Lihong HAN
,
Jitai NIU
,
Darning JIANG
,
Tsunernichi Imai
材料科学技术（英文）
The superplasticity of an Al(2)O(3)p/6061Al composite, fabricated by powder metallurgy techniques, has been investigated. Instead of any special thermomechanical processing or hot rolling, simple hot extrusion has been employed to obtain a fine grained structure before superplastic testing. Superplastic tensile tests were performed at strain rates ranging from 10(-2) to 10(-4) s(-1) and at temperatures from 833 to 893 K. A maximum elongation of 200% was achieved at a temperature of 853 K and an initial strain rate of 1.67x10(-3) s(-1). The highest value obtained for the strain rate sensitivity index (m) was 0.32. Differential scanning calorimeter was used to ascertain the possibility of any partial melting in the vicinity of optimum superplastic temperature. These results suggested that no liquid phase existed where maximum elongation was achieved and deformation took place entirely in the solid state.
关键词:
杨敏
,
常海萍
,
毛军逵
工程热物理学报
本文实验研究了离心力场下细微封闭循环通道中,以H2O和氟利昂R12为热驱动介质的热驱动流动规律和换热特性,重点分析了热驱动换热技果随Ra数Ro数的变化规律以及冷却效果.实验结果表明:在热流密度和旋转速度相同的条件下,采用介质R12可以获得较高的半均换热系数,冷却效果也优于以H2O为介质的冷却效果.最后建立了两种介质条件下相应的准则关系式.
关键词:
热驱动
,
热驱动介质
,
细微通道
,
旋转
,
换热系数
Chemical Physics Letters
A theoretical method for studying the inter-relation between the local structure and EPR spectra is established by diagonalizing the complete energy matrices. For [M(H(2)O)(6)]XCl(6): Mn(2+) (M = Zn, Mg, Cd, Ca; X = Pt, Sn) systems, the calculated results demonstrate that the local structures around the octahedral Mn(2+) centers in the doped systems are very similar despite of the host crystals being different. Furthermore, it is shown that the EPR zero-field parameter D depends simultaneously on the local structure parameters R and h while (a - F) depends mainly on R, whether the doped systems are at liquid-nitrogen temperature or room temperature. (C) 2008 Elsevier B.V. All rights reserved.
关键词:
electron-paramagnetic-resonance;single-crystals;spectra;field;ions;spectroscopy;copper(ii);complexes;behavior;mn(ii)
肖静
,
邓振波
,
徐登辉
,
徐颖
,
王瑞芬
中国稀土学报
将新型稀土配合物TbY(m-MOBA)6(phen)2·2H2O掺杂到导电聚合物PVK中改善了铽配合物的成膜特性和导电性质.用此掺杂体系制作了单层发光器件,发现掺杂浓度为1:5,甩膜转速为1000r·min-1时器件的发光效果最好,起亮电压为9 V,最大亮度在17 V时达到15.7cd·m-2.对比[Tb(m-MOBA)3phen]2·2H2O的单层器件的发光,说明Y3+的存在促进了PVK到Tb3+的能量传递.
关键词:
电致发光
,
铽配合物
,
激子
,
稀土
徐登辉
,
邓振波
,
张志峰
,
张梦欣
,
白峰
,
王瑞芬
中国稀土学报
将稀土铽配合物[Tb(m-MBA)3phen]2*2H2O作为发光材料应用于有机电致发光. 把铽配合物掺杂在PVK中经甩膜制得发光层, 并分别用AlQ和PBD作为电子传输层制作了两类有机电致发光器件. 器件1: ITO/PVK: [Tb(m-MBA)3phen]2*2H2O/ PBD/LiF/Al; 器件2: ITO/PVK: [Tb(m-MBA)3phen]2*2H2O/AlQ/LiF/Al, 研究了两种器件的电致发光性能, 并通过选择AlQ的厚度得到了发光性能较好的用AlQ作为电子传输材料的器件, 其最大亮度在20 V时达到140 cd*m-2.
关键词:
光学
,
电致发光
,
激子
,
稀土配合物
Solid State Communications
Samples with composition R2Fe14M3 (M = Ga and Si; R = Y, Nd, Sm, Gd, Tb, Dy, Ho, Er and Tm) have been prepared by are-melting. Crystal-structure studies have shown that the prepared samples are single phase with the rhombohedral Th2Zn17 and/or the hexagonal Th2Ni17 structure. Substitution of Ga for Fe in R2Fe17 leads to an increase of the unit-cell volume, whereas Si substitution reduces the unit-cell volume. The Curie temperatures of the R2Fe14Ga3 and R2Fe14Si3 compounds are much larger than those of the corresponding R2Fe17 compounds. The Fe moment decreases upon Ga or Si substitution. The compounds R2Fe14Ga3 and R2Fe14Si3 With R = Er and Tm exhibit a spin-reorientation transition at low temperature. (C) 1997 Elsevier Science Ltd.
关键词:
neutron-diffraction;solid-solutions;substitution;anisotropy;nd2fe17
Chemical Physics Letters
The relationship between the local structure and EPR spectrum is studied by diagonalizing the complete energy matrices for Mn(2+) in a trigonal ligand-field. The results show that the degree of distortion increases with temperature increasing whether it is compressed or elongate distortion, and the distorted tendency of the local structure is different according to the sign of D. Meanwhile, the distortion of Cd(BF(4))(2)center dot 6H(2)O:Mn(2+) system is more sensitive to temperature than that of ZnSnF(6)center dot 6H(2)O:Mn(2+) system. Moreover, the EPR parameter D is closely associated with the local structure parameters R and h while (a - F) is mainly concerned with R. (C) 2010 Elsevier B. V. All rights reserved.
关键词:
single-crystals;optical-absorption;phase-transitions;mn2+;field;ions;resonance;spectra;relaxation;fe-3+
