Enhancing visible-light photocatalytic activity of α-Bi2O3 via non-metal N and S doping

In recent years, some important research indicated that the visible-light activity of photocatalysts could be enhanced via incorporating p-block non-metal elements into the lattice. In this paper, we investigated the electronic structures of pure and different non-metal （C, N, S, F, Cl, and Br） doped α-Bi2O3 using first-principles calculations based on the density functional theory. The band structures, the electronic densities of states, and the effective masses of electrons and holes for doped α-Bi2O3 were obtained and analyzed. The N and S dopings narrowed the band gap and reduced the effective mass of the carriers, which are beneficial for the photocatalytic performance. The theoretical predication was further confirmed by the experimental results.     

CaWO4晶体中F型色心电子结构的研究

运用相对论的密度泛函离散变分法(DV-Xα)研究了CaWO₄晶体中F型色心的电子结构. 计算结果表明，F和F⁺心在禁带中引入了新的施主能级；分析了晶体内可能存在的光学跃迁模式，并通过过渡态的方法计算了F，F⁺心跃迁到导带底的能量分别为1.92eV和2.42eV. 因此，从理论上推断了F和F⁺心在CaWO₄晶体中可能引起650nm和515nm的吸收，由此说明CaWO₄晶体中650nm和515nm吸收带起源于晶体中的F和F⁺心. 关键词： 4晶体')" href="#">CaWO₄晶体 +心')" href="#">F和F⁺心 DV-Xα     

Semi-empirical determination of Kα1,2, Kβ1,3, and Kβ2,4 X-ray natural line widths for various elements between 29 ≤ Z ≤ 74 at 123.6 keV

Abstract

In this study, K_α1,2, K_β1,3, and K_β2,4 X-ray natural line widths for various elements were determined semi-empirically at 123.6?keV by using K shell fluorescence yields obtained from energy dispersive X-ray fluorescence measurements. The obtained results contribute to a database for the development of new theoretical models of atomic structure, radiation shielding materials, and designing new technological devices related to the structural analysis of materials. The obtained results were compared with the literature, while new fitting polynomials for the studied parameters were acquired. The results showed that the natural linewidths of K X-ray lines fit fourth-order polynomials except for K_β2,4.     

N.M.R. Spectra of the Fuchs0Nes: Structure of Naphthofuchsone

Following the initial synthesis of the fuchsones¹I, (α, η -diphenyl-1,4-benzoquinone methides), numerous substituted members of this series have been described by workers interested in triphenylmethane dyes. The fuchsones have been synthesized by the sulfuric acid condensation of benzilic acid and appropriate phenol¹, by dehydration of 4-hydroxytriphenylcarbinol², by oxidation 4-hydroxytri-phenylmethane and by photochemically induced reactions benzophenones with 2,6-dialkylphenols⁴.     

α-苯甲胺基-β-(3-吲哚基)-丙酸甲酯的合成

以L-色氨酸为原料经过4步得到α-苯甲胺基-β-(3-吲哚基)-丙酸甲酯,它是一种具有潜在的抗肿瘤活性的吲哚二酮哌嗪化合物的中间体,首先通过“酰氯法”合成L-色氨酸甲酯盐酸盐,再脱去盐酸,与苯甲醛发生缩合反应形成希夫碱,最后选择性还原,得目的产物,得率54.9%.     

Densities and mixing volumes of mixtures of fluorobenzene, α,α,α-trifluorotoluene, tert-butylmethyl ether, and ethanol at temperature 298.15 K and pressure 0.1 MPa

The volumetric properties were evaluated from density data for the binary mixtures of (fluorobenzene + tert-butylmethyl ether), (α,α,α-trifluorotoluene + tert-butylmethyl ether), (tert-butylmethyl ether + ethanol), and the ternary mixtures of (fluorobenzene + tert-butylmethyl ether + ethanol) and (α,α,α-trifluorotoluene + tert-butylmethyl ether + ethanol). The observed densities were obtained by means of a vibrating-tube densimeter at the temperature 298.15 K and the pressure 101 kPa.The excess molar volumes of the ternary mixtures were estimated from binary solution data using several empirical equations with mean standard deviation less than 0.03 cm³·mol^-1. Stable chemical cross-associations among the molecules forming the mixtures were revealed.     

Cr,Mo,Ni在α-Fe(C)中占位、键合性质及合金化效应的第一性原理研究

基于密度泛函理论第一性原理方法,采用广义梯度近似下的PW91泛函形式,计算了合金元素Cr,Mo,Ni固溶于α-Fe(C)的电子结构,从晶格畸变、结合能、态密度、重叠布居及差分电荷密度等计算结果出发探讨了合金元素在α-Fe(C)中占位、键合性质及其合金化效应,结果表明:Cr优先占据铁素体晶胞顶角位置,而Mo,Ni优先占据体心位置;Cr与晶胞的结合能最大,晶胞最稳定,Ni次之,Mo最低;Cr,Mo,Ni在晶胞中都存在金属键、共价键和微弱离子键的共同作用,成键轨道主要是Cr3d与Fe3d,Mo4d与Fe3d,Ni3d与Fe3d,C2p的交互作用形成的;Cr与晶胞原子间的键合作用强,晶胞的稳定性好,对增强钢材的机械性能帮助较大,Ni的键合作用较弱,但还是能保持晶胞的稳定性,Mo虽然键合作用强,但反键作用也非常强,使晶胞的稳定性大大降低,对钢材的机械性能危害较大.     

α-甘氨酸晶体中NH_3~+扭曲振动的变温拉曼光谱研究

1999年,Chilcott研究了α-甘氨酸单晶电阻抗随温度的变化,发现晶体在304 K开始导电。为了了解其导电机理,本文研究90 K到340 K的拉曼光谱,发现在α-甘氨酸单晶中NH3+扭曲振动模式分裂,表现为N-H(6)…O(1)(491 cm-1)和N-H(7)…O(2)(483 cm-1)模式,以及CO2-摇摆模式(503cm-1),在304 K均有不连续性变化,并与变温中子衍射晶体结构层内的氢键N-H(6)…O(1)键角和N-H(7)…O(2)长度出现转折点一致。由于α-甘氨酸晶胞中NH3+和CO2-基团构成的电偶极子在变温下重新定向,出现两性离子电荷重心变化致使晶体极化,引起晶体在304 K左右发生了铁电相变。     

Hard magnetic properties in Pr2Fe14B/α-Fe nanocomposite magnets with a combined addition of V and C

Nanostructured Pr₈Fe_86−xV_xB_6−yC_y (x=0, 1; y=0, 1) ribbons composed of Pr₂Fe₁₄B and α-Fe phases with a high coercivity are fabricated by direct melt spinning. The effects of a single addition of V and a combined addition of V and C on the structures and magnetic properties of melt-spun Pr₈Fe₈₆VB_6−xC_x (x=0 and 1) ribbons have been investigated. Compared with addition-free ribbons, 1 at% V addition is found to reduce the grain sizes of the samples and improve their magnetic properties due to a strong exchange coupling between the hard and the soft phase. A remanence ratio of 0.82, a coercive field of 6.2 kOe and a maximum energy product of 23.4 MGOe in melt-spun Pr₈Fe₈₅VB₆ ribbons are obtained at room temperature. The combined addition of V and C is found to lead to the formation of an intermediate phase of VC at grain boundaries, which appears as a pinning barrier during magnetization and results in an increase of the coercivity value to 6.9 kOe for melt-spun Pr₈Fe₈₅VB₅C ribbons.     

Solvothermal synthesis and characterization of α-Fe2O3 nanodiscs and Mn3O4 nanoparticles with 1,10-phenanthroline

α-Fe₂O₃ nanodiscs and Mn₃O₄ nanoparticles have been prepared by the 1,10-phenanthroline as complexing agent in the presence of sodium hydroxide under hydrothermal conditions. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectra. The average diameter of α-Fe₂O₃ nanodiscs is of 2 μm. In the case of Mn₃O₄ sample, the Mn₃O₄ crystallites are nanoparticles with an average size of 34 nm. A formation mechanism for the α-Fe₂O₃ and Mn₃O₄ nanomaterials was proposed.