材料期刊网

Synthesis and Characterization of Some Substituted Arylimidazole Derivatives

Zhiqiang ZHANG , Ren HE , Peng LEI , Yan GAO , Haijun CHI , Zhizhi HU

材料科学技术（英文）

The incorporation of the imidazole nucleus is an important strategy in pharmaceuticals, chemiluminescence and electroluminescence. A facile synthesis of some aryl substituted imidazole derivatives from substituted benzils and substituted benzaldehydes via Debus reaction is described. Their structures were identified by IR, MS, NMR and their characteristics were evaluated by UV-visible and fluorescence spectroscopy.

关键词: Synthesis , null , null

Crystal structure and photoluminescence of Tb3+ doped Y3GaO6

Journal of Alloys and Compounds

A solid solution with formula (Y1-xTbx)(3)GaO6 (x = 0-0.5) was prepared by solid-state reaction method. Powder X-ray diffraction (XRD) shows that Y3GaO6 is isostructural to Gd3GaO6 (Cmc2(1)), and the lattice parameters are a = 8.8364(1) angstrom, b = 11.0899(1) angstrom and c = 5.3937(1) angstrom. Atomic parameters were derived by Rietveld refinement of the XRD pattern. Photoluminescence (PL) spectra show a strong green emission of 543 nm from the D-5(4) -> F-7(5) transition of Th3+ at room and liquid nitrogen temperature. There is a wide saturation range of the PL intensity for the Th3+ content from x = 0.04-0.20, and a long life time about 1200 mu s for the green 543 nm emission at room temperature. (c) 2006 Elsevier B.V. All rights reserved.

关键词: Y3GaO6;crystal structure;Tb3+ doped;photoluminescence;luminescence properties;dependence;y3al5o12;phosphor;ions;ce3+;tb-3;uv

A systematic study on crystal structure and magnetic properties of Ln(3)GaO(6) (Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er)

Journal of Solid State Chemistry

The crystal structures of a series of compounds with the composition Ln(3)GaO(6)(Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) synthesized by solid-state reaction at 1400degreesC are investigated. X-ray diffraction shows that Ln3GaO6 has a non-centro symmetric orthorhombic structure (space group Cmc2(1)). Lattice parameters a, b, c and cell volume and the average distances between Ln(l)-O, Ln(2)-O of these compounds decrease with the decreasing of the radii of trivalent Ln ions, which accord with the expected lanthanide contraction behavior. There are two sites of seven-fold coordination for Ln atoms with oxygens, and Ga atoms are in oxygen tetrahedra which are distorted and elongated along the a-axis. Magnetization measurements indicate that the susceptibility X changes with temperature in Curie-type manner. (C) 2004 Elsevier Inc. All rights reserved.

关键词: Ln(3)GaO(6);crystal structure;Rietveld refinement;X-ray diffraction;garnets

Optical spectra of Ln(3+)(Nd3+, Sm3+, Dy3+, Ho3+, Er3+)-doped Y3GaO6

Journal of Luminescence

Ln(3+) (Ln = Nd, Sm, Eu, Gd, Dy, Ho, Er)-doped Y3GaO6 compounds were prepared by solid-state reaction, and their optical spectra such as absorption, photoluminescence, excitation and time-resolved spectra have been measured for Ln Nd, Sm, Dy, Ho, Er. X-ray powder diffraction shows that the lattice parameters of the compounds (Y(0.96)Ln(0.04))(3)GaO6 decrease with the decrease of the radii of trivalent Ln(3+) ions, indicating that Ln(3+) ions have substituted for y(3+) ions in the lattice. Optical spectra show that there are obvious absorptions at ultraviolet to visible region. The strong emissions in visible and infra-red region show that Y3GaO6 is a suitable host for rare-earth-doped laser crystal and phosphor materials. (C) 2004 Elsevier B.V. All rights reserved.

关键词: crystal-field;absorption-spectra;luminescence;y3ga5o12;glasses;garnet;y2o3;ions;laf3;tb3

Optical properties of (Y1-xTmx)(3)GaO6 and subsolidus phase relation of Y2O3-Ga2O3-Tm2O3

Journal of Solid State Chemistry

A serial of samples in Y2O3-Ga2O3-Tm2O3 pseudo-ternary system are prepared by solid-state chemical reaction method. The range of solid solution in (Y1-xTmx)(3)GaO6 is 0 < x < 0.384. Powder X-ray diffraction shows that the compounds crystallize in Gd3GaO6 (Cmc2(1))-type structure. The solid solubilities of Y3+xGa5-xO12 (x = 0-0.77) and Tm3+xGa5-xO12 (x = 0-0.62) are 37.5-47.11 at% Y2O3, and 37.5-45.26 at% Tm2O3, respectively. PL spectra of Tm-doped Y3GaO6 show that there is a sharp blue emission at similar to 456 nm from the D-1(2) -> F-3(4) transition at room temperatures with two lifetimes (similar to 5 and similar to 15 mu s) and a narrow saturation range of PL intensity for the Tm3+ content from x = 0.005 to 0.03. The sharp emission and long lifetime of (Y1-xTmx)(3)GaO6 indicate that Y3GaO6 is a potential phosphor and laser crystal host material. (c) 2005 Elsevier Inc. All rights reserved.

关键词: Tm3+ -doped Y3GaO6;Y2O3-Ga2O3-Tm2O3 system;(Y1-xTmx)(3)Ga5O12 solid;solution;luminescence;crystal-structure;luminescence;phosphor;cations;ions;tb3

不同温度下碳源对AOA-SBR工艺PAO与GAO竞争释磷的影响

张兰河 , 李德生 , 王旭明 , 张海丰

硅酸盐通报

为了提高生物除磷效率,研究采用AOA-SBR工艺进行了长期连续除磷实验,考察不同温度下碳源(乙酸钠、丙酸钠、葡萄糖)对PAO与GAO竞争的影响.结果表明:当温度由10℃升高至25℃时,利用丙酸钠作为碳源时,污泥含磷量与含糖量分别从7.2％和5.1％升高至7.9％和6.3％,PHA转化量升高了23.1 mg/L,厌氧释磷量从105.9 mg/L升高至149.9 mg/L,VSS/MLSS由71％降低至65％;利用乙酸钠作为碳源时,污泥含磷量与含糖量分别从6.9％和5.3％升高至7.6％和6.7％,PHA转化量升高了23.9 mg/L,厌氧释磷量从73.8 mg/L升高至108.8 mg/L,VSS/MLSS由73％降低至71％;利用葡萄糖作为碳源时,污泥含磷量与含糖量分别从5.8％和6.3％升高至6.6％和8.8％,PHA转化量升高了33.2 mg/L,厌氧释磷量从37.4 mg/L升高至43.2 mg/L,VSS/MLSS由80％升高至88％.当温度升高至30℃时,3个反应器均出现厌氧末期PHA浓度下降和糖原浓度升高,厌氧释磷量减少,污泥含磷量均下降,污泥含糖量上升,VSS/MLSS均很高.与葡萄糖相比,采用乙酸钠和丙酸钠作为碳源,有利于PAO生长繁殖,PAO为优势菌种,抑制GAO增殖.同时,低温更有利于PAO的生长繁殖.

关键词: 温度 , 碳源 , SBR , PAO与GAO

Cu-Zr/ZrN薄膜体系的电阻率和纳米压入研究

白宣羽 , 汪渊 , 徐可为

稀有金属材料与工程

采用磁控溅射方法在Si(111)基片上沉积Cu-Zr/ZrN薄膜体系作为扩散阻挡层.通过比较Cu-Zr/ZrN薄膜体系和三元非晶(Mo,Ta,W)-Si-N的电阻率,同时比较Cu-Zr/ZrN薄膜体系和Ta,YaN的硬度,说明作为扩散阻挡层的材料的选取,应从整体性能上考虑,而不能仅仅考虑热稳定性等单一指标.

关键词: 非晶 , 电阻率 , 纳米压入 , 硬度

Mg单原子替位掺杂β-Ga2O3的电子结构和光学性质计算研究

宋庆功 , 徐霆耀 , 杨宝宝 , 郭艳蕊 , 陈逸飞

材料导报 doi:10.11896/j.issn.1005-023X.2015.18.027

宽禁带半导体β-Ga2O3因其出色的物理化学性能而备受关注,通过掺杂改善β-Ga2O3性能一直是研究的热点.采用基于密度泛函理论的第一性原理方法,利用广义梯度近似加U对Mg单原子掺杂β-Ga2O3体系的晶体结构、电子结构和光学性质等进行了研究和分析.总能量和结合能的对比显示:单原子替位掺杂β-Ga2O3时,Mg优先替代八面体位的Ga原子形成Mg-Gao体系.电子结构显示,Mg-Gao体系变为间接半导体,带隙变窄为4.672eV;其自旋极化率为100％,呈现半金属特性.作为光学材料,Mg-Gao体系可在紫外、深紫外区域工作,并且折射率、反射率和吸收率有所降低,透射率明显提高.

关键词: Mg掺杂β-Ga2O3 , 第一性原理 , 晶体结构 , 电子结构 , 光学性质

Hardness of T-carbon: Density functional theory calculations

Physical Review B

We reconsider and interpret the mechanical properties of the recently proposed allotrope of carbon, T-carbon [Sheng et al., Phys. Rev. Lett. 106, 155703 (2011)], using density functional theory in combination with different empirical hardness models. In contrast with the early estimation based on Gao et al.'s model, which attributes to T-carbon a high Vickers hardness of 61 GPa comparable to that of superhard cubic boron nitride (c-BN), we find that T-carbon is not a superhard material, since its Vickers hardness does not exceed 10 GPa. Besides providing clear evidence for the absence of superhardness in T-carbon, we discuss the physical reasons behind the failure of Gao et al.'s and Simunek and Vackar's (SV) models in predicting the hardness of T-carbon, residing in their improper treatment of the highly anisotropic distribution of quasi-sp(3)-like C-C hybrids. A possible remedy for the Gao et al. and SV models based on the concept of the superatom is suggested, which indeed yields a Vickers hardness of about 8 GPa.

关键词: superhard rhenium diboride;elastic-constants;ambient-pressure;metal;borides;crystals;diamond;search;boron

Studies of the g factors and the local structure for Ni3+in LaAl0.9Ni0.1O3, La0.75Y0.25Al0.99Ni0.01O3 and YAl0.9Ni0.1O3

Radiation Effects and Defects in Solids

The electron paramagnetic resonance g factors and the local structure for Ni3+ in LaAl0.9Ni0.1O3 (LAN), La0.75Y0.25Al0.99Ni0.01O3 (LYAN) and YAl0.9Ni0.1O3 (YAN) are theoretically studied from the perturbation formulas of the g factors for a 3d7 ion of low spin (S = 1/2) in tetragonally elongated octahedra. In these formulas, the contributions to the g factors from the tetragonal distortion, characterized by the tetragonal field parameters Ds and Dt are taken into account. According to the calculations, the ligand octahedra around Ni3+ are suggested to suffer 2% relative elongation along the [001] (or C4) axis due to the Jahn-Teller effect.

关键词: defect structures;electron paramagnetic resonance;crystal-fields and;spin Hamiltonians;Ni3+;LaAlO3;LaYAlO3;YAlO3;atomic screening constants;optical-spectra;paramagnetic-resonance;superconducting tapes;lattice-distortions;superposition model;scf;functions;cr3+ ions;crystals;epr