煆烧温度对BiOX(X=Cl,Br)的微观结构和光催化活性的影响（英文）

采用简单水解法和后热处理制备一系列BiOX(X=Cl,Br)光催化剂,通过XRD、拉曼、SEM、DSC-TGA、BET和UV-Vis表征所获得的样品,并且通过在模拟太阳光源下光催化降解甲基橙(MO)来评价煅烧温度对样品活性的影响。结果表明,催化剂的相结构、晶粒尺寸、形貌、比表面积、多孔结构和吸收带边缘均与焙烧温度有关。BiOBr在600℃已完全转变为Bi₂₄O₃₁Br₁₀,并在800℃开始转变为Bi₂O₃;而BiOCl在600℃才开始转变为Bi₂₄O₃₁Cl₁₀,在800℃全部转化为Bi₂₄O₃₁Cl₁₀。BiOCl的光催化活性随温度的升高而降低,这归因于比表面积和孔径的减小;而BiOBr的光催化活性先升高后降低,这与其良好的结晶和三维结构有关。     

Electrochemical performances and structure characteristic of LiMn2O4-xYx（Y=F, Cl, Br） compounds

Spinel LiMn2 O4-x Yx (Y=F, Cl, Br) compounds were prepared by solid-state reaction and the electrochemically galvanostatic charge-discharge cycles were performed using as-prepared compounds as cathode material. The influence of halogens on their lattice constants and the relation of electrochemical properties and their lattice constants were investigated. It is concluded that when the lattice constants are smaller than that of LiMn2O4, the reversible capacity fade is suppressed and the initial capacity sacrifice is observed. When the content of fluorine is 0.05, the lattice constant of LiMn2O3.95 F0.05 is larger than that of LiMn2O4, the initial capacity is improved. An efficient method was found to control the lattice constants of LiMn2O4 through the addition of halogen, and to improve the electrochemical performance of LiMn2O4. The LiMn2O3.95 F0.05 shows excellent electrochemical charge-discharge performance, with high initial capacity of 143 mAh/g and nearly no capacity loss after 116 cycles.     

Preparation, Characterization and Photocatalytic Property of Cubic α-Fe2O3 Nanoparticles

设计了一种简单的水热合成法合成晶型可控的立方结构的α-Fe2O3,通过扫描电子显微镜,透射电子显微镜,和X射线衍射对所制备产物的结构和形态特征进行了分析。制备的立方结构的α-Fe2O3的尺寸范围在130~150 nm之间。研究结果表明,α-Fe2O3纳米材料作为一种有效的光催化剂,在过氧化氢存在的条件下可以用来光催化降解废水中的有机物（如罗丹明B）,这为设计和开发高效率可见光催化剂在去除工业废水中有机染料的应用提供了新的探索和基础。     

Photocatalytic activity of ANbO3 （A=Li, Na, K）

1　INTRODUCTIONBecausetheamountofcoal,petroleumandotherfossilfuelusednowdaysincreases ,theirstoragede creasesanddepletionisinevitable .Itisurgenttofindoutrenewalenergywhichisindependentonpetroleum ,coalandotherfossilfuel.Hydrogenisasecondaryenergytoovercomeenergycrisis .Thepho tocatalyticsplittingofwaterusingoxidesemiconduc tormaterialsundersolarenergyisanidealroutetogeneratehydrogen .Inthepastseveraldecades ,muchprogress[110 ] hasbeenmadeinthewater photo catalyticcleavageusingTiO2 [11] …     

Adsorption properties of Ag（Ⅰ）, Au（Ⅲ）, Pd（Ⅱ） and Pt（Ⅳ） ions on commercial 717 anion-exchange resin

The adsorption properties of the four precious metal ions (Ag(I), Au(II), Pd(III) and Pt(IV)) on the commercial Cl^?-form 717 strongly basic anion-exchange resin were studied in detail. The effects of the contact time, solution acidity, and concentrations of Cl^? and Pb²⁺ ions on the adsorption properties were studied by the batch method. Then, the column method was conducted under the optimized adsorption conditions (pH=3.0). The effects of the sample loading flow rate and the length-to-diameter ratios of the columns were investigated. The precious metal ions adsorbed could not be eluted completely after the saturated adsorption because the precious metal ions were found to be reduced to their metallic states during the adsorption process. So, it is recommended that the commercial Cl^?-form 717 strongly basic anion-exchange resin should be decomposed directly to recovery the precious metals after the saturated adsorption.     

The unusual properties of the κ-phases ET2[N(CN)2]X (X = Cl,Br, I): a result of critical Coulomb interactions

A review is given of the astonishingly different physical properties of the above-mentioned three isostructural compounds (ET = bis(ethylenedithio)tetrathiafulvalene). While the Cl crystal is an insulator with ferrimagnetic order at low temperatures, turning into a re-entrant superconductor at a pressure of only 300 bar, the Br crystal is an inhomogeneous superconductor with coexisting magnetically ordered (and presumably insulating) domains. The I crystal is semimetallic, and its magnetic properties are not yet known. We focus on the possibility that the conduction electron system in these crystals is in the immediate vicinity of a Mott transition due to critical Coulomb interactions. Small changes in intermolecular distances, such as those caused by thermal expansion and especially by a lattice-dynamical second-order distortive transition can decide between a metallic (superconducting) and non-metallic (magnetic) ground state.     

Preparation and characterization of （metal, nitrogen）-codoped TiO2 by TiCl4 sol-gel auto-igniting synthesis

The nitrogen-doped and （metal, nitrogen）-codoped TiO2 photocatalysts （metal = Ag, Ce, Fe, La） were synthesized by sol-gel auto-igniting synthesis （SAS） with the complex compound sol of TiCl4-NH4NO3-citri acid-metal nitrate- NH3.H20 as a precursor. The products were characterized by means of XRD, XPS, and UV-Vis diffuse reflectance spectra, and their photocatalytic activity was investigated under visible light. It was found that all the synthesized powders showed good absorption for visible light, and that the radius and alterable valence states of doping metallic cations played important roles on their photocatalytic activity. These results were discussed in detail.     

Densities of molten Ni-（Cr,Co, W） superalloys

In order to obtain more accurate density for molten Ni-（Cr, Co, W） binary alloy, the densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys were measured with a sessile drop method. It is found that the measured densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys decrease with increasing temperature in the experimental temperature range. The density of alloys increases with increasing W and Co concentrations while it decreases with increasing Cr concentration in the alloy at 1 773-1 873 K. The molar volume of Ni-based alloys increases with increasing W concentration while it decreases with increasing Co concentration. The effect of Cr concentration on the molar volume of the alloy is little in the studied concentration range. The accommodation among atomic species was analyzed. The deviation of molar volume from ideal mixing shows an ideal mixing of Ni-（Cr, Co, W） binary alloys.     

Thermoelectric properties of MxMo6Te8 （M=Ag, Cu）

Ag and Cu filled Chevrel phase MxMo6Te8 (x=1.0, 2.0) samples were synthesized by direct solid state reaction and spark plasma sintering. The electrical and thermal properties were investigated in the temperature range of 300-800 K. The results show that both the electrical and thermal properties are affected by filler atoms. Although the electrical conductivity of MxMo6Te8 is slightly higher than that of state-of-the-art thermoelectric material, such as filled skutterudites, the absolute value of Seebeck coefficient is relatively low. Due to the phonon scattering by the filler atoms, the decrease of the thermal conductivity and the lattice thermal conductivity is obvious. As a result, the dimensionless figure of merit(ZT) is improved over the whole temperature region. The highest ZT value is 0.034 at 800 K for the AgMo6Te8 sample.     

Effect of calcination temperature on microstructure and photocatalytic activity of BiOX (X=Cl,Br)

A series of BiOX (X=Cl, Br) were prepared by simple hydrolysis and then calcined at various temperatures and they were characterized by XRD, Raman, SEM, DSC–TGA, BET and UV–Vis. The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) solution under simulated solar light irradiation. The results show that the phase structure, crystallite size, morphology, specific surface area, porous structure, and the absorption band-edges are related to the calcination temperature. For BiOBr, it has completely transformed to Bi₂₄O₃₁Br₁₀ at 600 °C and begins to transform to Bi₂O₃ at 800 °C. As for BiOCl, it begins to transform to Bi₂₄O₃₁Cl₁₀ at 600 °C and completely transforms to Bi₂₄O₃₁Cl₁₀ at 800 °C. Finally, the photocatalytic activity of BiOCl decreases with the temperature increasing owing to decrease of the specific surface areas and pore size, while the photocatalytic activity of BiOBr increases in the first stage and then decreases, which is related to good crystallization and three-dimensional structure.     

X-TiO2(X=Ce,Bi)粉体的光电催化性能的研究

采用溶胶-凝胶法制备出纳米X- TiO2(X=Ce,Bi)粉体,并用XRD、UV-Vis DRS对其进行表征,以500W氙灯模拟太阳光,考察改性TiO2粉体的可见光催化活性.采用涂覆法制备出改性TiO2电极,以300W高压汞灯为侧光源,考察了电极的光电催化性能.实验结果表明:改性TiO2粉体均为锐钛矿型晶相,Ce和Bi的加入不同程度地提高了TiO2在可见光区的吸光强度,Bi和Ce最佳摩尔掺杂量均为0.04％.3种电极光电催化性能先后排序为:TiO2电极＜0.04％Bi-TiO2电极＜0.04％Ce-TiO2电极,循环伏安曲线分析表明,金属离子的掺杂提高了TiO2电极的电催化活性,且Ce的掺杂对电极电催化活性的影响大于Bi.HPLC分析表明,金属离子掺杂使得苯环开环加速,促进了苯酚的氧化过程.     

Comparison of the spectroscopic behaviour of single crystals of lanthanide halides (X = Cl, Br)

Halides belong to large band gap matrices that have the perspective of wide applications when doped by optical active ions. This paper presents the results of spectroscopic studies of single crystals of halides (Cl, Br) of Ce, Pr and Nd. Their spectroscopic behaviour: electron–phonon coupling, ion pair interactions and the effect of covalency, is compared. Absorption, emission and emission excitation spectra of single crystals of LnCl₃·yH₂O (Ln = Nd, Pr, Ce; y=6, 7) were recorded at room temperatures and low temperatures down to 4.2 K. The intensities of the electronic lines and the Judd–Ofelt parameters were calculated (Nd, Pr) and compared to those of LnBr₃·yH₂O presented earlier by us. The relationship between the hypersensitivity and covalency was discussed. With increasing soft character of the halides (Br⁻ > Cl⁻), the covalent character of Ln–ligand bond increases and the hypersensitive bands become more intense. The Judd–Ofelt intensity analysis resulted in a set of τ_λ parameters evaluated with quite low standard deviations. The temperature dependences of the intensities have been found and the vibronic coupling in the f–f transitions were analysed. At the low temperature (4.2 K), strong vibronic components occur in the electronic lines of the Nd(III) and Pr(III) ions, mainly with the Ln–X vibrations. The modes, which are in resonance with the splitting of the ground state multiplet, mediate in the cooperative transitions.

Vibrational studies of the compounds under test were performed at the ambient temperature using IR and Raman spectroscopy. The assignment of the bands was done on the basis of the factor group analysis. The spectral features below 300 cm⁻¹ point at the differences between the spectra of the bromides and chlorides of Nd and Pr. Although the spectral features within the FIR region are complex, the bands of the praseodymium monocrystals originated by halogen bridges are clearly visible.     

MCr2O4(M=Co, Zn)纳米晶的合成及磁性

通过配合物热分解法制备MCr2O4(M=Co,Zn)纳米晶,并对其物相、表面微结构和磁性进行表征。结果表明,产物为直径40 nm左右的球形粒子,具有立方晶系尖晶石结构。磁滞回线表明,CoCr2O4在低温下表现出明显的亚铁磁性和较强的交换偏置场,矫顽力和交换偏置场分别为Hc=6.05×105A/m和He=1.93×104A/m,饱和磁化强度Ms和剩余磁化强度Mr分别为19.86和12.63 A.m2/kg,这可用CoCr2O4纳米晶的表面结构缺陷导致表面原子的磁结构自旋无序来解释。     

La5M3X (M=Sn,Bi; X=Cl,Br, I): exploring the limit of the Mn5Si3-type hosting lattice

Three new compounds add to the family of the Mn₅Si₃ type host–guest lattice. These are La₅Sn₃X (X=Cl, Br, I) synthesized from stoichiometric mixtures of La, LaX₃ and Sn heated under Ar atmosphere in sealed Ta ampoules at 850–990 °C for 13–62 days. La₅Sn₃X crystallize in the space group P6₃/mcm (No. 193) with lattice parameters a=9.603(1) Å, 9.637(1) Å and 9.673(1) Å; c=6.890(1) Å, 6.931(1) Å and 6.987(1) Å, respectively, for X=Cl, Br and I. Computational analysis using both the extended Hückel and the local density functional methods showed that the Sn and La site acts as electron reservoir, providing electrons to the interstitials as necessary. This gives rise to a metallic behavior. Susceptibility and conductivity measurements confirmed these predictions. The single crystal structure of La₅Bi₃Br is also reported.     

(Na1-yMy)1.6 Co2O4(M=K,Ca,Sr)的制备及电学性能

用溶胶凝胶法制备了NaCo2O4及(Na1-yMy)1.6Co2O4(M=K,0.05≤y≤0.35;M=Ca,Sr,0.10≤y≤0.40)的氧化物。研究结果表明:掺杂Ca、Sr的NaCo2O4样品的Seebeck系数都有一定提高;而掺杂K的NaCo2O4样品的Seebeck系数无明显提高,且掺K使NaCo2O4的功率因子降低;对NaCo2O4掺杂Ca的量0相似文献   

Charge-Transfer salts based on BET-TTF and the linear ions AuX2 (X = Br, I)

The organic π-electron donor E-bis(ethylenethio)-tetrathiafulvalene (BET-TTF) forms several charge-transfer salts with linear AuX₂⁻ (X = Br, I) counterions. Experimental conditions significantly affect the shape and the composition of the charge-transfer crystals. In fact, salts with different stoichiometries are obtained from each counterion. The magnetic behavior of the obtained salts have been studied by EPR spectroscopy. The EPR parameters (g, and ΔH_pp) of different mixed valence salts with the same counterion are very similar. The crystal structure of (BET-TIF)AuBr₂ has been determined by X-Ray diffraction: triclinic system, P-1, Z = l, a = 5.790(4)å, b = 7.786(3)å, c = 9.716(8)å = 75.11(5)°, β = 89.30(4)°, γ = 77.20(5)°, V = 395.5(5)å³. Single crystal electrical conductivity measurements of (BET-TTF)₂AuBr₂ show that this salt exhibits a semiconducting behavior with a σ(300) = 1.1 Scm⁻¹ and an energy gap of 0.14 eV.     

Bi^3＋—Cl^——H2O系热力学平衡

运用同时平衡原理和质量平衡原理对Ｂｉ＾３－Ｃｌ－Ｈ２Ｏ体系进行热力学分析和计算，在此基础上绘制了Ｂｉ＾３＋－Ｃｌ－Ｈ２Ｏ体系在２５℃下的各种涫淀物的平衡浓度对数－ＰＨ图，分析确定了各大相沉淀物稳定存在的ＰＨ。结果表明，溶液中铋离子和硝酸根离子的浓度及溶液的ＰＨ值是影响各固相稳定存在的重要参数。由热力学图得出，可以直接从溶液中沉淀的Ｂｉ２Ｏ３，要得到高纯工的ＢｉＯＣｌ必须严格控制溶液的ＰＨ范围。     

Preparation and electrochemical properties of LiMn1.95M0.05O4 （M=Cr, Ni）

The preparation process and electrochemical properties of LiMn2O4 and LiMnl.95M0.05O4 （M = Cr, Ni） were studied. The results show that the decomposition temperature range of xerogel prepared with lithium acetate and manganese acetate as raw rnaterials is large and the decomposition speed is slow. Oxygen consumed is apt to get a prompt supplement during the preparation of LiMn2O4, and carbonization of the organic matter can be reduced or avoided, which is favorable to the combination of lithium and manganese. Using lithium acetate, manganese acetate, chromium nitrate, and nickel nitrate as raw materials and adopting the citric acid complexing method, it has been found that the prepared powders have high purity, high quality stability, and even doping characters. With the increase of sintering temperature, the particle size and crystal lattice constant of LiMn1.95M0.05O4 （M = Cr, Ni） enhance. However, the purity of the product is relatively high and has no obvious change, which is advantageous to the control of the quality of LiMn1.95M0.0504 （M = Cr, Ni）. Doping with a small amount of Cr3. and Ni^2＋ can stabilize the spinel structure of LiMn2O4, suppress the Jahn-Teller effect, and improve the cycling properties but reduce the initial capacity.