L.P. Wang
,
B. Y Tang
,
X.B. Tian
,
YX.Leng
,
Q. YZhang
,
P.K.Chu
材料科学技术(英文)
Cerium dioxide, CeO2, is a potentially superior material in a myriad of areas, and many methods have been proposed to deposit single crystal CeO2 thin films. A novel fabrication technique utilizing dual plasma generated by metal vacuum arc (MEVVA) and radio frequency (RF) is discussed in this paper. We have recently conducted a systematic investigation to determine the optimal process window to deposit CeO2 thin films'on Si(100) substrates. The X-ray diffraction results show the existence of CeO2(100) in the as-deposited sample
关键词:
陈律
,
彭平
,
韩绍昌
稀有金属材料与工程
采用第一原理赝势平面波方法,计算了B2-YX(X=Cu,Rh,Ag,In)金属间化合物的基本物性.通过对不同点缺陷结构形成热和形成能的计算与比较,分析和预测了B2-YX金属间化合物中点缺陷结构的种类与存在形式.结果表明:B2-YX点缺陷结构主要是X子晶格上的空位与Y子晶格上的反位,在富Y的YX金属间化合物中主要为X空位,在富X的YX金属间化合物中则主要是X反位.通过对B2-YX金属间化合物完整晶体与点缺陷结构Cauchy压力参数C12-C44和G/8o值的比较,发现点缺陷能明显提高B2-YX金属间化合物的室温塑性,推测这很可能是含有点缺陷的实际B2-YX多晶材料比无缺陷理想单晶和NiAl多晶材料表现出更好室温塑性的原因之一.
关键词:
B2型Y(钇)基金属间化合物
,
点缺陷
,
第一原理
,
赝势平面波方法
,
塑性
庄厚龙
,
彭平
,
周惦武
,
刘金水
稀有金属材料与工程
采用第一原理赝势平面波方法--CASTEP程序计算了4种B2型Y基金属间化合物YX(X=Ag,Cu,In,Rh)的部分弹性性质,计算结果与文献报道值基本一致.通过Pugh定律、Cauchy压力和泊松比等经验判据,分析并预测了它们的脆性/延性,其延性高低次序为:YRh>YAg>YCu>YIn.电子结构分析表明:这4种金属间化合物良好的延性源于其较强的金属键,而不同程度的Y(d)-X(p)电子杂化则导致了其延性的差异.YIn中因In的p电子较多,杂化程度高,共价键方向性强,因而延展性最低,而YRh则由于存在Y(d)-Rh(d)电子间强的相互作用,增强了其金属键作用,因而延性最好.
关键词:
Y基金属间化合物
,
脆性/延性
,
第一原理
,
电子结构
朱永文
,
方军
,
黄真
,
高秉钧
低温物理学报
doi:10.3969/j.issn.1000-3258.2003.02.014
实验研究了La0.5Sr0.5MnO3体系La位上Y掺杂对电荷有序相的影响.结果表明掺杂量为0.15以下时,样品均呈现金属-绝缘体转变行为;当掺杂量为0.2,0.25时样品中出现了电荷有序相.通过对样品的结构和输运特性的仔细研究,发现有三种因素对其输运特性具有重要影响:带宽即〈TA〉,eg电子的轨道,无序度σ2.同时,实验结果表明电荷有序相的形成是因为电子之间的强关联作用的结果.
关键词:
电荷有序
,
强关联作用
,
带宽
,
eg电子的轨道
,
无序
乐文凯
,
袁子洲
,
徐骏
,
周子刚
机械工程材料
doi:10.11973/jxgccl201610012
采用真空单辊甩带法制备出成分为(Zr56Al16Co28)100-xYx(x=0,2,4)非晶合金,利用X射线衍射仪、差示扫描量热仪、电化学工作站、场发射扫描电镜和能谱仪等研究了钇含量对该非晶合金在 Hank′s溶液中腐蚀行为的影响。结果表明:随着钇含量的增加,该非晶合金的自腐蚀电流密度逐渐降低,耐腐蚀性能增强,但当x=4时其增大的程度较小;耐腐蚀性能的提高归因于钇的添加促进了该非晶合金表面氧化膜的持续形成。
关键词:
锆基非晶合金
,
合金化
,
钇
,
Hank′s溶液
,
耐腐蚀性
于杨
,
徐宝生
,
翁凌
,
朱兴松
,
王诚
,
刘立柱
绝缘材料
以苯并噁嗪/环氧树脂为基体,氢氧化镁为阻燃剂,制备了无卤无磷阻燃覆铜板基板材料。对基板材料的氧指数、介电性能、绝缘性能和力学性能进行测试,分析不同种类(GX105,GX110,YX105)和不同含量的氢氧化镁对基板材料性能的影响,确定了氢氧化镁的最佳类型和用量。结果表明:采用YX105为阻燃剂,其含量为10%时,制备的板材综合性能较好,其中介电常数和介质损耗因数分别为5.33和0.008,表面电阻为8.6×1012Ω,体积电阻率为1.62×1014Ω·m,弯曲强度为512.0 MPa,氧指数为37.2。
关键词:
氢氧化镁
,
阻燃剂
,
覆铜箔板
,
环境友好
International Journal of Hydrogen Energy
Electronic structure and the total energy of the Mg(NH(2))(2) were calculated using first principle theory. The bonding characteristics and decomposition mechanism of the Mg(NH(2))(2) were clarified based on the electronic structure and the total energies. The bonding interactions of the Mg atoms with the two [NH(2)] ligands are slightly different, while it shows a significant difference in the bonding interactions between the N and the H atoms within the [NH(2)] ligands. The weakest bond is the N(2)-H(2) bond in the [NH(2))(2) ligand. A decomposition mechanism of the Mg(NH(2))(2) was proposed based on the bonding characteristics. The decomposition of the Mg(NH(2))(2) is performed by two steps. First H(+) cations decompose from the [NH(2)] ligands due to their weaker bonds with the matrix, and then [NH(2)](-) anions decompose. The H(+) cations and [NH(2)](-) anions therefore react each other to generate NH(3). For the Mg(NH(2))(2) + LiH systems, it is most likely that the Mg(NH(2)) decomposes to MgNH, H(+)cation, and [NH(2)](-) anion first, and then the released H(+) cation and [NH(2)]- anion either react each other to form NH(3) and then reacts with LiH, or directly react with Li(+) cation and H(-) anion if LiH is decomposed. Both of the reactions generate the LiNH(2) and the H(2). And the LiNH(2) further mixes with MgNH to form the LiMgN(2)H(3). The is the first step of a multi-step dehydrogenation process of the Mg(NH(2))(2)-LiH system [Isobe S, Ichikawa T, Leng H, Fujii H, Kojima Y. Hydrogen desorption processes in Li-Mg-N-H systems. J Phys Chem Solids 2008;69:22234.]. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
关键词:
Magnesium amide;Electronic structure;Decomposition;n-h system;reversible hydrogen-storage;hydride;imides;li3n