材料期刊网

Effect Of Predeformation Manner On Semi-Solid Structure Of Az61 Magnesium Alloy In Sima Process

G.P. Chen , T.R. Zhou , H. Yan , F.Y. Zhang , null , null , null

金属学报(英文版)

The effect of predeformation manner, predeformation ratio and isothermal heat-treat parameter on the non-dendrite structure of AZ61 magnesium alloy in SIMA process was studied. Under coequal heat-treat condition, the impact of the hot upsetting predeformation on semi-solid microstructure in SIMA process was compared with that of the cold compressive predeformation. The results indicate that non-dendrite microstructure in AZ61 magnesium alloy billets can be obtained by hot or cold upsetting predeformation in SIMA process, although their mechanisms of evolution are different. Increasing hot or cold upsetting predeformation ratio can enhance the effect and quality of the non-dendrite microstructure formed before storage energy up to saturation, but the proper isothermal temperature and holding time should be selected.

关键词: AZ61 magnesium alloy , null

RbLn2F7的水热合成及RbLn2F7:Eu3+(Ln=Gd,Y)的VUV光谱

由芳田 , 黄世华 , 王大伟 , 黄艳 , 徐建华

中国稀土学报

利用水热方法合成出RbLn2F7(Ln=Gd,Y,Er,Yb和Lu),均为六方RbEr2F7型结构.掺杂Eu3+离子样品的光谱表明水热产物中氧杂质含量极低.在RbGd2F7:Eu3+(0.5mol%)的激发光谱中只观测到Gd3+离子f-f跃迁,Eu3+离子的激发跃迁很弱.激发Gd3+离子到6IJ能级后,观测到Eu3+离子的特征发射,Gd3+离子与Eu3+离子之间存在能量传递过程.Eu3+离子的5D0→7F1和5D0→7F2跃迁发射较强,表明稀土离子在六方RbLn2F7中处于非中心对称的格位.

关键词: RbLn2F7 , 水热合成 , 真空紫外(VUV) , 氟化物 , 能量传递 , 稀土

Y0.78Yb0.2Er0.02F3多孔纳米粒子的合成与上转换发光

杨梅 , 刘其鹏 , 李东风 , 尤洪鹏 , 洪广言

中国稀土学报

以Y2O3,Yb2O3,Er2O3,NH4F等试剂为原料,采用水热法在180 ℃下保温10 h获得了NH4Y1.56Yb0.4Er0.04F7球形纳米粒子. 所获得的纳米粒子在氮气保护下400 ℃灼烧2 h,制备出Y0.78Yb0.2Er0.02F3纳米粒子. 利用Scherrer公式计算出NH4Y2F7:Yb3+,Er3+和YF3:Yb3+,Er3+的粒径分别为65.8和68.3 nm. TEM照片展示粒子近球形,其大小与Scherrer公式计算结果一致. TEM还揭示每个粒子上面应带有许多小孔. 氮气吸附脱附实验进一步证实了粒子上存在小孔. 在980 nm的红外激光激发下,NH4Y1.56Yb0.4Er0.04F7不发光,而Y0.78Yb0.2Er0.02F3发出明亮的绿光,表明所获得的Y0.78Yb0.2Er0.02F3具有强的上转换发光.

关键词: NH4Y1.56Yb0.4Er0.04F7 , Y0.78Yb0.2Er0.02F3 , 纳米粒子 , 水热法 , 上转换发光 , 稀土

Response to the Comment on 'Conjectures on exact solution of three-dimensional (3D) simple orthorhombic Ising lattices'

Philosophical Magazine

The error of Equation (15b) in my article [Z.D. Zhang, Phil. Mag. 87 (2007) p.5309] in the application of the Jordan-Wigner transformation does not affect the validity of the putative exact solution, since the solution is not derived directly from that equation. Other objections of Perk's comment [J.H.H. Perk, Phil. Mag. 89 (2009) p.761] are the same as those in Wu et al.'s comments [F.Y. Wu et al., Phil. Mag. 88 (2008) p.3093; p.3103], which do not stand on solid ground and which I have sought to refute in my previous response [Z.D. Zhang, Phil. Mag. 88 (2008) p.3097]. The conjectured solution can be utilized to understand critical phenomena in various systems, whereas the conjectures are open to rigorous proof.

关键词: 3D Ising model;exact solution;conjecture;critical phenomena;ferromagnetism;magnetic phase transition;model;analyticity

Na(Y1.5Na0.5)F6∶Eu3+的热稳定橙色发光及荧光增强

庞涛 , 周元

功能材料 doi:10.3969/j.issn.1001-9731.2017.04.023

采用简单的水热工艺制备了六方相Na(Y1.5 Na0.5)F6∶Eu3+荧光粉.300 K温度下利用394 nm光波长激发,观察到Eu3+的5Dn(n=0,1,2)→7 FJ(J=1,2,3,4)跃迁,对应主波长590 nm,色彩饱和度约为0.97.当温度升高到420 K时,仅观察到微小的色漂移.进一步拟合Ln(I0/I-1)和10 000/T的关系曲线,确定发光的热猝灭激活能约为0.324 eV.良好的热稳定性,表明Na(Y15Na0.5)F6∶Eu3+适合于功率器件的封装.在Na(Y1.5 Na0.5)F6∶Eu3+表面包覆二氧化硅后,可观察到Eu3+增强的发光,但这种荧光增强依赖于二氧化硅壳层的厚度.利用荧光增强与荧光猝灭的竞争模型解释了上述现象.

关键词: Na(Y1.5 Na0.5)F6∶Eu3+ , 热稳定性 , SiO2包膜 , 荧光增强

CF4气氛中生长Re: LiM(Re=Tm,Ce;M=Lu,Y)F4晶体

那木吉拉图 , 阮永丰 , 苏小平 , 杨海 , 杨鹏 , 李楠

人工晶体学报

本文在CF4气氛中以提拉法成功地生长出高质量的掺入Tm3+、Ce3+的LiLuF4和LiYF4晶体,对比了Ar和CF4气氛中生长的LiYF4晶体的红外光谱特性,讨论了CF4气氛对LiM(M=Y,Lu)F4晶体生长的影响.同时测试了Tm3+、Ce3+在LiLuF4和LiYF4晶体中的有效分凝系数,从离子半径和晶胞畸变的角度,讨论了Tm3+、Ce3+在LiLuF4和LiYF4晶体中有效分凝系数差别的产生原因.

关键词: LiYF4 , LiLuF4 , 晶体生长 , 有效分凝系数

Response to 'Comment on a recent conjectured solution of the three-dimensional Ising model'

Philosophical Magazine

This is a Response to a recent Comment [F.Y. Wu, B.M. McCoy, M.E. Fisher et al., Phil. Mag. 88 (2008)] on the conjectured solution of the three-dimensional (3D) Ising model [Z.D. Zhang, Phil. Mag. 87 5309 (2007)]. Several points are made: (1) Conjecture 1, regarding the additional rotation, is understood as performing a transformation for smoothing all the crossings of the knots. (2) The weight factors in Conjecture 2 are interpreted as a novel topologic phase. (3) The conjectured solution and its low- and high-temperature expansions are supported by the mathematical theorems for the analytical behavior of the Ising model. The physics behind the extra dimension is also discussed briefly.

关键词: critical temperatures;lattices;analyticity;bounds

Y-Mg-Al-F催化剂用于1,1,1,2-四氟乙烷裂解制备三氟乙烯

赵洋 , 蔚辰刚 , 周强 , 吴周安 , 王树华 , 罗孟飞

应用化学 doi:10.3724/SP.J.1095.2014.30338

采用沉积沉淀法制备了Y-Mg-Al-F催化剂,应用XRD、NH3-TPD和Raman光谱等技术手段对催化剂进行表征,并与AlF3催化剂作比较,且将催化剂应用于四氟乙烷(HFC-134a)裂解制备三氟乙烯反应中.结果表明,1100℃焙烧的Y-Mg-Al-F催化剂具有较高的活性和反应稳定性.反应温度400℃时,四氟乙烷转化率大于25％.催化剂表面酸性和积碳是影响催化剂活性和稳定性的主要因素.

关键词: 四氟乙烷 , 催化裂解 , 三氟乙烯 , 沉积沉淀法 , Y-Mg-Al

Theoretical calculations of the optical band positions and spin-Hamiltonian parameters for Yb(3+) at the tetragonal Y(3+) site of KY(3)F(10) crystal

Physica B-Condensed Matter

The six optical band positions and six spin-Hamiltonian parameters [g factors g(parallel to), g(perpendicular to) and hyperfine structure constants A(parallel to)((171)Yb(3+)), A(perpendicular to)((171)Yb(3+)), A(parallel to)((173)Yb(3+)), A(perpendicular to)((173)Yb(3+))] for Yb(3+) ion at the tetragonal Y(3+) site of KY(3)F(10) crystal are calculated from a diagonalization (of energy matrix) method. In the method, the Hamiltonian of energy matrix contains the free-ion, crystal-field interaction, Zeeman (or magnetic) interaction and hyperfine interaction terms and so a 14 x 14 complete energy matrix for 4f(13) ion in tetragonal crystal-field and under an external magnetic field is constructed. Diagonalizing the energy matrix, these optical and EPR spectral data are calculated together and the calculated results are in reasonable agreement with the experimental values. The signs of hyperfine structure constants A(parallel to), A(perpendicular to) for the isotopes (171)Yb(3+) and (173)Yb(3+) in KY(3)F(10) are suggested. The results are discussed. (C) 2011 Elsevier B.V. All rights reserved.

关键词: Optical spectrum;Electron paramagnetic resonance;Crystal-field theory;Yb(3+);KY(3)F(10);electron-paramagnetic-resonance;epr parameters;spectroscopy;laser;spectra;ions;srf2

Jian ZHANG/Langhong Lou

材料科学技术（英文）

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