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Rapid Dendrite growth in Solidification of Highly Undercooled Alloys

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Journal of Wuhan University of Technology(Materials Science) 2021年第2期36卷 259-261页

作者：安红恩 YANG Jine ZHANG Xiaobing YANG Shaopei College of Mechanical and Electronic Engineering Huanghe Jiaotong UniversityJiaozuo 454950China Jiangsu Yingchuang Power Technology Co. Ltd.Suzhou 215000China Henan Engineering Technology Research Center on Intelligent Manufacturing Technology and EquipmentJiaozuo 454950China

Nonequilibrium thermodynamics and transportation kinetics near the propagating solid-liquid interface dominates the rapid solidification process,which is far from a thermodynamically stable *** solidification process can be described more precisely using quantitative thermodynamic calculation of phase diagram with nonlinear liquidus and solidus and evaluating the nonequilibrium effect in diffusion *** on these basic principles,we used a current nonequilibrium dendrite growth model to describe rapid solidification process of deeply undercooled *** of the key fundamental solidification parameters was also evaluated.

关键词： solid solutions solidification growth from melt natural crystal growth

growth,Structure,and Spectroscopic Characteristics of the Nd^(3+):LiGd(WO_4)_2 Crystal

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Chinese Journal of Structural Chemistry 2011年第1期30卷 85-96页

作者：黄新阳王国富 Institute of Research on the Functional Matter Jiangxi University of Finance and Economy Institute of Research on the Structure of Matter Chinese Academy of Sciences

The Nd^3＋：LiGd（WO4） 2 crystal with dimensions of 25mm×28mm×16mm was grown by the top-seeded solution growth method from the 60 mol% Li2W2O7 flux. LiGd（WO4） 2 crystallizes in the tetragonal system with space group I41/a（C4h^6） and cell parameters： a = 5.1986 and c = 11.2652A. The hardness is about 5.0 Mohs＇ scale. The specific heat is 0.40 J·g^-1·K^-1 at 50 oC. The thermal expansion coefficients for a-and c-axes are 1.314×10^-5 and 2.052×10^-5 K^-1,respectively. The room-temperature polarized absorption and emission spectra and the fluorescence decay curve was measured. The parameters of oscillator strengths,the spontaneous transition probabilities,the fluorescence branching ratios,the radiative lifetimes,and the emission cross sections have been investigated based on Judd-Ofelt theory and Füchtbauer-Ladenburg method. The absorption cross-section is 5.19×10^-20 cm^2 at 805 nm for π-polarization and its line width is 15 nm; the emission cross section is 1.726×10^-19 cm^2 at 1060.5 nm for π-polarization. The fluorescence and radiative lifetimes are 86 and 158 μs,respectively. The fluorescence quantum efficiency is 54.43%.

关键词： optical microscopy growth from melt Nd^3+:LiGd(WO4)2 crystal solid state laser materials

Structural and photoluminescence studies on europium-doped lithium tetraborate(Eu:Li2B4O7)single crystal grown by microtube Czochralski(μT-Cz)technique

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Chinese Physics B 2016年第5期25卷 429-433页

作者： A Kumaresh R Arun Kumar N Ravikumar U Madhusoodanan B S Panigrahi K Marimuthu M Anuradha GRD Centre for Materials Research PSG College of TechnologyCoimbatoreIndia Department of Physics PSG College of TechnologyCoimbatoreIndia Radiation Safety Division Indira Gandhi Centre for Atomic ResearchKalpakkamIndia Department of Physics Gandhigram Rural UniversityDindigulIndia PSG Institute of Advanced Studies CoimbatoreIndia

Rare earth europium（Eu（3＋））-doped lithium tetraborate（Eu：Li_2B_4O_7） crystal is grown from its stoichiometric melt by microtube Czochralski pulling technique（μT-Cz） for the first time. The grown crystals are subjected to powder x-ray diffraction（PXRD） analysis which reveals the tetragonal crystal structure of the crystals. UV–vis–NIR spectral analysis is carried out to study the optical characteristics of the grown crystals. The crystal is transparent in the entire visible region, and the lower cutoff is observed to be at 304 nm. The existence of BO_3 and BO_4 bonding structure and the molecular associations are analyzed by Fourier transform infrared（FTIR） spectroscopy. The results of excitation and emission-photoluminescence spectra of europium ion incorporated in lithium tetraborate（LTB） single crystal reveal that the observations of peaks at 258,297, and 318 nm in the excitation spectra and peaks at 579, 591, 597, 613, and 651 nm are observed in the emission *** chromaticity coordinates are calculated from the emission spectra, and the emission intensity of the grown crystal is characterized through a CIE 1931（Commission International d＇Eclairage） color chromaticity diagram.

关键词： crystal growth optical material growth from melt photoluminescence study