材料期刊网

MICROSTRUCTURAL EVOLUTION OF HIGHLY UNDERCOOLED EUTECTIC Ni78.6Si21.4 ALLOY

Y.P. Lu , null , null , null , null

金属学报(英文版)

A large undercooling level up to 550k (0.386TE) was achieved in eutectic Ni78.6Si21.4 melt by the combination of molten-glass and cyclic superheating. A microcrystalline structure is obtained at large undercooling. Surprisingly, the morphology of a(Ni) phase transits from the non-faceted phase to faceted phase at large undercooling of 390K . Based on the classical nucleation theory and transient nucleation theory, the process of microstructure evolution and competitive nucleation was analyzed, and the refinement of crystal structure is determined by the high nucleation rate under large undercooling.

关键词: high undercooling , 融融玻璃 , 共晶 , 快速凝固

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

Yb0.005Y0.708Lu0.287VO4混晶的生长和材料性质

张炳涛 , 滕冰 , 钟德高 , 曹丽凤 , 李建宏 ,

人工晶体学报

采用提拉法生长出Ybb0.005Y0.708Lu0.287VO4晶体.在室温下,对Yb0.005Y0.708Lu0.287VO4晶体进行了XRPD测试,计算了晶格常数(a=b=0.7091 nm,c=0.6273 nm)和密度(4.826 g/cm3).对混晶的(100)面进行了腐蚀,腐蚀坑呈四棱锥形状.平均线膨胀系数α1=1.285×10-6 K-1,α3=7.030 ×10-6 K-1,温度在330.15 K和570.15 K之间变化时,比热为0.494 ～0.617 J/g·K.

关键词: 钒酸盐晶体 , 腐蚀坑 , 膨胀系数 , 比热 , 热导率

P507萃取色层法提取高纯Lu2O3影响因素研究

杨桂林 , 蒋广霞 , 李桂珠 , 罗永 , 刘定冕

稀有金属 doi:10.3969/j.issn.0258-7076.1999.01.015

研究了淋洗液酸度、柱径和长径比、杂质Yb2O3含量、萃淋树脂粒径、稀土载量、柱型等因素对Cl-P507萃取色层法分离提取高纯Lu2O3的影响,采用双柱串联的方法制备出>99.9999%Lu2O3.

关键词: 氧化镥提纯 , 萃取色层 , P507萃淋树脂

Lu_xY_1-xAl ₃:Ce晶体中伴生(Lu,Y₃ Al₅O₁₂:Ce相成因研究

丁栋舟 , 陆晟 , 潘尚可 , 张卫东 , 王广东 , 任国浩

无机材料学报 doi:10.3724/SP.J.1077.2008.00434

采用提拉法制备了Lu_xY_1-xAlO₃:Ce晶体样品, 通过XRD物相分析和成分分析, 并结合Lu₂O ₃-Al₂O₃二元体系相图以及Lu_xY_1-x AlO₃:Ce结构稳定性方面的分析与讨论, 结果表明: 随着熔体中Lu元素含量的增加, 熔体分层加剧, 析晶Lu_xY_1-xAlO₃:Ce相的熔体组成区间将向富Lu一侧偏移, 这使得晶体上部易伴生(Lu,Y)₃Al₅O₁₂:Ce相; 而随着Lu元素含量的提高, Lu_xY_1-xAlO₃:Ce晶体的热稳定性降低, 氧空位的存在则使晶体的热稳定性进一步降低, 在接种过程中籽晶表面易发生相分解反应生成(Lu,Y)₃ Al₅O₁₂:Ce和(Lu,Y) ₄ Al₂O₉:Ce, 籽晶表面相分解产物(Lu,Y)₃Al₅O₁₂:Ce提供了诱导析晶(Lu,Y)₃Al₅O₁₂ :Ce相所需的晶核, 这使得晶体的外
表面处易伴生(Lu,Y)₃Al₅O₁₂:Ce相. 调整配料组成使 n(Lu,Y)₂O₃ ): n (Al₂O₃)=1.17～1.00, 加大熔体内部和固液界面处的温度梯度以改善熔体对流、抑制熔体分层以及籽晶表面处的相分解等有助于高Lu元素含量Lu_xY_1-xAlO₃ :Ce晶体的获得.

关键词: 铝酸钇镥晶体 , perovskite , garnet , accompany

LuxY1-xAlO3:Ce晶体中伴生(Lu,Y)3Al5O12:Ce相成因研究

丁栋舟 , 陆晟 , 潘尚可 , 张卫东 , 王广东 , 任国浩

无机材料学报 doi:10.3321/j.issn:1000-324X.2008.03.004

采用提拉法制备了LuxY1-xAlOa:Ce晶体样品,通过XRD物相分析和成分分析,并结合Lu2O3-Al2O3二元体系相图以及LuxY1-xAlO3:Ce 结构稳定性方面的分析与讨论,结果表明:随着熔体中Lu元素含量的增加,熔体分层加剧,析晶LuxY1-xAlO3:Ce相的熔体组成区间将向富Lu一侧偏移,这使得晶体上部易伴生(Lu,Y)3Al5O12:Ce相;而随着Lu元素含量的提高, LuxY1-xAlO3:Ce晶体的热稳定性降低,氧空位的存在则使晶体的热稳定性进一步降低,在接种过程中籽晶表面易发生相分解反应生成(Lu,Y)3Al5O12:Ce和(Lu,Y)4Al2O9:Ce,籽晶表面相分解产物(Lu,Y)3Al5O12:Ce提供了诱导析晶(Lu,Y)3Al5O12:Ce相所需的晶核,这使得晶体的外表面处易伴生(Lu,Y)3Al5O12:Ce相.调整配料组成使n((Lu,Y)2O3):n(A12O3)=1.17～100,加大熔体内部和固液界面处的温度梯度以改善熔体对流、抑制熔体分层以及籽晶表面处的相分解等有助于高Lu元素含量LuxY1-xAlO3:Ce晶体的获得.

关键词: 铝酸钇镥晶体 , 钙钛矿 , 石榴石 , 伴生

Studies of the spin Hamiltonian parameters and the local structure of tetragonal Zr3+ Centers in orthophosphate MPO4 (M = Sc, Lu, Y) crystals

Zeitschrift Fur Naturforschung Section a-a Journal of Physical Sciences

The spin Hamiltonian parameters (g factors g(parallel to), g(perpendicular to) and hyperfine structure constants A(parallel to), A(perpendicular to)) of Zr3+ on the tetragonal M3+ (M = Sc, Lu, Y) sites of zircon-type orthophosphate MPO4 crystals are calculated by high-order perturbation formulas of d(1) ions in tetragonal symmetry. The crystal-field parameters are estimated by the superposition model and reasonable local structural data of impurity centers. The results show good agreement with the experimental values. It appears that in the case of size mismatch, the explanation of the spin Hamiltonian parameters of a paramagnetic impurity in crystals should take the impurity-induced local lattice relaxation into account.

关键词: EPR;spin Hamiltonian parameters;crystal-field theory;defect;structure;Zr3+;MPO4;(M = Sc, Lu, Y);electron-paramagnetic-res;d-orbital theory;superposition-model;single-crystals;cr3+ ions;ypo4;epr;lupo4;ruby;impurities

Studies of the spin-Hamiltonian parameters and defect structures for the trigonal Mo3+ centers in Y3Al5O12 and Lu3Al5O12 crystals

Radiation Effects and Defects in Solids

The complete diagonalization (of energy matrix) method (CDM) and the perturbation theory method (PTM) are applied to calculate the spin-Hamiltonian (SH) parameters (electron paramagnetic resonance g factors g(//), g(perpendicular to) and zero-field splitting D) of the trigonal Mo3+ centers in Y3Al5O12 and Lu3Al5O12 crystals. Both methods are based on the cluster approach in which the covalence effect due to the admixture between the d orbitals of central d(n) ion and p orbitals of ligands is considered. The g factors calculated by both methods are close to each other and agree with the experimental values. However, the calculated zero-field splittings D from PTM for both crystals are about 84% those from CDM. The reasons that the CDM is preferable to the PTM in the calculations of SH parameters are discussed. The angular distortions of Mo3+ centers in both garnet crystals are predicted.

关键词: defect structure;electron paramagnetic resonance;crystal and ligand;fields;Mo3+;garnets;superposition model analysis;atomic screening constants;magnetic-resonance;scf functions;jahn-teller;ions;field;spectra;sites;cr3+

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

硬脂酸盐熔融法合成(Y,Lu)AG∶Ce荧光粉及荧光性能研究

李金生 , 孙旭东 , 李晓东 , 刘绍宏 , 朱琦

无机材料学报 doi:10.15541/jim20140254

采用硬脂酸盐熔融新方法合成了[(Y1-xLux) 1-yCey]3A15O12固溶体荧光粉(x=0～0.5,y=0.005～0.03),并通过XRD、SEM、BET和PL-PLE等方法对该荧光粉进行了表征.结果表明,纯相石榴石在800℃的低温下即可生成,而不经过YAM和YAP中间相.煅烧所得[(Y1-xLUx) 1-yCey]3Al5O12荧光粉具有良好的均一性和分散性,并在455 nm蓝光激发下于544 nm附近呈现最强黄光发射.粉体的发光强度随煅烧温度升高而增大,归因于结晶度提高和表面缺陷减少.发现Ce3+的荧光猝灭浓度为1.5％,猝灭机制为Ce-Ce间的交换相互作用和晶格缺陷.发现发射峰位随Ce3+含量增加而红移,而最强激发峰和发射峰随Lu3+含量增大而蓝移,归因于Ce3+离子5d激发态能级重心移动和晶体场劈裂的共同作用.

关键词: YAG∶Ce3+ , Lu3+掺杂 , 发光性能 , 能级重心 , 晶体场劈裂