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Effect of rare earth samarium addition on the kinetics of precipitation in Al-Cu-Mn casting alloy

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 155-161页

作者： Zhong-wei Chen Ming-jun Tang Kai Zhao State Key Laboratory of Solidification Processing Northwestern Polytechnical University

The mechanical properties of Al-Cu-Mn casting alloy mainly depend on the morphology, distribution, size, and number ofθ′（Al2Cu） precipitates. In this study, we have analyzed the effect of rare earth samarium （Sm） addition on the kinetics of precipitation in the Al-Cu-Mn casting alloy by using differential scanning calorimetry （DSC） and high-resolution transmission electron microscopy. Thermal ef-fect peaks that are attributed to the formation and the dissolution of Guinier-Preston （GP） zone andθ′phase were identified from the DSC curves. The activation energy ofθ′formation was calculated by using both the Kissinger method and the analytical model, and the corre-sponding results were compared. Results suggest that the activation energy ofθ′formation in Al-Cu-Mn alloy is dramatically higher than that in Al-Cu-Mn-Sm alloy. Accordingly, it is concluded that the addition of rare earth Sm decreases the activation energy ofθ′formation and promotes the formation ofθ′precipitates.

关键词： aluminum copper alloys rare earth additions samarium precipitation kinetics

Influence of Nd and Y additions on the corrosion behaviour of extruded Mg-Zn-Zr alloys

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International Journal of Minerals,Metallurgy and Materials 2011年第2期18卷 203-209页

作者： Jian-wei Chang Jun Duo Ya-zhen Xiang Hai-yan Yang Wen-jiang Ding Ying-hong Peng School of Materials Science and Engineering Shanghai Jiaotong University Shanghai 200240 China School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200240 China School of Mechanical Engineering Qinghai University Xining 810086 China School of Environmental Science and Engineering Shanghai Jiaotong University Shanghai 200240 China

To improve the corrosion resistance of wrought magnesium alloys through rare earth （RE） additions, the corrosion behaviour of Mg-5Zn-0.3Zr-xNd （x=0, 1, and 2; wt%） and Mg-5Zn-0.3Zr-2Nd-yY （y=0.5 and 1; wt%） alloys in a 5wt% NaCl solution was investigated using immersion test and electrochemical measurements. The results of immersion test show that Mg-5Zn-0.3Zr-2Nd alloy exhibits the best corrosion resistance among the tested alloys. Electrochemical measurements show that secondary phases in RE-containing Mg-5Zn-0.3Zr alloys behave as less noble cathodes in micro-galvanic corrosion and suppress the cathodic process. The additions of Nd and Y into Mg-5Zn-0.3Zr alloy also improve the compactness of the corrosion product film and are beneficial to the corrosion resistance.

关键词： magnesium alloys corrosion resistance rare earth additions electrochemical properties neodymium yttrium

Er^(3+)-doped phosphor-tellurite glass for broadband short-length Er^(3+)-doped fiber amplifier

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Chinese Optics Letters 2008年第4期6卷 276-278页

作者：赵士龙郑飞徐时清王焕平王宝玲 College of Materials Science and Engineering China Jiliang University Hangzhou 310018

Er^3＋-doped phosphor-tellurite glass for broadband short-length Er^3＋-doped fiber amplifier （EDFA） is fabricated and characterized. The differential value （AT） of onset crystalline temperature （Tx） and glass transition temperature （Tg） is 206 ℃. The stimulated emission cross section of Er^3＋ is calculated from absorption spectrum by McCumber theory and is 0.87 × 10 ^-20 cm^2 at 1532 nm. A broad 1.5-μm fluorescence spectrum with 54-nm full-width at half maximum （FWHM） is demonstrated. Especially, the maximum phonon energy of undoped phosphor-tellurite glass is 1100 cm^- 1, which restricts the upconversion luminescence. It is possible to pump efficiently at 980 nm. These results indicate Er^3＋-doped phosphor-tellurite glass is suitable for fabricating broadband short-length EDFA.

关键词： Absorption spectra Electron transitions Erbium doped fiber amplifiers Fluorescence Full width at half maximum Glass transition rare earth additions Stimulated emission

High power pulse amplification of ytterbium-doped double-clad fiber amplifier

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Chinese Optics Letters 2007年第11期5卷 624-627页

作者：常丽萍范薇陈嘉琳王利陈柏林尊琪 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800

By solving a set of time-dependent equations, the characteristics of the ytterbium-doped double-clad fiber amplifier are presented. Besides the steady state in the fiber of the upper-state population, pump power and amplified spontaneous emission without the input signal, the dynamic characteristics of the high power Gaussian pulse amplification like the evolution of pulse waveform distortion, upper-state population distribution and stored energy and pulse energy of the amplifier under the forward and backward pump, are simulated. The relations between the output pulse energy of the amplifier and the different input pulse peak power or pump power are also discussed. The models and results can provide important guide for the design and optimization of the high power pulse amplification.

关键词： Amplification Distortion (waves) Doping (additives) rare earth additions Spontaneous emission Ytterbium

Effect of charge compensation on emission spectrum of Ca_2SiO_4:Dy^(3+) phosphor

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Chinese Optics Letters 2008年第4期6卷 274-275页

作者：李盼来张子才张坤杨志平王志军郭庆林 College of Physics Science and Technology Hebei University Baoding 071002 Industrial and Commercial College Hebei University Baoding 071002

The Ca2SiO4：Dy^3＋ phosphor was synthesized by the high temperature solid-state reaction method in air. The emission spectrum of Ca2SiO4：Dy^3＋ phosphor shows several bands at 486, 575, and 665 nm under the 365-nm excitation. The effects of Li^＋, Na^＋, and K^＋ on the emission spectrum of Ca2SiO4：Dy^3＋ phosphor were studied. The results show that the emission spectrum intensity is greatly influenced by Li^＋, Na^＋, and K^＋. The charge compensation concentration corresponding to the maximum emission intensity is different with different charge compensations.

关键词： Calcium compounds Dysprosium Emission spectroscopy rare earth additions Solid state reactions

Acousto-optic Q-switched cladding-pumped ytterbium-doped fiber laser

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Chinese Optics Letters 2007年第7期5卷 415-417页

作者：彭博柳强巩马理闫平 Center for Photonics and Electronics State Key Laboratory of Tribology Department of Precision InstrumentsTsinghua UniversityBeijing 100084

A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 μm is used to increase the laser gain volume and the pulse energy efficiently. The average power in excess of 9 W is obtained at the repetition rate of 20 kHz with 66% slope efficiency. The pulse width is 198 ns with no evident amplified spontaneous emission between pulses, thus the pulse energy and peak power are 465 μJ and 2.36 kW, respectively.

关键词： Multimode fibers Q switched lasers rare earth additions Spontaneous emission Ytterbium

Status of Applications of rare earth Metals to Precision Alloys

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rare Metals 1990年第1期10卷 69-72页

作者： Zhong, Qiunuan Tianjin Metallurgical Material Inst China

rare earth resources in China are the most abundant, the production capability ranks second in the world. The first generation of rare earth-transition group permanent magnet alloy RECo5 developed in 1970's started using rare earths as substantial components. Because of the need of product diversity and to utilize rich resources of mixed rare earth metals, researchers are working on substitution of expensive elemental rare earth metals with cheaper cerium or mixed rare earths (rich in cerium, lanthanum or neodymium) to make lower cost permanent - magnet such as CeCo5. Ce[CoCuFe]5. etc.

关键词： Magnetic Materials rare earth additions Magnets Crystalline rare earth Elements Peoples Republic of China

Optical spectra and local structure of Eu^(3+) ions doped in Nb_2O_5-La_2O_3-B_2O_3-BaO glasses

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Chinese Optics Letters 2006年第8期4卷 476-479页

作者：夏海平章践立王金浩张约品 Laboratory of Photo-Electronic Materials Ningbo University

The xNb2O5-（15-x）La2O3-40B2O3-45BaO （x = 5, 7.5, 12.5 mol%） glasses doped with Eu^3＋ ions in 1 mol% are fabricated by the melting method. The Fourier transform infrared （FTIR） spectra, phonon sideband spectra, emission and excitation spectra of the glasses are measured. The crystal field parameter and coordination number of Eu^3＋ ions in the glasses are obtained according to the splitting of their ^5D0 - ^7F1 levels. The intensity parameters Ω2 and Ω4 of Eu^3＋ ions for optical transition are calculated from their emission spectra in terms of reduced matrix U^（t）（λ= 2, 4, 6） character for optical transitions. The results indicate that the intensity parameters Ω2 and Ω4 increase with the increase of Nb2O5 content, suggesting that the symmetry becomes lower, the band of Eu and O atoms becomes stronger and the covalence increases with the increase of Nb2O5 content.

关键词： Crystal symmetry Emission spectroscopy Fourier transform infrared spectroscopy Melting rare earth additions

Stable single frequency Er-doped all-fiber ring laser with fiber Bragg grating Fabry-Perot filter

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Chinese Optics Letters 2005年第4期3卷 212-214页

作者：吕昌贵王元恽斌峰崔一平 Department of Electronic EngineeringSoutheast University Nanjing 210096

Using a fiber Bragg grating (FBG) and a Fabry-Perot cavity composed of two fiber Bragg gratings (FBGFP) as its frequency-selective components, a type of single frequency all-fiber ring laser permits oscillation only on one longitudinal mode of the main cavity without modehopping while the cavity length can be up to tens of meters. The salient feature is due to the single narrowband resonance of the FBGFP filter. Such a fiber ring laser is achieved experimentally, and the laser mode is limited inside the single resonance of the FBGFP.

关键词： Erbium Fiber Bragg gratings Frequencies Laser applications Optical fiber coupling Optical filters rare earth additions Resonance Ring lasers Telecommunication