共查询到19条相似文献,搜索用时 125 毫秒
1.
采用KKR-CPA-LDA方法研究了不同混乱占位时Fe2CrGa合金基态的电子结构和磁结构. 基态能量表明Fe2CrGa合金更倾向于形成Hg2CuTi型有序结构,而不是L21结构. 能态密度(DOS)分析进一步揭示受晶体场影响的磁性原子内部交换作用是使Fe2CrGa合金形成 Hg2CuTi型有序结构的主要原因.测量了不同热处理所得Fe2CrGa合金的居里温度和分子磁矩, 发现原子占位有序化可以在137K温度范围内调控合金的居里温度.分子磁矩随有序化占位也有相应变化, 分布在2.28μB/f.u.—2.48μB/f.u.之间.理论计算和实验对比可证明Fe2CrGa合金是Hg2CuTi型Heusler合金. 相似文献
2.
3.
采用实时双光子光电子能谱和时间分辨双光子光电子能谱技术分别研究了乙醇在该表面光催化解离的动力学和超快电子动态学过程. 通过测量与乙醇光催化解离相关的电子激发态随时间的演化,发现这个反应满足分型动力学. 乙醇在还原性TiO2(110)上的光催化解离比在氧化性表面快,这归结于缺陷的存在降低了反应能垒. 这样一个反应的加速过程很可能是与缺陷电子相关的. 通过干涉双脉冲相关的测量,得到了乙醇-TiO2界面电子激发态的超快动态学. 与甲醇的情况类似,这个电子激发态的寿命为24 fs. 激发态的出现为TiO2和它周围环境的电子转移提供了一个通道. 相似文献
4.
5.
6.
7.
用反应蒸发法在玻璃等衬底上制备出铜和铟掺杂的氧化锡SnO2:(Cu,In)薄膜.对制备薄膜的发光性质做了研究,制备样品为非晶态,具无定形结构.测量了薄膜在220—1100nm范围的透过率,得到的带隙宽度Eoptg=4.645eV.室温条件下对样品进行光致发光测量,得到了显著的紫外(276—550nm)蓝绿光连续谱,通过发光谱的研究给出了这种材料的隙态分布. 相似文献
8.
9.
10.
11.
The electronic structure and magnetic properties of B-based Heusler alloys Fe2YB (Y=Ti, V, Cr and Mn) have been studied theoretically. These alloys are all ferrimagnets except for Fe2VB. The latter has 24 valence electrons and is a paramagnetic semimetal. Fe2CrB is predicted to be half-metals at equilibrium lattice constant. The spin polarization of Fe2MnB is also quite high. The calculated total moments are 1.00 μB for Fe2CrB and 2.04 μB for Fe2MnB. In Fe2CrB and Fe2MnB, the total moments are mainly determined by the partial moment of Cr or Mn. The Fe moment is relatively small and antiparallel to that of Cr or Mn. Under uniform lattice distortion, the half-metallicity of Fe2CrB is more stable than Fe2MnB, which is related to the detailed DOS structure of them near EF. 相似文献
12.
Optoelectronics research requires cheap materials with a broad spectrum of optical, electronic, and structural properties. The class of Heusler compounds and ternary structures provide many possibilities for finding alternative group IV and III–V semiconductor compounds. This study introduces wider band gap materials for use in solar cells as an alternative to cadmium sulfide buffer layers. The buffer layer is inserted between the absorber layer (p-type) and the transparent window layer (n-type) to enhance the maximum amount of light transmission. Reasonable calculations are reported for the band gaps of copper-containing materials: LiCuS, BaCu2S2, and Li2CuSb. Previous optical analysis measurements of these films determined that the band gaps were 1.8 and 1.9 eV for BaCu2S2 and LiCuS, respectively. In general, semiconductor compounds have been studied theoretically, but there are major differences between the experimental and theoretically calculated band gaps. A suitable calculation method for semiconductor compounds is described in this study. For the first time, calculations based on the Engel and Vosko method are introduced for these semiconductor compounds. This method yields band gaps that are comparable to the experimental values, which facilitate the development of microscopic analyses of these compounds. Direct band gaps of 1.15 and 1.7 eV were obtained for BaCu2S2 and LiCuS, respectively, whereas the indirect band gap was 0.7 eV for Li2CuSb. 相似文献
13.
《Current Applied Physics》2015,15(10):1117-1123
The electronic structures, magnetic properties and half-metallicity in Zr2IrZ (Z = Al, Ga, In) alloys with the Hg2CuTi-type structure were systematically investigated by using the first-principle calculations. Zr2IrZ (Z = Al, Ga, In) alloys are predicted to be half-metallic ferrimagnets which are quite robust against hydrostatic strain and tetragonal deformation. The total magnetic moment of Zr2IrZ (Z = Al, Ga, In) alloys mainly originates from the 4d electrons of Zr atoms and follows the conventional Slater-Pauling rule: Mt = Zt−18. (Mt is the total magnetic moment per unit cell and Zt is the valence concentration). The origin of the band gap for Zr2IrZ (Z = Al, Ga, In) alloys is also well studied. Unconventionally, Zr2Ir-based alloys contain element with 5d valence electrons, which implies a wider field to search for new half-metallic materials. 相似文献
14.
Hongzhi Luo Guodong Liu Fanbin Meng Jianqiang Li Enke Liu Guangheng Wu 《Journal of magnetism and magnetic materials》2012
The electronic structure and magnetic properties of new Fe-based Heusler alloys Fe2TiZ (Z = Ga, Ge, As, In, Sn and Sb) have been studied by first-principles calculations. In these alloys, the 24-electron Fe2TiGe, Fe2TiSn are nonmagnetic semiconductors and other compounds are all ferrimagnetic metals. Fe2TiAs and Fe2TiSb are predicted to be half-metals with 100% spin polarization. The spin polarization ratio in Fe2TiGa and Fe2TiIn is also quite high. The calculated total moment for Fe2TiAs and Fe2TiSb is 1 μB, which is mainly determined by the Fe partial moment. The half-metallicity of Fe2TiSb is stable under lattice distortion. The spin polarization of Fe2TiSb is found to be 100% for the lattice variation in a range of 5.6–6.1 Å, which is attractive in practical applications. 相似文献
15.
Y.C. Lin J.H. KeW.T. Yen S.C. LiangC.H. Wu C.T. Chiang 《Applied Surface Science》2011,257(9):4278-4284
In this study, Cu(In,Ga)(Se,S)2 (CIGSS) thin films were deposited onto a bi-layer Mo coated soda-lime glass by co-sputtering a chalcopyrite Cu(In,Ga)Se2 (CIGS) quaternary alloy target and an In2S3 binary target. A one-stage annealing process was performed to form CIGSS chalcopyrite phase without post-selenization. Experimental results show that CIGSS films were prepared by the proposed co-sputter process via CIGS (70 W by radio frequency) and In2S3 (30 W by direct current) with a substrate temperature of 373 K, working pressure of 0.67 Pa, and one-stage annealing at 798 K for 30 min. The stoichiometry ratios of the CIGSS film were Cu/(In + Ga) = 0.92, Ga/(In + Ga) = 0.26, and Se/(S) = 0.49 that approached device-quality stoichiometry ratio (Cu/(In + Ga) < 0.95, Ga/(In + Ga) < 0.3, and (Se/S) ≈ 0.5). The resistivity of the sample was 14.8 Ω cm, with a carrier concentration of 3.4 × 1017 cm−3 and mobility of 1.2 cm2 V−1 s−1. The resulting film exhibited p-type conductivity with a double graded band-gap structure. 相似文献
16.
基于多种实验手段和能带计算的方法, 对四元合金Fe2Co1-xCrxSi的晶体结构、 磁性、输运性质及能带结构进行了研究. 研究发现, 随着Cr的增加, 合金Fe2Co1-xCrxSi保持了高度有序结构, 逐渐从Hg2CuTi结构的Fe2CoSi 过渡到L21结构的Fe2CrSi; 由于次晶格网络的破坏, 居里温度逐渐下降; 系列合金的分子磁矩呈现线性下降, 符合半金属特性; 剩余电阻比率与原子占位有序程度密切相关, 呈现两端大、 中间小的特点. 在Cr替代Co的过程中, 材料半金属能隙逐渐打开, 表现半金属特征. 同时费米能级从Fe2CoSi半金属能隙的价带顶上移至Fe2CrSi能隙的导带底. 最大的能隙宽度出现在x= 0.75处, 这表明四元合金有可能成为具有更高自旋极化率和更强抗干扰能力的自旋电子学材料. 相似文献
17.
利用密度泛函理论方法优化了纯的和Mn原子掺杂的(MgO)n (n=2~10)团簇的几何结构. 在Mn原子掺杂的氧化镁结构中, 获得了一系列的同分异构体和与之相对应的总能量.MnMgn-1On(n=2~10)的几何构型显示Mn原子优先取代低配位的Mg原子. 结构稳定性分析表明,除了(MgO)10团簇外,其它纯的和掺杂结构的平均结合能均随着团簇的增大而增强. MnMgn-1On团簇的二阶能量差结果表明MnMg5O6和MnMg8O9比相邻的团簇表现出更高的相对稳定性. 除了MnMgO2团簇的磁矩为3.00 μB外,其它掺杂结构的磁矩均为5 μB左右. 它们的磁性主要受电荷转移大小、原子在结构中的位置以及结构尺寸所影响. 相似文献
18.
Dan Li Feng Xie Li Li Angelos Lazoudis A. Marjatta Lyyra 《Journal of Molecular Spectroscopy》2007,246(2):180-186
This paper reports our new observation of the , 13Δg (v = 2–4), and 23Πg (v = 2–8) states of 6Li7Li by continuous wave perturbation facilitated optical–optical double resonance spectroscopy. Combining our new experimental term values of 6Li7Li with the available experimental data of 6Li2 and 7Li2, molecular constants and potential energy curves by Rydberg–Klein–Rees and direct-potential-fit techniques have been determined. Born-Oppenheimer breakdown parameters of the Li2 13Δg and 23Πg states are calculated. 相似文献
19.
High aspect-ratio Li2ZrO3 nanotubes were prepared by hydrothermal method using ZrO2 nanotubes layers as templates. Characterizations of SEM, XRD, TEM and CO2 adsorption were performed. The results showed that tetragonal Li2ZrO3 nanotubes arrays containing a little monoclinic ZrO2 can be obtained using this simple method. The mean diameter of the nanotubes is approximately 150 nm and the corresponding specific surface area is 57.9 m2 g−1. Moreover, the obtained Li2ZrO3 nanotubes were thermally analyzed under a CO2 flow to evaluate their CO2 capture property. It was found that the as-prepared Li2ZrO3 nanotubes arrays would be an effective acceptor for CO2 at high temperature. 相似文献