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961.
Y. Yan J. Y. Zhang T. Cui Y. Li Y. M. Ma J. Gong Z. G. Zong G. T. Zou 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):397-403
The lattice dynamics of lithium nitride (Li3N) under high pressure are extensively investigated to probe its phase transformations by using the pseudopotential plane-wave
method within the density functional theory. A new second order α↦α′-Li3N phase transition is identified for the first time. The newly proposed α′-phase possesses a hexagonal symmetry with four ions in the unit cell having a space group of P-3m1. Further enthalpy and
phonon calculations support the existence of this phase, which stabilizes in a narrow pressure range of 2.8 – 3.6 GPa at zero
temperature. Upon further compression, transitions to denser packed phases of β-and γ-Li3N are typical first order. The analysis of the electronic densities of states suggests that all the high pressure modifications
of Li3N are insulators and, interestingly, the typical behavior of compression is to broaden the band gap. 相似文献
962.
A light-emitting diode (LED) was fabricated using a commercial InGaN LED (460 nm) and bivalent fluorescein salt dispersed in an epoxy matrix, as a primary light source and a luminescence conversion (LUCO) material, respectively. The LUCO LED emitted white light, which faded almost completely within 1 h when a current of 20 mA was continuously supplied. Based on the FT-IR, UV-visible and XPS spectral data, a large portion of bivalent fluorescein salt in the epoxy matrix underwent photochemical reactions, generating neutral fluorescein on irradiation with blue light. However, when bivalent fluorescein salt was dispersed in poly(methyl methacrylate) instead of epoxy, the luminous output of the resulting LUCO LED decreased much more slowly during continuous operation. Furthermore, the chemical structure of bivalent fluorescein salt remained unaltered during irradiation with blue light when the freeze-dried salt was kept under high vacuum. It was concluded that bivalent fluorescein salt should be almost completely protected from the environment for application as a LUCO material when coupled with a blue LED. 相似文献
963.
964.
水是一种清洁、安全、环境友好的化学反应介质,认识水介质体系中水的性质及水热化学反应对凝聚态化学的研究至关重要。水热条件下的水处于高温高压状态,其物理化学性质往往与常态下的水完全不同;因此,水热体系中可进行的化学反应范畴大为拓宽。本文介绍了水分子及其团簇的结构,水性质随条件变化的规律和特点以及水热体系中的凝聚态问题,综述了水热体系中典型的材料合成、水热有机化学反应、生物水热合成等内容,梳理了凝聚态和水热化学之间的关系,期望从凝聚态化学的角度为理解水热化学及反应体系提供一些新的思路。 相似文献
965.
建立了氧化石墨烯/壳聚糖微球吸附-电感耦合等离子体质谱法测定地质样品中痕量Ta的方法。合成了氧化石墨烯/壳聚糖微球,将其应用于地质样品中痕量Ta的分离富集,采用电感耦合等离子体质谱对富集后的试液进行测定。对氧化石墨烯含量、配体种类和浓度、pH、吸附时间、吸附剂用量等吸附条件和洗脱剂类型、体积、洗脱时间等洗脱条件进行了优化,在优化的条件下,对地质样品标准物质进行测定,Ta的方法检出限为2.0 ng/g,富集倍数为26.7倍。 相似文献
966.
基于氢键型自修复水凝胶的结构特征构建了其横截面的格气模型, 并利用Monte Carlo模拟方法对其自修复行为进行研究. 首先根据自修复过程中的比热峰值确定了氢键的临界联结分数, 然后重点考察了氢键强度、 合作效应以及平均断面间距对其自修复行为的影响. 在此基础上, 进一步研究了氢键型凝胶的动态修复过程, 讨论了相关因素对自修复时间等动态性质的影响. 结果表明, 氢键型凝胶的自修复在本质上归属于一级热力学相变, 且氢键强度是自修复过程中的最关键因素. 同时, 初始断面间距和格子间的合作效应也可显著影响凝胶的自修复行为. 相似文献
967.
Luyao Zong Fang Dong Guodong Zhang Weiliang Han Zhicheng Tang Jiyi Zhang 《Catalysis Surveys from Asia》2017,21(3):103-113
Mesoporous WO3–TiO2 support was synthesized by hydrothermal method, mesoporous V2O5/WO3–TiO2 catalyst was synthesized by impregnation method and used for selective catalytic reduction (SCR) of NOx with a excellent NOx conversion at a wider operating temperature ranging from 200 to 460?°C. In the range of 260–440?°C, NOx conversion reached to 98.6%, and nearly a complete conversion. Even with the existence of 300 ppm SO2, NOx conversion was only a little decline. The catalyst was characterized by a series of techniques, such as XRD, BET, XPS, TEM, Raman and H2-TPR. It was concluded that V2O5/WO3–TiO2 catalyst was ascribe to antase TiO2, and also the high crystallinity of anatase TiO2 could improve the SCR performance. More interested, V2O5/WO3–TiO2 catalyst exhibited the typical mesoporous structure according to the BET results. In addition, the TEM results indicated that the active components of V and W were well-dispersed on the surface of TiO2, while the enhancement of dispersion could improve the activity of catalysts. More importantly, the concentration ratio of V4+/(V5+?+?V4+?+?V3+) performed the key role in improving the activity of V2O5/WO3–TiO2 catalyst. 相似文献
968.
Wei Li Baoning Zong Xiaofang Li Xiangkun Meng Jinli Zhang 《中国颗粒学报》2007,5(1):116-120
Liquid-solid (L-S) mass transfer coefficients (Ks) were characterized in a gas-liquid-solid (G-L-S) three-phase countercurrent magnetically stabilized bed (MSB) using amorphous alloy SRNA-4 as the solid phase. Effects of superficial liquid velocity, superficial gas velocity, magnetic field strength, liquid viscosity and surface tension were investigated. Experimental results indicated that the external magnetic field increased Ks in three-phase MSB, as compared to those in conventional G-L-S fluidized beds; that Ks increased with magnetic field strength, superficial gas and liquid velocities and decreased with liquid viscosity and surface tension; and that Ks showed uniform axial and radial distributions except for small increases close to the wall. Dimensionless correlations were established to estimate Ks of the G-L-S countercurrent MSB using SRNA-4 catalyst, with an average error of 3.6%. 相似文献
969.
Li Hongbing Zong Yudong Li Xia Ding Qijun Jiang Yifei Han Wenjia 《Cellulose (London, England)》2021,28(17):10707-10714
Cellulose - Cellulose is the most widely distributed polymer material in nature and is considered a low-cost, green and recyclable material. Because of its excellent mechanical, optical and thermal... 相似文献
970.
Journal of Radioanalytical and Nuclear Chemistry - The adsorption of molybdenum (Mo) ions on ionic liquid-loaded XAD-7 resin containing 1-butyl-3-methylimidazolium(2,4,6-trimethyl)benzodithioate... 相似文献