Beijiang ZHANG
,
Guimin LU
,
Jianzhong CUI
材料科学技术（英文）
The relationship between electromagnetic frequency and microstructures of continuous casting aluminum alloys was studied. 7075 aluminum alloy ingot of 100 mm in diameter was produced by electromagnetic continuous casting process, the microstructures of as-cast ingot was examined by scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). The results showed that electromagnetic frequency greatly influenced segregation and microstructures of as-cast ingot, and product quality can be guaranteed by the application of a proper frequency. Electromagnetic frequency plays a significant role in solute redistribution; low frequency is more efficient for promoting solution of alloying elements.
关键词:
Continuous casting
,
null
,
null
,
null
洪智亮
,
成来飞
,
鲁琳静
,
张立同
,
王一光
无机材料学报
doi:10.3724/SP.J.1077.2010.00186
采用溶胶-凝胶法制得三种镥硅酸盐体系粉体材料. 以氧化物的摩尔比来表示此三种粉体, 分别为：Lu2O3·SiO2、Lu2O3·2SiO2和Lu2O3·2.26SiO2. 在1400℃、50%H2O-50%O2静态常压气氛下, 研究了它们的耐水蒸气腐蚀性能.以单位面积重量变化率表征材料的耐水蒸气腐蚀性能, 结合X射线衍射（XRD）、傅里叶红外光谱（FTIR）和扫描电镜能谱分析（SEMEDS）等分析手段, 揭示了镥硅酸盐体系在高温水蒸气环境中的腐蚀机制和反应机理. 结果表明：三种原始粉体主要物相依次为：Lu2SiO5+Lu2Si2O7、 Lu2Si2O7+SiO2和Lu2Si2O7+SiO2. 在水蒸气作用下, Lu2SiO5相与Al2O3反应生成新相Lu3Al5O12, 而Lu2Si2O7相并未受到水蒸气的作用而发生任何反应, 表现出优异的化学稳定性.
关键词:
Lu2SiO5
,
Lu2Si2O7
,
environmental barrier coating (EBC)
,
water vapor corrosion
洪智亮
,
成来飞
,
鲁琳静
,
张立同
,
王一光
无机材料学报
doi:10.3724/SP.J.1077.2010.00186
采用溶胶-凝胶法制得三种镥硅酸盐体系粉体材料.以氧化物的摩尔比来表示此三种粉体,分别为:Lu_2O_3·SiO_2、Lu_2O_3·2SiO_2和Lu_2O_3·2.26SiO_2.在1400℃、50%H_2O-50%O_2静态常压气氛下,研究了它们的耐水蒸气腐蚀性能.以单位面积重量变化率表征材料的耐水蒸气腐蚀性能,结合X射线衍射(XRD)、傅里叶红外光谱(FTIR)和扫描电镜能谱分析(SEM-EDS)等分析手段,揭示了镥硅酸盐体系在高温水蒸气环境中的腐蚀机制和反应机理.结果表明:三种原始粉体主要物相依次为:Lu_2SiO_5+Lu_2Si_2O_7、Lu_2Si_2O_7+SiO_2和Lu_2Si_2o_7+SiO_2.在水蒸气作用下,Lu_2SiO_5相与Al_2O_3反应生成新相Lu_3Al_5O_(12)而Lu_2Si_2O_7相并未受到水蒸气的作用而发生任何反应,表现出优异的化学稳定性.
关键词:
Lu_2SiO_5
,
Lu_2Si_2O_7
,
环境障碍涂层
,
水蒸气腐蚀
马畅
,
李晓东
,
董宇
,
刘绍宏
,
朱琦
,
李继光
,
霍地
,
孙旭东
中国稀土学报
doi:10.11785/S1000-4343.20130411
以Lu(NO3)3和尿素为原料,采用均相沉淀法合成镥盐前驱体,研究Lu3+浓度、尿素/Lu3+摩尔比R对前驱体形貌的影响.结果表明,在反应温度为95℃时,低Lu3+浓度有利于单分散球形粉体的合成,并且适当的调整R值可将单分散球形颗粒尺寸控制在180 ～ 270 nm之间.在此基础之上,研究Eu3+掺杂Lu2O3单分散球形荧光粉体的合成,探讨了Eu3+的掺杂量(1％,3％,5％,7％,9％(原子分数))及煅烧温度(600～ 1200℃)对颗粒形貌及其荧光性能的影响.结果表明,Eu3+的掺杂使所得(Lu,Eu)盐前驱体颗粒尺寸远小于单纯的Lu盐前驱体,且Eu含量对荧光粉的荧光强度有着显著的影响,荧光淬灭浓度为5％.在考察的煅烧温度范围内,荧光粉的荧光强度随煅烧温度的提升而增强.
关键词:
Lu2O3
,
Eu3+
,
均相沉淀
,
单分散球形
,
前驱体
,
荧光性能
,
稀土
Journal of Magnetism and Magnetic Materials
Magnetization curves of the ternary tetragonal compound Lu2Fe14C were measured in an extracting-sample magnetometer in the temperature range from 1.5 to 300 K. The temperature dependence of the magnetic properties of Lu2Fe14C is discussed.
关键词:
anisotropy
Quan Li
材料科学技术（英文）
Porous silicon nitride ceramics (Si3N4) were fabricated by pressureless sintering using different particle size of silicon nitride powder. Lu2O3 was used as sintering additive. According to phase relationships in the ternary system Si3N4-SiO2-Lu2O3, porous Si3N4 ceramics with different phase composition were designed through the change of the content of SiO2 which was formed by the oxidation at 800°C in air. Porous Si3N4 with different phase compositions was obtained after sintering at 1800°C in N2 atmosphere. A small content of SiO2 favored the formation of secondary phase Lu4Si2O7N2, while large content of SiO2 favored the formation of secondary phase Lu2Si2O7 and Si2N2O. Porous Si3N4 ceramics with secondary phase Lu4Si2O7N2 had a flexural strength of 207 MPa, while that with secondary phase Si2N2O and Lu2Si2O7 had lower flexural strength.
关键词:
Porous silicon nitride ceramics
邱华军
,
施鹰
,
谢建军
,
谢杰
人工晶体学报
本文以水、丙酮、乙醇、乙二醇为溶剂,采用溶剂热法制备了不同形貌的纳米氧化镥(Lu2O3粉)粉体前驱体,将前驱体在400～800 ℃条件下煅烧2 h制得了不同形貌的Eu3+:Lu2O3粉体.研究发现,所用溶剂的物理性质对产生特定形貌的样品具有重要的影响,以水和丙酮为溶剂,可制得具有较高长径比的Lu2O3纳米棒,而当溶剂为乙醇和乙二醇时,所得Lu2O3粉体为等轴状的纳米颗粒.
关键词:
溶剂热法
,
氧化镥
,
纳米粉体
,
形貌
张明举
,
李文明
,
郑树凯
中国有色金属学报
doi:10.19476/j.ysxb.1004.0609.2017.05.012
采用基于密度泛函理论(DFT)的第一性原理平面波超软赝势(PWPP)方法,模拟计算未掺杂,Lu、F单掺杂及Lu-F共掺杂ZnO的几何结构、能带结构、态密度分布、光吸收谱和介电常数等性质.结果表明:掺杂后ZnO的晶格常数发生畸变,晶胞体积增大,禁带宽度不同程度地减小;在光学性质方面,F单掺杂较Lu单掺杂和Lu-F共掺杂时在可见光区的吸收系数和反射低,反映前者在可见光范围具有较高的透射率.
关键词:
ZnO
,
第一性原理
,
共掺杂
,
电子结构
,
光学性质
Pengfei Zhang Litong Zhang Xiaowei Yin
材料科学技术（英文）
To improve the corrosion resistance of porous Si3N4 used in the high temperature environments, which contain water vapor and volatile species, porous Si3N4-Lu2Si2O7 composite ceramics were fabricated by a process of oxidation bonding and pressureless sintering in flowing N2 atmosphere at the temperatures lower than 1550°C. The pores in ceramics were formed by removing the pore-forming agent (phenolic resin). SiO2 derived by the oxidation of Si3N4 at 1250°C in air reacted with Lu2O3 at various sintering temperatures, leading to the formation of Lu2Si2O7 with excellent oxidation and corrosion resistance. The phase composition, microstructure, and mechanical properties of the porous ceramics depended on the sintering temperatures. Si3N4-Lu2Si2O7 composite ceramics with the porosity of 52% and the pore size of 0.2μm were obtained by oxidation bonding at 1250°C for 1 h and pressureless sintering at 1550°C for 2 h using 4 wt pct Lu2O3 additive.
关键词:
Porous ceramics
,
氮化硅
,
焦硅酸镥
,
无压烧结
师全林
,
白涛
,
刘杰
,
商建波
,
张小林
,
代义华
原子核物理评论
doi:10.11804/NuclPhysRev.33.04.518
175Lu(n,2n) 174m,gLu(n,2n) 173Lu反应在高能中子通量监测中具有重要作用,其产物的放射性活度通常用HPGe探测器测量,这就需要174m,gLu和173Lu的半衰期和γ射线发射率等衰变数据必须准确无误.在主要的评价核数据库中,只有ENDF/B 7.1和JEFF 3.1.1数据库给出了173Lu和174Lu的半衰期和γ射线的发射几率等衰变数据,其中173Lu的γ射线发射几率ENDF/B 7.1库比JEFF 3.1.1库总体偏高,其他评价数据两个数据库非常一致.在中国原子能研究院的串列加速器上用20 MeV质子辐照金属Yb靶生产了含有173Lu,174m,gLu的放射性溶液,用激光共振电离质谱(LRIMS)和热表面电离质谱(TIMS)两种同位素稀释法测定了该溶液中173Lu和174m,gLu核素浓度,然后制备测量源在HPGe探测器上进行了近7年的跟踪测量,发现173Lu的半衰期为1.45 a,比目前评价的数据1.37 a高6.1％,636.1 keV γ射线发射几率的偏差最大,比ENDF/B 7.1的评价数据偏高7％.174gLu半衰期的测量结果3.37 a,比评价数据3.31 a高约1.8％,174gLu 76.5 keV和1 241.8 keV γ射线的发射几率比ENDF/B 7.1的评价数据分别低1.87％和12.8％.
关键词:
173Lu
,
174Lu
,
半衰期
,
γ射线发射几率
,
HPGe
