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Towards understanding the carbon trapping mechanism in copper by investigating the carbon-vacancy interaction 下载免费PDF全文
We propose a vacancy trapping mechanism for carbon-vacancy (C-V) complex formation in copper (Cu) according to the first-principles calculations of the energetics and kinetics of C-V interaction. Vacancy reduces charge density in its vicinity to induce C nucleation. A monovacancy is capable of trapping as many as four C atoms to form CnV (n=1,2,3,4) complexes. A single C atom prefers to interact with neighboring Cu at a vacancy with a trapping energy of 0.21 eV. With multiple C atoms added, they are preferred to bind with each other to form covalent-like bonds despite of the metallic Cu environment. For the CnV complexes, C2V is the major one due to its lowest average trapping energy (1.31 eV). Kinetically, the formation of the CnV complexes can be ascribed to the vacancy mechanism due to the lower activation energy barrier and the larger diffusion coefficient of vacancy than those of the interstitial C. 相似文献
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Role of helium in the sliding and mechanical properties of a vanadium grain boundary:A first-principles study 下载免费PDF全文
The effects of helium (He) on the sliding and mechanical properties of a vanadium (V) E5(310)/[001] grain boundary (GB) have been investigated using a first-principles method. It has been found that He was energetically favorable sitting at the GB region with a segregation energy of -0.27 eV, which was attributed to the special atomic configurations and charge density distributions of the GB. The maximal sliding energy barrier of the He-doped GB was calculated to be 1.73 J/m^2, 35% larger than that of the clean GB. This suggested that the presence of He would hinder the V GB mobility. Based on the thermodynamic criterion, the total energy calculations indicated that the embrittlement of V GB would be enhanced by He segregation. 相似文献
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用激光增强电离光谱(LEIS)方法进行钠原子的灵敏检测 总被引:2,自引:1,他引:1
用脉冲可调谐染料激光共振激励火焰中的钠原子。通过测量钠原子的激光增强电离光谱(LEIS)信号进行钠原子的灵敏检测,实际的检测限可达10~(-11)g/ml。 相似文献
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在β-环糊精、氢氧化钠的水介质中,由间溴硝基苯直接合成3,3'-二溴氧化偶氮苯(1),其结构经1H NMR表征.采用X-射线单晶衍射仪测定了1的晶体结构,属单斜晶系,P2(1)空间群,晶胞参数为:a=0.79596(11)nm,b=0.58620(8)nm,c=2.5968(4)nm,α=90°,β=95.781(2)°,γ=90°,V=1.2055(3)nm3,Z=4,F(000)=688,Mr=356.02,Dc=1.962 g·cm-3,μ=6.708 mm-1,R1=0.0311,wR2=0.0766. 相似文献
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应用第一性原理计算方法研究了碳(C)原子对钨(W)中氢(H)原子稳定性的影响. 本征W中, 当C-H间距离为~2.5 Å时, H的溶解能出现最低值, 此时为H最稳定的位置. W中存在空位时, 由于C的影响, H占据的最佳电子密度面值为0.10 Å-3. 研究发现, W中单空位最多能容纳10个H原子, 且不能形成H分子, 不同于没有C存在的情况, 表明C对W中H稳定性存在很大影响. 此外, 当两个C原子存在于空位中时, H占据的最佳电子密度面值变为0.13 Å-3. 相似文献
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