W.M. Ma1)
,
C.F. Qian2) and X.F. Cheng2) 1) Shenyang University
,
Shenyang 110044
,
China 2) Northeastern University
,
Shenyang 110006
,
China
金属学报(英文版)
hethesisanalysesthevalenceelectronstructuresof phase Γin Fe Zn transitionallayerof heat galvanized sheet used in cars by applying the Empirical Electron Theory of Solids andMolecules, and calculatesthebond energy ofthe major bondsand cohesiveenergy ofcrystals,from which we draw theconclusion:sincecrystal has alargercohesiveenergy, it has higherhardness, butsinceitsbondenergyisratherlow ,itiseasytobreak under pressurefrom out side, and thecrackiseasytocome up andspreadin phase Γ.
关键词:
the empirical electron theory of solids and molecules
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null
,
null
,
null
Superconductor Science & Technology
It is shown that the superconductivity in Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) compounds can be modulated by internal (chemical) pressure. The internal pressure is induced by Gd substitution for Ce in CeFeAsO(0.84)F(0.16), which compresses the crystal lattice. The temperature dependences of resistivity and magnetization show that the superconducting-transition temperature T(c) is enhanced from 40 K for CeFeAsO(0.84)F(0.16) to 47.5 K for Ce(0.6)Gd(0.4)FeAsO(0.84)F(0.16). The increase and subsequent decrease of Tc upon application of external pressure, as observed previously in LaFeAsO(0.89)F(0.11), is entirely confirmed by the modulation of Tc of the Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) superconductors by internal pressure.
关键词:
layered quaternary compound;43 k;iron
马毅斌
,
李宁
,
黎德育
,
张密林
,
黄晓梅
腐蚀学报（英文）
用电化学方法研究了Mg-14Li-1Al-0．1Ce合金在卤素溶液（NaX，X=F，C1，Br和I）中的腐蚀行为并用失重法测定其腐蚀速率，用扫描电镜（SEM）观察腐蚀后的表面形貌，利用XRD检定腐蚀产物的相组成．结果表明，合金在卤素溶液中的腐蚀速率由低到高的顺序是：NaF〈NaI〈NaBr〈NaCl．经过48h腐蚀后，合金在NaCl、NaBr和NaI溶液中的腐蚀产物层的组分为Mg（OH）2，Li3Mg7和Li0.92Mg4.08，而在NaF溶液中的腐蚀产物层的组分为Li3Mg7和Li0．92Mg4．08．此外，合金在NaF溶液中的电化学活性非常低，出现了钝化现象．电化学阻抗谱表明合金腐蚀产物层不能起到防止基体腐蚀的作用．
关键词:
镁锂合金
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腐蚀
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卤化钠
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EIS
,
XRD
Journal of Applied Physics
Structural parameters have a critical impact on superconductivity in iron-based oxypnictide superconductors. Structural evolution study was performed on Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) superconductors by the analysis of the x-ray diffraction patterns with Rietveld refinement. Substitution of Gd for Ce generates internal pressure that compresses the crystal lattice. The contraction of the c axis is also indicated by the reduction of Ce/Gd-As and Ce/Gd-O/F distances, while there is a slight increase in the As-Fe-As block size, which is compensated by a large reduction in the Ce/Gd-O/F-Ce/Gd block with Gd substitution. The diagonal Fe-As-Fe angle for Ce(0.6)Gd(0.4)FeAsO(0.84)F(0.16), with the highest T(c) among Ce(1-x)Gd(x)FeAsO(0.84)F(0.16) compounds, is 111.13 degrees. It is close to the ideal value of 109.47 degrees for the perfect FeAs tetrahedron, which is situated in the region of Fe-As-Fe bond angles where RFeAsO compounds tend to have the highest T(c). (C) 2011 American Institute of Physics. [doi:10.1063/1.3565408]
关键词:
layered quaternary compound;high-temperature superconductivity
梁庆华
,
史瑶
,
马望京
,
杨新民
,
李智
影像科学与光化学
doi:10.7517/j.issn.1674-0475.2014.02.150
X射线成像板的成像性能很大程度上取决于存储荧光粉材料的物理化学性能.本文采用水热制备方法,以BaCl2、EuBr2、NaBF4为反应原料,以乙二胺四乙酸(EDTA)为辅助剂制备了Ba7 F12 Cl2:Eu2+荧光粉.利用X射线粉末衍射(XRD)、场发射扫描电镜(SEM)、X射线能量损失谱(EDS)、拉曼光谱(Raman)、荧光光谱(PL)等对制备的Ba7 F12 Cl2:Eu2+进行了表征.根据反应条件对产物的影响,初步提出了产物的形成过程.结果表明:反应温度及EDTA用量对产物物相和形貌有显著影响;制备的Ba7 F12 C12:Eu2+荧光粉有较好的发光性能.
关键词:
荧光粉
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水热合成
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Ba7F12Cl2
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成像板
陈磊
,
冯振杰
,
曹世勋
,
张金仓
低温物理学报
本文采用第一性原理计算软件包VASP,系统地研究了不同F掺杂比例的新型层状超导体NdFxO1-xBiS2 (x=0,0.125,0.25,0.375,0.5)体系的晶格特性和电子结构,并着重研究了将Nd4f电子作为价电子引入对NdF0.5O0.5BiS2电子结构的影响和NdF0.5O0.5BiS2的磁有序结构.结果表明:引入F掺杂会减小晶格参数a的值,但随着掺杂比例的增加,a值又会逐渐增加,晶格参数c的值则保持递减的趋势;F掺杂比例为0.375时,费米能级处出现态密度峰值,意味着最佳掺杂;Nd4f电子作为价电子时会与Nd5d电子一起成为NdO(F)耗尽层中的载流子供体,不会改变BiS2超导层的电子结构;Nd子晶格局域磁矩的C-AFM型磁有序排列会大大增加体系的稳定性,成为最可能的磁性基态.
关键词:
NdFxO1-xBiS2
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电子结构
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Nd4f电子
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磁有序
陈军
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林理彬
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卢铁城
无机材料学报
本文运用嵌入原子簇的电荷自治离散变分方法（SCC－DVM－Xα方法）分别对TIO2晶体中F和F+心的能级结构进行了计算，得到了F和F+心的光学吸收跃迁模式，其跃迁能量分别是0.98、1.78eV.我们认为，经还原后的TiO2晶体，在光吸收实验中测到的1．2μm（1.02eV）、760um（1.75eV）两个峰分别是由于还原过程中形成的F和F+心的吸收峰，并存在着F→F+的转型过程．
关键词:
F
,
F+ center
,
energy level
,
transition energy
陈军
,
林理彬
,
卢铁城
无机材料学报
doi:10.3321/j.issn:1000-324X.1999.03.006
本文运用嵌入原子簇的电荷自洽离散变分方法(SCC-DVM-Xα方法)分别对TiO2晶体中F和F+心的能级结构进行了计算,得到了F和F+心的光学吸收跃迁模式,其跃迁能量分别是0.98、1.78eV.我们认为,经还原后的TiO2晶体,在光吸收实验中测到的1.2μm(1.02eV)、760nm(1.75eV)两个峰分别是由于还原过程中形成的F和F+心的吸收峰, 并存在着F→F+的转型过程.
关键词:
F
,
F+心
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能级结构
,
跃迁能量
吴世彪
,
熊华平
,
陈波
,
程耀永
材料工程
doi:10.11868/j.issn.1001-4381.2014.10.004
分别在880℃/10min和880℃/60min规范下,采用Ag Cu Ti活性钎料实现了SiO2f/SiO2复合陶瓷与C/C复合材料的真空钎焊连接,通过电子探针(EPMA)、能谱仪(XEDS)和X射线衍射仪(XRD)分析了接头微观组织,室温下测试了接头的抗剪强度.结果表明:两种规范下所得接头界面结合良好,接头中靠近两侧母材均形成了一层扩散反应层,钎缝基体主要由均匀的共晶组织组成.880℃/10min规范下钎焊接头界面产物依次为:SiO2f/SiO2 →Ti4 O7 →Ti5 Si4+ Cu(s,s)+Ag Cu共晶合金→TiC→C/C;对于880℃/60min规范下的接头,界面组织结构与保温10min的接头基本类似,但是不存在Cu(s,s),并且接头反应层明显增厚.880℃/60min条件下所得钎焊接头剪切强度平均值为16.6MPa.
关键词:
SiO2f/SiO2复合陶瓷
,
C/C复合材料
,
Ag-Cu-Ti
,
界面反应层
,
抗剪强度
