反应合成Cu//FeS复合材料摩擦磨损分子动力学模拟

通过分析摩擦磨损试验后Cu//FeS复合材料的透射电子显微镜和扫描电子显微镜照片,分别建立Cu//Cu接触表面和Cu//FeS接触表面两种模型.分子动力学模拟表明,铜铜摩擦副间主要发生黏着磨损;Cu//FeS摩擦过程中,FeS形成结实且紧密的层状结构,并且沿密排面(0001)方向滑移,且滑动只发生在中间层内部.试验结果证实Cu//FeS复合材料耐磨性能优于纯铜摩擦材料,FeS自润滑材料在铜基复合材料中起到了良好的减磨作用.     

Fe3O4P型掺杂对有机电致发光器件性能的提高

将金属氧化物Fe3O4在空穴传输材料中进行P型掺杂并制作有机电致发光器件,使器件的开启电压由5 V降至2.5 V;20 mA/cm2电流密度下的功率效率由1.2 lm/W提高到2.0 lm/W;10 V下的亮度由1 680cd/m2提高到30 590 cd/m2.紫外-可见-红外吸收光谱及紫外光电子能谱的测试分析结果表...     

Al、Zn、Mn、Zr、Ca对Mg合金电子结构影响的第一性原理研究

应用密度泛函理论研究了合金元素Al、Zn、Mn、Zr、Ca对α-Mg合金电子结构的影响。对合金元素添加后的结构进行了优化。在稳定结构的基础上,通过对不同合金元素的形成能、态密度、布居分布、差分电荷密度的分析,认为引起合金性能变化的原因是各合金元素的电负性和原子半径的大小不同所致,对比了合金元素对材料电子结构的影响,从理论上解释了Zr、Ca强烈的合金强化、细化作用。     

CuInSe2电子结构与光学性质的第一性原理计算

从头计算了CuInSe2(CIS)体相的性质,参数设定和性质计算都基于密度泛函理论,交换相关能采用GGA,泛函形式为PBE,原子间相互作用的描述采用超软赝势.计算发现CIS中存在共价键,是一种非典型的离子型晶体,在整个晶体内存在共用电子对,Cu原子和Se原子的作用大于Se原子和In原子.CIS是一种典型的直接带隙半导体,计算得到了光学性质的各项参数,包括折射指数和反射率,吸收系数以及介电函数与光子能量的关系,发现CIS的主要光吸收峰有6个,分别为:3.1,7.6,10.0,16.1,19.0,21.0 eV,理论上最强吸收峰在紫外光区.     

BaC_2异构体电子结构性质的密度泛函理论计算

第一原理计算了BaC2低温和常温两种异构体的电子结构性质,得到了二碳化钡的能带结构及电子密度.发现BaC2是典型的离子键结合晶体,认为在两种异构体中存在强C—C共价键及Ba—C离子键.分析了两种结构的Ba—C间电子密度及布居分布,认为结构中哑铃形的C2为C≡C键,在I4/mmm结构中相互作用的Ba—C2距离为0.2945nm,C2/c为0.2744nm,C≡C键长在两种晶体结构中分别为0.1185nm,0.1136nm,与C2H2中的C≡C键长相似.I4/mmm结构的能带子带拆解表明了原子亚层电子的轨道成键,讨论了C22-的电荷转移及对材料的影响.BaC2两种结构的振动谱和热力学性质计算表明,其异构体结构转变是典型的温度诱发相变,相变温度约为132K,与相关文献的预测一致.     

利用激基复合物发光的有机白光电致发光器件

以NPB为空穴传输材料,(dppy)BF为发光层,Alq为电子传输层和色度调节层,制备了有机白光电致发光器件.该器件的白光发射是来自于(dppy)BF与NPB的固界表面形成的激基复合物发光,以及NPB与(dppy)BF发射的蓝光.该白光器件的色度稳定,在电压10～25V的变化范围内,色坐标变化由(0.29,0.33)到(0.31,0.35).器件在4V开启,12V电压下亮度和效率分别为200cd/m²和0.45lm/W.     

CuInSe2电子结构与光学性质的第一性原理计算

从头计算了CuInSe₂(CIS)体相的性质，参数设定和性质计算都基于密度泛函理论，交换相关能采用GGA，泛函形式为PBE，原子间相互作用的描述采用超软赝势.计算发现CIS中存在共价键，是一种非典型的离子型晶体，在整个晶体内存在共用电子对，Cu原子和Se原子的作用大于Se原子和In原子.CIS是一种典型的直接带隙半导体，计算得到了光学性质的各项参数，包括折射指数和反射率，吸收系数以及介电函数与光子能量的关系，发现CIS的主要光吸收峰有6个，分别为：3.1，7.6，10.0，16.1，19.0，21.0eV，理论上最强吸收峰在紫外光区.     

First principles study of stability,mechanical, and electronic properties of chromium silicides

Through the first principles calculations, the chemical stability, mechanical, and electronic properties of chromium silicides are predicted. Estimating enthalpies and binding energies, density state density and electron density distribution are combined to analyse the thermodynamic stability and physical properties of chrome-silicon binary compounds. The chromium silicide includes Cr_3 Si, Cr_5 Si_3, CrSi, and CrSi_2. The chemical stability and the information about electronic structure, mechanical properties, Debye temperature, and anisotropy properties are obtained by density functional theory and Debye quasi-harmonic approximation. Meanwhile, the calculation of elastic modulus shows that Cr_3 Si has the highest body modulus value(251 GPa) and CrSi_2 possesses the highest shear modulus(169.5 GPa) and Young's modulus(394.9 GPa). In addition, the Debye temperature and the speed of sound of these Cr–Si compounds are also calculated.Since the calculated bulk modulus is different from Young's modulus anisotropy index, and also different from Young's modulus of a three-dimensional surface shape, the different mechanical anisotropies of all the compounds are obtained.     

Stability,electronic structures,and mechanical properties of Fe–Mn–Al system from first-principles calculations

The stability, electronic structures, and mechanical properties of the Fe–Mn–Al system were determined by firstprinciples calculations. The formation enthalpy and cohesive energy of these Fe–Mn–Al alloys are negative and show that the alloys are thermodynamically stable. Fe_3Al, with the lowest formation enthalpy, is the most stable compound in the Fe–Mn–Al system. The partial density of states, total density of states, and electron density distribution maps of the Fe–Mn–Al alloys were analyzed. The bonding characteristics of these Fe–Mn–Al alloys are mainly combinations of covalent bonding and metallic bonds. The stress-strain method and Voigt–Reuss–Hill approximation were used to calculate the elastic constants and moduli, respectively. Fe_(2.5)Mn_(0.5)Al has the highest bulk modulus, 234.5 GPa. Fe_(1.5)Mn_(1.5)Al has the highest shear modulus and Young's modulus, with values of 98.8 GPa and 259.2 GPa, respectively. These Fe–Mn–Al alloys display disparate anisotropies due to the calculated different shape of the three-dimensional curved surface of the Young's modulus and anisotropic index. Moreover, the anisotropic sound velocities and Debye temperatures of these Fe–Mn–Al alloys were explored.     

Effects of alloying element on stabilities,electronic structures,and mechanical properties of Pd-based superalloys

The thermodynamic stabilities, electronic structures, and mechanical properties of the Pd-based superalloys are studied by first principles calculations. In this work, we discuss the effect of Pd-based superalloys made from Al, Si, Sc, Ti,V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, Mo, Tc, Hf, Ta, W, Re, Os, Ir and Pt, and we also calculate a face centered cubic(fcc)structure 2 × 2 × 2 superalloy including 31 Pd atoms and one alloying element T M(Pd_(31)TM). The mixing energies of these Pd-Based superalloys are negative, indicating that all Pd-based superalloys are thermodynamically stable. The Pd_(31)Mn has the lowest mixing energy with a value of-0.97 eV/atom. The electronic structures of the Pd-based superalloys are also studied, the densities of states, elastic constants and moduli of the mechanical properties of the Pd-based superalloys are determined by the stress-strain method and Voigt–Reuss–Hill approximation. It is found that Pd_(31)TM is mechanically stable, and Pd_(31)Tc has the largest C_(11), with a value 279.7 GPa. The Pd_(31)Cr has the highest bulk modulus with a value of299.8 GPa. The Pd_(31)Fe has the largest shear modulus and Young's modulus with the values of 73.8 GPa and 195.2 GPa,respectively. By using the anisotropic index, the anisotropic mechanical properties of the Pd_(31)T M are discussed, and threedimensional(3 D) surface contours and the planar projections on(001) and(110) planes are also investigated by the Young modulus.