Polymeric sulfides CdS,CuS, and NiS in polyvinyl alcohol matrix

Cadmium, copper, and nickel sulfides have been synthesized in a polyvinyl alcohol matrix. The specimens have been investigated by means of vibration spectroscopy and X-ray diffraction analysis. The obtained data have confirmed the formation of cadmium sulfide with a polymeric chain structure in polyvinyl alcohol. The possibility of producing similar materials based on copper and nickel sulfides has been discussed.     

过渡金属TM(V,Cr,Mn)掺杂ZnS的电子结构和磁性

采用基于密度泛函理论(DFT)的第一性原理赝势平面波方法,对过渡金属V、Cr、Mn 掺杂ZnS的超晶胞体系进行了几何结构优化,计算了晶格常数、电子结构与磁学性质。研究结果表明：掺入V,Cr后,ZnS表现出明显的半金属性,而掺入Mn后,半金属性不明显;掺入过渡金属TM(V,Cr,Mn)后系统产生的磁矩主要有杂质的3d态电子贡献,且磁矩的大小与过渡金属的电子排布有关。     

Electronic structure of amorphous transition metal alloys

The electrical resistivity, the Hall coefficient and the magnetic susceptibility of amorphous alloys (Metglass 2826A, Allied Chemical) have been measured above room temperature. The experimental data show strong similarities with liquid alloys.     

Electronic structure and stability of binary transition metal compounds

It is shown that the ordered structures occurring in binary substitutional transition metal alloys on simple lattices (f.c.c., b.c.c.) can systematically be obtained from the electronic structure of the disordered alloys. Generalized structural maps are introduced; their physical meaning and their relation to the phenomenological structural maps used previously by other authors are discussed.     

X-ray appearance potential spectra and electronic structure of transition metals

The possibility of determining the density-of-states distribution function in the unoccupied part of the conduction bands of the transition metals Cr, Mo and W from experimental APS spectra is considered. Comparison of the results obtained with data from band-structure calculations for these metals is carried out.     

Electronic structure,chemical bonding and X-ray photoelectron spectra of heavy rare-earth oxides

The electronic structure of the heavy RE sesquioxides from Sm₂O₃ to Lu₂O₃ has been studied by the cluster discrete variational X method and X-ray photoelectron spectroscopy. The interpretation of XPS spectra basing on the MO model is given. An analysis of the dependence of Ln 4f orbitals contribution to chemical bonding on the lanthanide atomic number and bond lengths is made.     

Electronic structure,chemical bonding and X-ray photoelectron spectra of light rare-earth oxides

The electronic structure of the light RE oxides CeO₂, Pr₂O₃ and Nd₂O₃ has been studied by the cluster discrete variational DV-X method and X-ray photoelectron spectroscopy. The interpretation of XPE spectra basing on the MO model is given. The various electronic states contributions to the chemical bonding in the oxides are investigated.     

Electronic structure and optical absorption spectra of CdSe covered with ZnSe and ZnS epilayers

Using the first-principles methods we compute the electronic structure and the absorption spectra for a wurtzite CdSe (0001) slab covered with zincblende ZnSe and ZnS epilayers. For each structure we compute the DOS and the imaginary part of the dielectric function. We find that the semiconductor passivation shifts the ‘near Fermi-level’ states of the bare CdSe slab down to lower energy levels. The migration suggests the decrease of surface effects and energy loss. We observe the substantial reduction of the abnormal peaks in the absorption spectra of the bare CdSe slab, which seems to be a consequence of the DOS migration. This is consistent with the experimental results that a proper passivation enhance the luminescence efficiency. We also study the case that the epilayer surface is terminated with PH₃ and find the PH₃ passivation also reduces the surface state to some extent.     

过渡金属TM(V,Cr,Mn)掺杂ZnS的电子结构和磁性

采用基于密度泛函理论(DFT)的第一性原理赝势平面波方法,对过渡金属V、Cr、Mn掺杂ZnS的超晶胞体系进行了几何结构优化,计算了晶格常数、电子结构与磁学性质.研究结果表明:掺入V,Cr后,ZnS表现出明显的半金属性,而掺入Mn后,半金属性不明显;掺入过渡金属TM(V,Cr,Mn)后系统产生的磁矩主要有杂质的3d态电子贡献,且磁矩的大小与过渡金属的电子排布有关.     

Electronic structure of LiMnO : X-ray emission and photoelectron spectra and band structure calculations

The electronic structure of LiMnO₂ and Li₂MnO₃ was studied by means of X-ray photoelectron and soft X-ray emission spectroscopy. For LiMnO₂, LSDA and LSDA+U calculations were carried out. The LSDA+U calculations are in rather good agreement with the measured valence-band structure as well as with the magnetic and electrical properties of LiMnO₂. It is shown that the band gap in LiMnO₂ is determined by the charge-transfer effect. Received 15 March 1999 and Received in final form 14 July 1999     

Electronic structure of transition metal monoantimonides: Analogy to the transition metals

A simple metallic band model is proposed for the transition metal monoantimonides, by analogy to the transition metals. It is assumed that the metal 3d electrons are itinerant in narrow bands which energetically overlap broader antimony 5p-derived bands, and the Fermi level lies in the overlap region. Consistency of the model with available data is assessed and found to be quite good.     

过渡金属掺杂钛酸纳米管的电子结构和光学性质研究

采用平面波超软赝势方法计算了过渡金属(TM)(Fe,Co或者Ru)掺杂钛酸纳米管的电子结构及光学性质.对TM取代钛酸纳米管层间间隙位H+的几何结构进行优化,发现掺杂对几何结构的影响较大,其中Co或者Ru掺杂的形成能均较低.此外,掺杂的TM与周围的O原子成键,有形成固熔体的趋势.掺杂后的能带结构分析表明:Fe,Co或者Ru掺杂导致钛酸纳米管禁带宽度减小并且于禁带中引入了新的能级,这主要归因于b1g(dx2-y2)及a1g(dz2)态的出现;部分杂质能级处于半填充状态,成为空穴的俘获中心,减少电子和空穴的复合;掺杂后,价带顶向低能方向移动,使价带中形成的空穴氧化性更强.最后,掺杂的钛酸盐纳米管的吸收光谱显示,Ru掺杂的钛酸纳米管导致其在可见光范围内有更强的吸收.     

Electronic structure of twinned ZnS nanowire

The electronic properties of twinned ZnS nanowires （NWs） with different diameters were investigated based on first-principles calculations. The energy band structures, projected density of states and the spatial distributions of the bottom of conduction band and the top of the valence band were presented. The results show that the twinned nanowires exhibit a semiconducting character and the band gap decreases with increasing nanowire diameter due to quantum confinement effects. The valence band maximum and conduction band minimum originate mainly from the S-p and Zn-s orbitals at the core of the nanowires, respectively, which was confirmed by their spatial charge density distribution. We also found that no heterostructure is formed in the twinned ZnS NWs since the valence band maximum and conduction band minimum states are distributed along the NW axis uniformly. We suggest that the hexagonal （2H） stacking inside the cubic （3C） stacking has no effect on the electronic properties of thin ZnS NWs.     

Electronic structure of twinned ZnS nanowires

The electronic properties of twinned ZnS nanowires (NWs) with different diameters were investigated based on first-principles calculations. The energy band structures, projected density of states and the spatial distributions of the bottom of conduction band and the top of the valence band were presented. The results show that the twinned nanowires exhibit a semiconducting character and the band gap decreases with increasing nanowire diameter due to quantum confinement effects. The valence band maximum and conduction band minimum originate mainly from the S-p and Zn-s orbitals at the core of the nanowires, respectively, which was confirmed by their spatial charge density distribution. We also found that no heterostructure is formed in the twinned ZnS NWs since the valence band maximum and conduction band minimum states are distributed along the NW axis uniformly. We suggest that the hexagonal (2H) stacking inside the cubic (3C) stacking has no effect on the electronic properties of thin ZnS NWs.     

Electronic structure and resonant X-ray emission spectra of carbon shells of iron nanoparticles

The electronic structure of carbon shells of carbon encapsulated iron nanoparticles carbon encapsulated Fe@C has been studied by X-ray resonant emission and X-ray absorption spectroscopy. The recorded spectra have been compared to the density functional calculations of the electronic structure of graphene. It has been shown that an Fe@C carbon shell can be represented in the form of several graphene layers with Stone-Wales defects. The dispersion of energy bands of Fe@C has been examined using the measured C Kα resonant X-ray emission spectra.     

Electronic structure and X-ray photoelectron spectra of TiC and ZrC: Cluster and band structure approaches

The electronic structure for titanium and zirconium monocarbides have been calculated with the SCF MS X_α-cluster method. The results are compared with the experimental X-ray photoelectron spectra and augmented plane wave (APW) calculations.     

XPS studies of ion-bombardment damage of transition metal sulfides

Radiation damage to the surface of transition metal sulfides under ～1-keV ion bombardment has been investigated by photoelectron spectroscopy. Under     

Electronic energy structure and X-ray spectra of GaN and BxGa1-x N crystals

The electronic energy structures of GaN wurtzite and zinc-blende modifications and B_xGa_1-x N solid solutions are calculated using the local coherent potential method and the cluster version of the muffin-tin approximation in the framework of the multiple-scattering theory. The electronic structures of binary GaN crystals and ternary B_xGa_1-x N solid solutions are compared, and their features are interpreted. The boron concentration dependences of the width of the upper subband of the valence band, the band gap, and the bulk modulus of B_xGa_1-x N solid solutions (x = 0.25, 0.50, 0.75) are studied, and these dependences are shown to be nonlinear.