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Characteristic Investigation of nano-crystal Hydrogen Storage Alloys

Journal of Rare Earths 2004年第Z1期22卷 232-234页

作者： Xiao Fangming Huang Lili Tang Renheng Lu Qiyun Peng Neng Wang Ying Rare Earth Materials Research Center Guangzhou Research Institute of Nonferrous Metals Guangzhou 510651 China

A Ml (NiCoMnA1)5 hydrogen storage alloys was prepared by double-roller rapid *** microstructure, electrochemically and kinetic characteristic were studied.A uniform crystal phase with CaCu5 structure could be detected by XRD analyses, whose average grain size is 30 ~ 50 nm and the ratio of c/a of nano-crystal hydrogen storage alloy is *** hydrogen absorption/desertion p - C isotherms of alloy show that its fiat-performance is perfect and the magnetic stagnant effect is very *** simulate cell is used for electrochemical *** is 10C, the capacity decreasing rate via the 450 cycles at 7C is less than 20%.

关键词： nano-crystal hydrogen storage alloys electrochemically characteristic

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Determination of the Nucleation Region Location of Si nano-crystal Grains Prepared by Pulsed Laser Ablation through Changing Position of Substrates

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Journal of Surface Engineered Materials and Advanced Technology 2013年第2期3卷 133-137页

作者： Zechao Deng Qingshan Luo Ziqiang Hu Xiaolong Zhang Xuecheng Ding Lizhi Chu Yinglong Wang College of Physics Science and Technology Hebei University. Key Laboratory of Photo-Electronics Information Materials of Hebei Province Baoding China Key Laboratory of Earthquake Geodesy Institute of Seismology CEA Wuhan China.

To determine the nucleation region location of Si nano-crystal grains, pulsed laser ablation of Si target is performed in Ar gas of 10 Pa at room temperature with laser fluence of 4 J/cm2, the substrates are located horizontal under ablation spot with different vertical distance. Characteristics of deposited grains are described by scanning electron microscopy, Raman scattering and X-ray diffraction spectra, the results indicate that deposition position on substrates in a certain range is relative to target surface, which changes according to different vertical distance of substrates to ablation spot. Grain size increased?at first and then decreased with addition of lateral distances to target in the range, but the integral distribution rule was independent of position of substrates. Combining with hydrodynamics model, nucleation division model, thermokinetic equation and flat parabolic motion, spatial nucleation region location of grains is obtained through numerical calculations, which is 2.7 mm-43.2 mm to target surface along the plume axis.

关键词： Nucleation Region Location Si nano-crystal Grains Pulsed Laser Ablation

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Assessment of physical properties of nano-crystal hydroxyapatite scaffold coated with poly-hydroxybutyrate for bone tissue engineering

Assessment of physical properties of nano-crystal hydroxyapa...

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2011 World Congress on Engineering and Technology(CET 2011)

作者： Mohammad reza Foroughi Reza Ebrahimi-Kahrizsangi Saeed Karbasi Mohammad reza Monshi Islamic Azad University Najafabad branchDepartment of Materials engineering Isfahan Medical Physics and Biomedical Engineering Group School of MedicineIsfahan University of Medical Science Isfahan

In this paper,firstly,hydroxyapatite （HAp） powder has been made out of bovine bone by thermal analysis at temperature of 900°C and then HAp porous of 40,50 and 60%wt produced by polyurethane sponge replication *** order to lift scaffolds` mechanical properties,they have been coated with poly-hydroxybutyrate （P3HB）.In terms of phased studies,morphology and specifying agent groups,it has been used of characterization devices as XRD,SEM and FT-IR,*** Data obtained from XRD and FT-IR,the best temperature to produce HAp powder was temperature of 900°C which is voided of *** of the study presented a scaffold with 90% of porous level in size numbers of 100 and 400μ*** the porosity and morphology of scaffold have indicated,the most excellent scaffold was of 50%wt of HAp which can be utilized in bone tissue engineering.

关键词： Hydroxyapatite (HAp) Poly-hydroxybutyrate (P3HB) Scaffold nano-crystal Bone Tissue Engineering Physical properties

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A novel synthesis method and up-conversion properties of hexagonal-phase NaYF_4:Er nano-crystals

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Journal of Rare Earths 2013年第3期31卷 267-270页

作者：罗显佳 Ryosuke Yuminami Takeaki Sakurai Katsuhiro Akimoto Institute of Applied Physics University of Tsukuba1-1-1 TennodaiTsukubaIbaraki 305-8573Japan

A novel synthesis method for hexagonal （]3）ophase NaYF4：Er nano-crystals （NCs） which showed up-conversion （UC） from infrared to visible spectral region was developed. The NaYF4：Er NCs were synthesized in oleie acid （OA） and 1-0ctadeeene （ODE） with Y2（COa）3＇xH20, Er2（COa）3xH20, Na2CO3 and NH4F as precursors. This proposed method was simple and less toxic compared with generally used method so far. The XRD results showed that the molar ratio of OA/ODE and the temperature were key factors for phase control ofNaYF4：Er NCs. The UC emission spectra were obtained with the emission wavelength at about 980 nm （4111/2--4115/2）, 800 nm （41912--415/2）, 660 nm （4F912--4115/2） and 540 nm （453/2----4115/2） from Er3＋ ions, by excitation wavelength of 1550 nm. The slope values, n, in the pump-power dependence, showed that the emission at 980 and 800 um were generated by 2-step UC and at 660 nm and 540 um were 3-step UC. The optical process for the UC excitation was discussed.

关键词： rare earths luminescence up-conversion nano-crystal NaYF4

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Modified Scherrer Equation to Estimate More Accurately nano-crystallite Size Using XRD

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World Journal of nano Science and Engineering 2012年第3期2卷 154-160页

作者： Ahmad Monshi Mohammad Reza Foroughi Mohammad Reza Monshi Department of Materials Engineering Najafabad branch Islamic Azad University Isfahan Iran

Scherrer Equation, L=Kλ/β.cosθ, was developed in 1918, to calculate the nano crystallite size (L) by XRD radiation of wavelength λ (nm) from measuring full width at half maximum of peaks (β) in radian located at any 2θ in the pattern. Shape factor of K can be 0.62 - 2.08 and is usually taken as about 0.89. But, if all of the peaks of a pattern are going to give a similar value of L, then β.cosθ must be identical. This means that for a typical 5nm crystallite size and λ Cukα1 = 0.15405 nm the peak at 2θ = 170° must be more than ten times wide with respect to the peak at 2θ = 10°, which is never observed. The purpose of modified Scherrer equation given in this paper is to provide a new approach to the kind of using Scherrer equation, so that a least squares technique can be applied to minimize the sources of errors. Modified Scherrer equation plots lnβ against ln(1/cosθ) and obtains the intercept of a least squares line regression, ln=Kλ/L, from which a single value of L is obtained through all of the available peaks. This novel technique is used for a natural Hydroxyapatite (HA) of bovine bone fired at 600°C, 700°C, 900°C and 1100°C from which nano crystallite sizes of 22.8, 35.5, 37.3 and 38.1 nm were respectively obtained and 900°C was selected for biomaterials purposes. These results show that modified Scherrer equation method is promising in nano materials applications and can distinguish between 37.3 and 38.1 nm by using the data from all of the available peaks.

关键词： X-Ray Diffraction nano-crystal Scherrer Equation Hydroxyapatite

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Precipitation behavior and grain refinement of burnishing Al-Zn-Mg alloy

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Progress in Natural Science:Materials International 2018年第1期28卷 54-59页

作者： Ce Pang Hongyun Luo Zheng Zhang Yue Ma Key Laboratory of Aerospace Materials and Performance School of Materials Science and Engineering Beihang University

Burnishing is a unique strengthening approach to improve the strength of surface layer and remains the ductility of the interior of metallic materials. In this work, burnishing treatment was employed to improve the surface microstructure of naturally aged Al-Zn-Mg alloys after solid solution. Transmission electron microscopy, highresolution transmission electron microscopy, X-ray diffraction and nano-indentation were used to characterize the effects of the burnishing on the microstructures of surface layer and Guinier-Preston(GP) zones. It was indicated that GP zones uniformly distributed and dispersed in the matrix before burnishing, and the amount of GP zones decreased dramatically after burnishing processing. Additionally, the grains in the surficial layer were refined into nano-crystals with an average grain size of 78 nm. Burnishing treatment not only led to formation of large number of dislocation substructures in the sub-surface and near-matrix surface, but also promoted the precipitation of metastable η' phase at grain boundaries. The synergistic effects of the grain refinement, dislocation multiplication and the precipitation of η' phase strengthen the burnished layer of Al-Zn-Mg alloy.

关键词： Al-Zn-Mg alloy Burnishing nano-crystal Precipitation Grain refinement

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SYNTHESIS OF Ni-Mo ALLOYS BY MECHANICAL ALLOYING

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Acta Metallurgica Sinica(English Letters) 1993年第12期6卷 437-441页

作者： LIANG Guoxian WANG Erde HUO Wencan Harbin Institute of Technology,Harbin,China Post Box 435,Harbin Institute of Technology,Harbin 150006,China Harbin Inst of Technology Harbin China

Ni_(100-x)Mo_x(x=20,30,38)alloys have been synthesized by mechanical *** structure evolution of powders in mechanical alloying process has been monitored by X-ray diffraction,scanning electron microscopy and transmission electron microscopy *** results show that the Ni_(62)Mo_(38)sample becomes partially amorphous after high energy ball milling,while the Ni_(80)Mo_(20)and Ni_(70)Mo_(30)become non-equilibrium nanocrystals.

关键词： mechanical alloying Ni-Mo alloy amorphization nano-crystal

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Study on the Microstructure of Hot-Pressed and Hot-Deformed Nd-Fe-B Magnets

Study on the Microstructure of Hot-Pressed and Hot-Deformed ...

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加速功能材料自主创新，促进西部战略性新兴产业发展——2...

作者： Yilong MA,Jiandong XUE,Dengming CHEN,Anruo ZHOU,Jianchun SUN College of Metallurgy and Materials Engineering Chongqing University of Science and Technology,Chongqing,China

Anisotropic nano-crystalline Nd-Fe-B magnets were prepared by applying the MQ-C melt-spun powders and the technique of hot-pressing(HP)and hot-deformation(HD).The change of magnetic properties and microstructure was studied in *** results showed that:the HD magnets had a good c-axis texture and the magnetic properties increased largely;the MQ-C powder stacked well along the pressure direction during HP,and the powder particles elongated perpendicular to the pressure direction during HD;in HD magnets,there were a lot of unoriented and coarse grains,which had a higher Nd content than the plate-like grains.

关键词： Nd-Fe-B nano-crystal hot-deformation microstructure

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