材料期刊网

SOME DEVELOPMENTS IN RAPIDLY SOLIDIFIED ALUMINUM ALLOYS FOR ELEVATED TEMPERATURE APPLICATIONS

P.Y. Li , S.L. Dai , C.Y. Li and B.C. Liu Beijing Institute of Aeronautical Materials , P.O.Box 81 2 , Beijing 150001 , China

金属学报(英文版)

Therecent developments in elevated temperature ( ET) aluminum alloys prepared by therapidsolidification / powder metallurgy ( RS P/ M) process were reviewed briefly. TheRS P/ METaluminum alloyscan beclassified as(a) the aluminum transition metaltype, such as Al Fe, Al Cr, Al Ti, Al Zrsystem alloys,etc.,and (b) thealuminum rareearth elementtype,such as Al Y, Al Nd system alloys,etc. Among them ,the Al Fe and Al Ti system alloysarethe most attractive, which possessthe potentialto replacethetitanium alloy partson aircraft,engines,etc.,fortheuseattemperaturesrangingfrom 200 315℃. Theproblemsin applicationsfor RS P/ M ETaluminum alloys werealso discussed .

关键词: rapidsolidification / powder metallurgy , null , null , null

Li1+xV3-yMyO8(M=Mo,P)高温阴极放电性能的研究

曹笃盟 , 李志友 , 周科朝

稀有金属材料与工程

采用固相反应法制备了Li1+xV3-yMyO8(M=Mo,P;0≤y≤0.4),研究了不同Mo和P含量对Li1+xV3O8相的影响,并首次对其进行了高温阴极放电性能的研究.结果表明:Mo和P掺杂量分别为y≤0.2和y＜0.2时可获得纯Li1+xV3O8相;Mo掺杂使Li1+xV3O8峰值电压提高0.3 V,比容量提高25%,嵌入的Li+量最高可达x=3.8;P掺杂(y≤0.20)对Li1+xV3O8的峰值电压和比容量影响较小.化学嵌锂实验也证实掺杂后的材料具有更快的Li+嵌入速度.

关键词: Li1+xV3O8 , 热电池 , 掺杂 , 比容量

大爆炸核合成相关的8Li(d, p)9Li反应截面测量

李志宏 , 柳卫平 , 白希祥 , 郭冰 , 连钢 , 颜胜权 , 王宝祥 , 陆昀 , 曾晟 , 苏俊

原子核物理评论 doi:10.3969/j.issn.1007-4627.2005.01.006

利用8Li次级束测量了质心系能量7.8 MeV 2H(8Li, 9Li)1H反应的角分布, 导出了8Li(d, p)9Li反应的天体物理S因子及9Li→8Li+n虚衰变的渐近归一化系数.

关键词: 8Li(d,p)9Li反应 , 角分布 , 天体物理S因子 , 渐近归一化系数

Electrical Properties of Li-doped P-type ZnO Ceramics

A.H. Salama

材料科学技术（英文）

Li-doped p-type ZnO ceramics were prepared by conventional methods according to the chemical formula Zn_1-x Li_xO₂ where x=0.5, 1.0, 1.5 and 2.0 mole fraction, respectively. The crystal structures of the prepared samples were studied by X-ray diffraction analysis. The dielectric properties (including dielectric constant ε'
and dielectric loss ε") and dc-electrical conductivity [σ(Ω^-1·cm^-1)] were investigated. The dielectric constant ε' was sharply decreased at the low frequency range and independent on frequency at high frequency range. Otherwise, the dielectric loss "00 varied with frequency and showed absorption peak located from 200 Hz to
4 kHz and moved to higher frequency as the concentration of Li⁺ doped increased. It was found that dc-electrical conductivity log¾ varied from -9 to-5 and the energy gap width were calculated by using Arrhenius equation. The p-type conductivity of Li-doped ZnO may be attributed to the formation of a LiZn-Li_i donor complex, which is limited by reducing the amount of Li_i.

关键词: P-type ZnO ceramics

Y3+掺杂Ce∶Li6Lu(BO3)3闪烁体的发光性能研究

孙丹丹 , 潘尚可 , 任国浩 , 吴云涛 , 商珊珊 , 张国庆

无机材料学报 doi:10.3724/SP.J.1077.2013.12735

针对Ce:Li6Lu(BO3)3晶体有效原子序数(zeff)高的问题,采用低原子序数的Y3+离子部分置换晶体中的Lu3+离子.通过固相合成法制备了Ce:Li6Lu1-xYx(BO3)3(0≤x≤1)固溶体.X射线粉末衍射(XRD)分析表明,该系列固溶体结构与Li6Gd(BO3)3晶体相同,空间群为P21/c.其X射线激发发射(XSL)的发光强度随着Y3+的含量增加而降低,当x=0.5时,固溶体的有效原子序数与Li6Gd(BO3)3闪烁体相当,但XSL发光强度是其1.4倍.Ce:Li6Lu0.5Y0.5(BO3)3的XSL光谱和PL光谱都在400 nm附近出现Ce3+离子的特征峰,可拟合出361和419 nm两个发光分量,分别对应于Ce3+离子的激发态电子的5d1→2F5/2和5d1→2F7/2能级跃迁.Ce:Li6Lu0.5Y0.5(BO3)3固溶体的衰减时间比Ce:Li6Lu(BO3)3略长,为19.6 ns.当x=0.50～0.70时,Ce:Li6Lu1-xYx(BO3)3(0≤x≤1)闪烁体比较适合作为中子探测材料.

关键词: 固相合成 , Ce∶Li6LU1-xYx(BO3)3 , X射线激发发射谱 , PL光谱 , 衰减时间

Li、N共掺杂实现P型ZnO的机理探讨

杨昊 , 范广涵 , 李军

材料科学与工程学报

采用基于密度泛函理论的第一性原理赝势法计算了本征ZnO、N掺杂、Li掺杂以及Li、N共掺杂ZnO的能带结构、电子态密度和差分电荷分布.计算结果表明:N掺杂的受主能级局域性较强,导致N溶解度较低,Li替位原子受主能级较浅,但是会受到Li间隙原子的补偿.Li、N共同掺入时,N_o-Li_(Zn)复合受主结构并不是ZnO的主要P型来源,N_o受主可以与间隙原子Li_i形成N_o-Li_i结构,该结构可促进N的掺入,并抑制Li_i施主的补偿效应,因而对实现ZnO的P型非常有利.

关键词: ZnO , 第一性原理 , 密度泛函理论 , 双受主共掺杂

Li+掺杂对Y2SiO5∶Pr3+上转换发光性能影响

刘成 , 杨毅 , 韩正玉 , 武晓雅 , 翁景霞 , 林璐

中国稀土学报 doi:10.11785/S1000-4343.20130408

采用溶胶-凝胶法制备Li+掺杂改性的Y2SiO5:Pr3+上转换发光材料,考察了Li+掺杂对样品晶型及发光性能的影响.采用XRD,DSC-TGA,FS对所制备的材料进行表征,结果表明Li+掺入浓度在7％～ 8％(摩尔分数)之间会引起Y2SiO5晶体类型由X型转变为X2型,且Li+掺入后样品转晶型温度由950℃降至800℃;样品经800℃煅烧处理后以X1型Y2SiO5为主相,850℃煅烧处理后以X2型Y2SiO5为主相;Li+掺入同时会提高Y2SiO5:Pr3+材料的上转换发光强度,Li+最佳掺杂浓度为10％,对于双掺杂pr3+,Li+:Y2SiO5体系中pr3+最佳掺杂浓度为1.2％.

关键词: 溶胶-凝胶法 , 上转换 , 晶相转变 , 锂掺杂 , 稀土

Y 对8090Al-Li 合金拉伸性能和断裂行为的影响

桂全红 , 马禄铭 , 蒋晓军 , 梁国军 , 李依依

材料研究学报

研究了两种不同Y 含量对8090Al-Li 合金拉伸性能及断裂行为的影响。实验表明:加入0.1wt-%Y 可在不降低强度的情况下提高合金的塑性,加入0.5wt-%Y 可在不降低塑性的情况下提高合金的强度。在峰值时效条件下,不加Y 的合金断裂为穿晶韧窝型和沿晶塑性混合方式,并伴有沿晶二次裂纹,加0.1%Y 不改变合金断裂模式,但使沿晶成分减少;加0.5%Y 合金则发生快速剪切断裂。本文从晶粒结构角度对断裂行为提出了解释。

关键词: A—Li 合金 , rare earth element Y , tensile properties , intergranular fracture , transgranular fracture

添加Y对Mg-3.5%Li合金冲击变形行为的影响

沙桂英 , 刘翠云 , 刘腾 , 孙晓光 , 李根

材料工程 doi:10.3969/j.issn.1001-4381.2010.07.014

利用Hopkinson压杆技术对Mg-3.5%Li及Mg-3.5%Li-0.77%Y合金在不同应变率下进行了冲击压缩实验,分析了两种合金的动态应力-应变行为及其应变率效应.结果表明,随应变率提高,Mg-3.5%Li合金的应力-应变行为表现出应变率强化效应与应变率弱化效应的双重特性.添加稀土元素Y后,合金有所强化,但其应力-应变行为仍具有应变率弱化效应,随应变率提高产生的微裂纹引起的内部损伤是导致合金应变率弱化效应的主要原因.

关键词: Mg-Li合金 , Mg-Li-Y合金 , 应变率 , 微裂纹

Subsolidus phase relations of the ZnO-Li(2)O-P(2)O(5) system

Journal of Alloys and Compounds

As a systematic search for suitable flux to grow zinc oxide single crystals, the subsolidus phase relations of the ternary system ZnO-Li(2)O-P(2)O(5) were investigated by means of X-ray diffraction (XRD). There are 6 binary compounds, 5 ternary compounds and 17 three-phase regions in this system. A new compound, Li(6)Zn(P(2)O(7))(2), is found in this system based on XRD experiments. The phase diagrams of the pseudo-binary systems Li(3)PO(4)-ZnO and LiZnPO(4)-ZnO are investigated. It shows that the compounds, Li(3)PO(4) and LiZnPO(4), are not suitable as flux for the growth of ZnO single crystals below 1250 degrees C. (C) 2009 Elsevier B.V. All rights reserved.

关键词: ZnO-Li(2)O-P(2)O(5) system;Zno semiconductor;X-ray diffraction;Phase;diagram;lithium zinc phosphate;oxide crystal-growth;flux research;single-crystals;zno crystals;alpha-liznpo4;gamma-li3po4;equilibria;polymorph;liznpo4