Based on the density functional theory （DFT）, the electronic structures and optical properties of Mg2Pb are calculated by using the local density approximation （LDA） and plane wave pseudo-potential method. The calculation results show that the indirect band gap width of Mg2Pb is 0.02796 eV. The optical properties of MgzPb have isotropic characteristics, the static dielectric function of Mg2Pb is ε1（0） = 10.33 and the refractive index is n0 = 3.5075. The maximum absorption coefficient is 4.8060×10^5 cm-1. The absorption in the photon energy range of 25-40 eV approaches to zero, shows the optical colorless and transparent behaviors.
The adsorption of low-coverage of F and Cl adatoms on the Mg（0001） surface was investigated using first-principles calculations based on the density functional theory（DFT）.The stability of the（2×2） structures formed by halogen atoms adsorbed at different sites was determined.The difference between the adsorption of F and Cl on Mg（0001） surface was also discussed.The calculation results show that hollow sites are the energetically most favorable at the low-coverage.It can be concluded from the Mulliken charges and density of states that electrons transfer from the substrate Mg atoms to the adatoms,which leads to the formation of adsorbate bond and further causes the stronger interaction between Mg atom and adatom.The interaction between Cl and Mg atoms is weaker than the interaction between F and Mg.
用Al和Al_2O_3双靶磁控共溅射工艺在抛光铝合金衬底上制备了Al-Al_2O_3复合涂层,同时制备纯Al涂层作对比。利用X射线衍射仪和场发射扫描电镜研究了Al-Al_2O_3复合涂层的微观结构和形貌,通过划痕实验和电化学腐蚀实验对复合涂层的膜基结合力和耐腐蚀性能进行了测试。结果表明,Al-Al_2O_3复合涂层呈较强的Al(111)择优取向,Al_2O_3相以非晶形式存在。直流功率PDC恒定时,射频功率PRF增大,复合涂层中Al相晶粒更加细化,涂层的平整度和致密度明显提高。Al-Al_2O_3复合涂层与铝合金衬底的结合力良好,可达到43 N。相比纯Al涂层,Al-Al_2O_3复合涂层具有优异的耐腐蚀性,其中PRF=150 W的复合涂层的耐腐蚀性能最佳,腐蚀电流密度为0.0016 m A/cm^2,该值相比纯Al涂层降低了一个量级。
The thermodynamics properties and thermal conductivity of Mg2Pb at high pressures have been calculated by first-principles.The enthalpy of formation and heat capacity obtained at 0 GPa are in good agreement with the experiments and other theoretical results.The thermal conductivity and coefficient of thermal expansion of Mg2 Pb at high pressure were evaluated.The thermal conductivity presents a second-order polynomial with pressure.The calculated thermal conductivity of Mg2Pb indicates that it is suitable to be used as thermal conductor at 0 K.
