H2, CO, N2, O2和CH4在碳膜中的扩散

Diffusion of pure H2, CO, N2,O2 and CH4 gases through nanoporous carbon membrane is investigated by carrying out non-equilibrium molecular dynamics （NEMD） simulations. The flux, transport diffusivity and activation energy for the pure gases diffusing through carbon membranes with various pore widths were investigated. The simulation results reveal that transport diffusivity increases with temperature and pore width, and its values have a magnitude of 10^-7 m^2·s^-1 for pore widths of about 0.80 to 1.21 nm at 273 to 300 K. The activation energies for the gases diffusion through the membrane with various pore widths are about 1-5 kJ·mol^-1, The results of transport diffusivities are comparable with that of Rao and Sircar （J. Membr. Sci., 1996）, indicating the NEMD simulation method is a good tool for predicting the transport diffusivities for gases in porous materials, which is always difficult to be accurately measured by experiments.     

An XRD, FTIR and TPD Investigation of NO2 Surface Adsorption Sites of δ, γ Al2O3 and Barium Supported δ, γ Al2O3

In this paper an XRD, FTIR and TPD investigation of NO₂ surface adsorption sites of , Al₂O₃ and barium supported , Al₂O₃ is reported. Aim of this study is to bring additional light on the surface structures involved in NOx adsorption. Two samples of barium supported aluminas have been prepared and aged at 800 °C. These samples were characterised in comparison with the relative alumina support. The XRD characterisation of these samples shows the presence of barium carbonate and barium aluminate supported on alumina. The comparison of the FTIR spectra, before and after NO₂ adsorption, has revealed the formation, upon NO₂ contact, of a complex variety of nitrate and nitrite groups. The thermal desorption of nitrate and nitrite species has been simultaneously studied by means of FTIR spectroscopy and by TPD technique. By comparing the structural, adsorptive and spectroscopic results obtained on alumina and on barium supported alumina samples, a hypothesis on the basic sites active in NO₂ adsorption and of the possible decomposition paths induced by thermal heating are proposed.     

258.15 K下五元体系Li+,Na+,Mg2+//SO42-,Cl--H2O相平衡研究

中国含锂盐湖大部分位于青藏、新疆等干旱少雨、冬季寒冷且漫长的地区。为指导低温提锂工艺的开发和设计、利用冬季冷能进行目标离子的富集及明确含锂盐湖在低温下的析盐规律,采用等温溶解平衡法对258.15 K、二水氯化钠饱和条件下的交互五元体系Li⁺,Na⁺,Mg²⁺∥SO₄^2-,Cl^--H₂O相平衡关系进行研究并构建等温平衡相图。结果表明,相图中有4个共饱点、6个两盐结晶区(NaCl·2H₂O+Na₂SO₄·10H₂O、NaCl·2H₂O+MgCl₂·8H₂O、NaCl·2H₂O+MgSO₄·7H₂O、NaCl·2H₂O+Li₂SO₄·H₂...     

Na+,Mg2+//Cl-,SO42--H2O四元体系相平衡

针对海水淡化后浓海水综合利用问题,开展相平衡研究,提出硫酸钠水合物法增浓海水的方法。等温法测定了5℃时Na⁺, Mg²⁺//Cl^-, SO₄^2--H₂O四元体系及其子体系的相平衡溶解度数据,绘制并分析相图特征。结果表明：5℃时该体系存在2个等温共饱点和4个结晶区,十水硫酸钠结晶区形成面积较大,可用于硫酸钠水合物法增浓海水研究。相图分析和计算表明：该技术可使浓海水浓缩率高达82.78%,无水硫酸钠回收率99.6%。浓海水经精制处理后可作为制碱生产的原料,节省制碱生产过程中的化盐过程,为综合开发利用淡化后浓海水提供理论和数据基础。     

A2B2O7(A=Ln3+,B=Zr4+,Hf4+Ti4+Ce4+)型透明陶瓷研究进展

A₂B₂O₇型化合物具有高熔点、高密度和高折射率等特点,在照明材料、航空材料、医疗成像、磁光材料等领域具有潜在应用价值。随着陶瓷制备工艺的进步,透明陶瓷的光学、力学和热学等性能不断提升使A₂B₂O₇型透明陶瓷受到越来越多研究者的关注,本文介绍了一些A₂B₂O₇型透明陶瓷的制备工艺、性能参数和其潜在的应用价值。     

Dielectric,ferroelectric, magnetic and magnetoelectric properties of 0.1Ni0.8Zn0.2Fe2O4–0.9Pb1−3x/2SmxZr0.65Ti0.35O3 magnetoelectric composites

Composites having general formula 0.1Ni_0.8Zn_0.2Fe₂O₄–0.9Pb_1−3x/2Sm_xZr_0.65Ti_0.35O₃ with x=0, 0.01, 0.02 and 0.03 were synthesized by a conventional solid state reaction route. X-ray diffraction analysis was carried out to confirm the coexistence of individual phases and microstructural study was done by using a scanning electron microscope. Dielectric properties were studied as a function of temperature and frequency. To study ferroelectric and magnetic ordering in composite samples, P–E and M–H hysteresis loops were recorded respectively. Maximum magnetoelectric coupling coefficient of 22.5 mV/cm Oe was observed for sample with x=0.03. A significant improvement in dielectric, ferroelectric, piezoelectric and magnetoelectric properties was observed for Sm substitution.     

Phase formation of REBa2Cu3O7−δ (RE: Y0.5Gd0.5, Y0.5Nd0.5, Nd0.5Gd0.5) superconductors from nanopowders synthesised via co-precipitation

Phase formation of REBa₂Cu₃O_7−δ (RE: Y_0.5Gd_0.5, Y_0.5Nd_0.5, Nd_0.5Gd_0.5) superconductors synthesised via co-precipitation (COP) method were investigated by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis. All samples showed identical thermal decomposition behaviour from the thermogram in which 5 major weight losses were observed. However, XRD of the samples at different heat treatment temperatures showed different diffraction patterns indicating different thermolytic processes. Meanwhile, transmission electron microscopy and surface area analysis revealed that the powders obtained from COP have particle sizes ranging from 7 to 12 nm with relatively large surface area. Molar ratios of prepared samples obtained were near to the theoretical values as confirmed by elemental analyses using X-ray fluorescence (XRF). The T_C(R=0) for sintered YGd, YNd and NdGd were 87 K, 86 K and 90 K, respectively. Surface morphological study via scanning electron microscope showed the structures of samples were dense and non porous.     

M4R4（M=B,Al,GaR=tBu,SitBu3）异常分子结构的理论研究

采用密度泛函方法,在PBE/DZP水平上,通过与化合物C4R4、Si4[SiR3]4比较,对标题化合物的异常分子结构进行了理论研究,并计算了分子的核排斥能(PBE/6-31g**)、静电势(PBE/6-31g**)、结合能(PBE/TZP),对关键键能进行了能量分解(PBE/TZP)。计算结果表明静电吸引作用和轨道作用是B4R4,Al4[SiR3]4和Ga4[SiR3]4分子存在异常分子结构主要原因。     

Synthesis, characterization and photocatalytic activity of β-Ga2O3 nanostructures

Nanostructured β-Ga₂O₃ samples were prepared by a combination of the solvothermal processes and subsequent heat treatments. β-Ga₂O₃ samples with various morphologies were obtained by using different kinds of solvent, including water, isopropanol and ethylene glycol. One-dimensional β-Ga₂O₃ nanorods were obtained in water medium, while β-Ga₂O₃ spheres were prepared in alcohol. The possible mechanism related to the phase formation and morphology of the as-prepared materials was discussed. Photocatalytic performance of the synthesized β-Ga₂O₃ samples was also examined. Results revealed that β-Ga₂O₃ sample prepared with ethylene glycol showed the highest photocatalytic activity for the degradation of salicylic acid. This could be ascribed to the high surface area, abundant hydroxyl groups, and wide band gap of β-Ga₂O₃ sample synthesized in ethylene glycol.     

Structural,magnetic and elastic properties of Mn0.3−xMgxCu0.2Zn0.5Fe3O4 nanoparticles

In this paper, Mn_0.3?xMg_xCu_0.2Zn_0.5Fe₃O₄ (x?=?0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30) nanoparticles were prepared by the nitrate-citrate technique at low temperature. The structural, microstructural, magnetic and elastic properties of the samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, Transmission electron microscopy, field emission-scanning electron microscopy and vibrating-sample magnetometer at room temperature. Rietveld refinement of the XRD patterns indicated the formation of the single phase cubic spinel structure (space group Fd-3m) without any detectable impurity phase in all the samples that also was confirmed by FTIR studies. The lattice parameter is found to increase non-monotonically with an increase in Mg ion concentration. Also, the bond lengths and bond angles (A and B sites) of the studied ferrites were calculated by the refining of the XRD data. The values of the crystallite size decrease with increasing micro-strain (and conversely) and both of them reach extremum at x?=?0.15. The low remanence and coercivity values confirmed the formation of the superparamagnetic ferrites nanoparticles. The saturation magnetization of the samples gradually grows with Mg substitution and reach extremum at x?=?0.15. Variation of saturation magnetization with Mg content can be mainly attributed to change of cation distribution, and Yafet-Kittel angle occurred between magnetic moments on B-site in the samples. The values of Young's modulus, Debye temperature, bulk modulus, rigidity modulus of the samples were determined by the values of elastic constant and wave velocities obtained from the force constants. The improvement of the elastic properties of sample x?=?0.05 could be explained regarding the smaller values of the lattice parameter (a), the bond length and angle and the smaller crystallite size.     

Sr4Al14O25:Eu2+,Dy3+/TiO2-xNx复合材料制备及光催化性能

采用溶胶-凝胶法在长余辉发光材料(Sr4Al14O25:Eu2+,Dy3+)的表面包覆TiO2-xNx。利用X-射线衍射(XRD)、扫描电子显微镜(SEM)对复合材料的结构,形貌进行了表征;并研究了Sr4Al14O25:Eu2+,Dy3+/TiO2-xNx复合材料对甲基橙的光催化降解性能。     

Preparation, electrochemical properties, and cycle mechanism of Li1? x Fe0.8Ni0.2O2-Li x MnO2 (Mn/(Fe+Ni+Mn)=0.8) material

A new type of Li_1−x Fe_0.8Ni_0.2O₂-Li _x MnO₂ (Mn/(Fe+Ni+Mn)=0.8) material was synthesized at 350 °C in an air atmosphere by a solid-state reaction. The material had an XRD pattern that closely resembled that of the original Li_1−x FeO₂-Li _x MnO₂ ((Fe+Ni+Mn)=0.8) with much reduced impurity peaks. It was composed of many large particles of about 500–600 nm and small particles of about 100–200 nm, which were distributed among the larger particles. The Li/Li_1−x Fe_0.8Ni_0.2O₂-Li _x MnO₂ cell showed a high initial discharge capacity above 192 mAh/g, which was higher than that of the parent Li/Li_1−x FeO₂-Li _x MnO₂ (186 mAh/g). This cell exhibited not only a typical voltage plateau in the 2.8 V region, but also an excellent cycle retention rate (96%) up to 45 cycles. We suggest a unique role of doped nickel ion in the Li/Li_1−x Fe_0.8Ni_0.2O₂-Li _x MnO₂ cell, which results in the increased initial discharge capacity from the redox reaction of Ni²⁺/Ni³⁺ between 2.0 and 1.5 V region.     

白光SrMoO4:Eu3+,K+@g-C3N4荧光粉的合成及其性能研究

为了获得单一基质白光荧光粉，以三聚氰胺为原料，采用热分解法制备g-C₃N₄蓝色荧光粉，采用高温固相法制备了Sr_0.92Mo O₄:0.08Eu³⁺(SMO:E)和Sr_0.82Mo O₄:0.08Eu³⁺,0.10K⁺(SMO:EK)红色荧光粉，通过沉淀吸附反应制备了Sr_0.82Mo O₄:0.08Eu³⁺,0.10K⁺@0.013g-C₃N₄(SMO:EK-CN)复合荧光粉。利用X射线粉末衍射、红外光谱、荧光光谱、热猝灭分析对荧光粉进行表征，分别探讨了Eu³⁺单掺杂和Eu³⁺、K⁺共掺杂以及Eu³⁺、K⁺、g-C₃N₄     

α,α’-邻苯二甲基桥联茚基钐胺化物（C9H6CH2C6H4CH2C9H6）SmNPh2催化甲基丙烯酸甲酯聚合

文章以α,α’-邻苯二甲基桥联茚基钐胺化物(C9H6CH2C6H4CH2C9H6)Sm NPh2为催化剂,对甲基丙烯酸甲酯聚合反应进行了研究,考察了催化剂用量、反应时间及反应温度对甲基丙烯酸甲酯聚合的影响,并且用粘度法对聚合产物的粘均分子量进行了表征。发现α,α’-邻苯二甲基桥联茚基钐胺化物(C9H6CH2C6H4CH2C9H6)Sm NPh2对甲基丙烯酸甲酯聚合反应具有较高的催化活性。温度降低,聚合反应转化率增加,聚合产物粘均分子量升高;催化剂用量增加,聚合反应转化率增大,聚合产物的粘均分子量下降;延长反应时间,转化率和分子量都增大。     

Nd2O3对(Zr0.8,Sn0.2)TiO4微波介质陶瓷结构和性能影响

以(Zr_0.8,Sn_0.2)TiO₄为基,通过研究Nd₂O₃(0～0.20 mol%)掺杂(Zr_0.8,Sn_0.2)TiO₄微波介质陶瓷对物相结构、形貌和介电性能的影响,发现随着Nd₂O₃掺杂量的增加,(Zr_0.8,Sn_0.2)TiO₄介质陶瓷的晶格参数、晶粒尺寸变化微弱,Nd3+几乎不影响(Zr_0.8,Sn_0.2)TiO₄陶瓷阳离子有序生长,而是在(Zr_0.8,Sn_0.2)TiO₄介质陶瓷的晶界形成钉扎,通过降低介质外在损耗,有效提高陶瓷材料的Q×f值至45000(@15 GHz),并提高容量温度稳定性。     

掺杂RE3+对CaAl2O4:Eu2+,Nd3+发光性能的影响

以燃烧法合成了CaAl2O4∶Eu2+,Nd3+,RE3+紫色长余辉发光材料。实验结果表明,掺杂辅助激活剂Pr3+和Ce3+对CaAl2O4∶Eu2+,Nd3+磷光体发光性能有明显影响。掺杂Pr3+的CaAl2O4∶Eu2+,Nd3+样品的发射峰蓝移;掺杂Ce3+的CaAl2O4∶Eu2+,Nd3+样品的发射峰红移。Pr3+或Ce3+掺杂,可以提高CaAl2O4∶Eu2+,Nd3+磷光体的初始亮度,Pr3+或Ce3+在其中起到增加陷阱密度,提高发光亮度的作用。     

H2O2处理H3PW12O40/ZrO2-WO3光催化降解有机染料

采用浸渍法将H3PW12O40负载在ZrO2-WO3上,通过H2O2溶液的敏化,制得H3PW12O40/ZrO2-WO3(x)光催化剂。然后以光降解甲基橙为探针反应,对各反应影响因素进行了探究。在甲基橙初始质量浓度为5 mg/L,溶液pH=2.5,催化剂用量为0.3 g的优化条件下,光降解2 h,甲基橙的降解率达到91.2%,光催化降解甲基橙溶液为一级动力学反应。且H3PW12O40/ZrO2-WO3(x)对罗丹明B、碱性品红和和亚甲基蓝也具有较高的光催化活性,降解率分别为70.0%、73.0%和73.5%。     

三元体系Li+,K+//borate-H2O348K相平衡研究

采用等温溶解平衡法研究了三元体系Li+,K+∥borate-H2O在348 K时的相关系及密度、折光率、pH等平衡液相的物化性质。根据实验数据绘制了该三元体系的稳定相图以及物化性质-组成图。研究发现,该三元体系为简单共饱型,无复盐或固溶体形成。该体系稳定相图由一个三元共饱点、2条单变量曲线和2个结晶相区组成,结晶相区对应的平衡固相分别为Li2B4O7.3H2O和K2B4O7.4H2O。K2B4O7对Li2B4O7有盐溶作用。液相物化性质均随着K2B4O7质量分数的变化呈现规律性变化,在单变量曲线AE上随K2B4O7浓度的增大而增大,在单变量曲线BE上随K2B4O7浓度的增大而减小,共饱点E处达到最大值。