature.

关键词： selective surfaces SnO2 thin film air plasma spraying

Effect of Preparation Atmosphere on the Structure and Properties of Vanadium Pentoxide Xerogel Films

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Journal of materials science & technology 2004年第3期20卷 365-367页

作者： Wen CHEN Manzhu KB Qing XU Quanyao ZHU Liqiang MAI Li LI school of materials science and engineering, wuhan university of technology,wuhan 43.070, china Sch. of Mat. Sci. and Eng. Wuhan Univ. of Technol. Wuhan 430070 China

In this article, the vanadium pentoxide sols are synthesized by two different routes (melted and quenched in oxygenatmosphere or in air). The structure and properties of the vanadium pentoxide xerogel films are characterized byXRD, ESR, cyclic voltammograms curves and UV-visible transmittance analysis. The results show that the sampleprepared in oxygen has poorer crystallization. lower content of V^(4+) ions and higher Li^+ insertion capacity comparedwith that prepared in air.

关键词： Preparation atmosphere V_2O_5 Structure Properties

The Role of Calcium in Microstructural Refinement of AZ91 Magnesium Alloy

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Journal of wuhan university of technology(materials science) 2006年第4期21卷 45-47页

作者：刘生发 school of materials science and engineering Wuhan University of Technology Wuhan 430070China

The effect of calcium addition on the microstructures of AZ91 magnesium alloy was investigated. It was found that a small amount of calcium in AZ91 allay produced a large decrease in the α- Mg grain size and the dispersed fine β-Mgt7 Alt2 phases. In addition, some Al4Ca particles were found to exist in the AZ91 alloy containing 0.5wt% Ca. EDS analysis and water-quenched technique revealed that the grain-refining mechanism of calcium for the AZ91 alloys was mainly attributed to the role of restricting growth of calcium in the primary α-Mg crystals.

关键词： AZ91 magnesium alloy calcium microstructural refinement