BaAl2Si2O8∶Eu3+荧光粉的制备及发光性能

利用高温固相法制备Eu3+掺杂的BaAl2Si2O8荧光粉并研究其发光性能,通过X射线衍射分析该发光材料的结构特征.光致发光谱表明:在近紫外光激发下该荧光粉可以发出较好的红光,峰值位于615nm处;Eu3+的最佳掺杂量为0.08mol.分析了BaAl2Si2O8∶0.08Eu3+材料的发射强度随电荷补偿剂Li+,Na+...     

弱还原固相法制备BaAl2O4∶Eu2+荧光粉与发光性质研究

采用弱还原固相法制备了稀土Eu2+掺杂的BaAl2O4蓝绿色发光样品.采用XRD和荧光光谱对所制备的样品进行晶体结构与发光性能分析.XRD表明,BaAl2O4∶Eu2+样品为六方晶体结构.样品的激光光谱和发射光谱均为宽带谱,且发射光谱的最大峰值位于500 nm左右,属于Eu2+的4f65d→4f7跃迁,所发光正是人眼感觉舒适的蓝绿光.研究表明,当Eu2+掺杂量为5mol％时,蓝绿荧光粉BaAl2O4∶Eu2+的发光强度最好.     

Plasma-electrochemical synthesis of europium doped cerium oxide nanoparticles

In the present study,a plasma-electrochemical method was demonstrated for the synthesis of europium doped ceria nanoparticles.Ce(NO3)3· 6H2O and Eu(NO3)3·5H2O were used as the starting materials and being dissolved in the distilled water as the electrolyte solution.The plasma-liquid interaction process was in-situ investigated by an optical emission spectroscopy,and the obtained products were characterized by complementary analytical methods.Results showed that crystalline cubic CeO2:Eu3+ nanoparticles were successfully obtained,with a particle size in the range from 30 to 60 nm.The crystal structure didn't change during the calcination at a temperature from 400℃ to 1000℃,with the average erystallite size being estimated to be 52 nm at 1000℃.Eu3+ ions were shown to be effectively and uniformly doped into the CeO2 lattices.As a result,the obtained nanophosphors emit apparent red color under the UV irradiation,which can be easily observed by naked eye.The photoluminescence spectrum further proves the downshift behavior of the obtained products,where characteristic 5Do → 7F1,2,3 transitions of Eu3+ ions had been detected.Due to the simple,flexible and environmental friendly process,this plasma-electrochemical method should have great potential for the synthesis of a series of nanophosphors,especially for bio-application purpose.     

Self-assembled bright luminescent hierarchical materials from a tripodal benzoate antenna and heptadentate Eu(III) and Tb(III) cyclen complexes

The europium heptadentate coordinatively unsaturated (Eu(III)) and the terbium (Tb(III)) 1,4,7,10-tetraazacyclododecane (cyclen) complexes 1 and 2 were used in conjunction with ligand 3 (1,3,5-benzene-trisethynylbenzoate) to form the supramolecular self-assembly structures 4 and 5;this being investigated in both the solid and the solution state. The resulting self-assemblies gave rise to metal centered emission (both in the solid and solution) upon excitation of 3, confirming its role as a sensitizing antenna. Drop-cased examples of ligand 3, and the solid forms of 4 and 5, formed from both organic and mixture of organic-aqueous solutions, were analyzed using Scanning Electron Microscopy, which showed significant changes in morphology;the ligand giving rise to one dimensional structures, while both 4 and 5 formed amorphous materials that were highly dense solid networks containing nanoporous features. The surface area (216 and 119 m2·g^-1 for 4 and 5 respectively) and the ability of these porous materials to capture and store gases such as N2 investigated at 77 K. The self-assembly formation was also investigated in diluted solution by monitoring the various photophysical properties of 3–5. This demonstrated that the most stable structures were that consisting of a single antennae 3 and three complexes of 1 or 2 (e.g., 4 and 5) in solution. By monitoring the excited state lifetimes of the Eu(III) and Tb(III) ions in H2O and D2O respectively, we showed that their hydration states (the q-value) changed from -2 to 0, upon formation of the assemblies, indicating that the three benzoates of 3 coordinated directly to the each of the three lanthanide centers. Finally we demonstrate that this hierarchically porous materials can be used for the sensing of organic solvents as the emission is highly depended on the solvent environment;the lanthanide emission being quenched in the presence of acetonitrile and THF, but greatly enhanced in the presence of methanol.     

25℃下Na+,K+,Mg2+//Cl-,NO-3-H2O五元体系液固相平衡

The solubilities of the quinary system Na + ,K + ,Mg 2+ //Cl ,NO 3 -H2O and its two quaternary subsystems, Na + ,K + ,Mg 2+ //NO 3 -H2O and K + ,Mg 2+ //Cl ,NO 3 -H2O,were studied by isothermal method at 25°C and their phase diagrams were plotted.In the equilibrium phase diagram of quaternary system Na + ,K + ,Mg 2+ //NO 3 -H2O, there are one invariant point,three univariant curves and three regions of crystallization with one salt:NaNO3, KNO3 and Mg(NO3)2·6H2O.In the equilibrium phase diagram of quaternary system K + ,Mg 2+ //Cl ,NO 3 -H2O,there are three invariant points,seven univariant curves and five regions of crystallization with one salt:KNO3,KCl, Mg(NO3)2·6H2O,MgCl2·6H2O and KCl·MgCl2·6H2O.In the equilibrium phase diagram of the quinary system Na + , K + ,Mg 2+ //Cl ,NO 3 -H2O,there are four invariant points,and seven regions of crystallization with one salt:NaCl, KCl,NaNO3,KCl·MgCl2·6H2O,KNO3,MgCl2·6H2O and Mg(NO3)2·6H2O.     

Effect of Nano-Al2O3 on Mechanical Properties and Microstructure of Si3N4 Ceramics

Si3N4ceramics were prepared by pressureless sintering at 1 650 ℃ in nitrogen atmosphere using Si3N4powder as main starting material and adding nanoAl2O3powder( 3%,6%,9%,12%,and 15% in mass,the same hereinafter). The bending strength and fracture toughness( KIC) of the specimens were detected.The microstructure and phase compositions of the specimens were analyzed. The results show that Si3N4ceramics can be prepared by pressureless sintering when adding9%- 12% nano-Al2O3as active reactant,which dissolves in Si3N4,in-situ forming non-oxide SiAlON. The obtained Si3N4ceramics have the maximum bending strength of 710. 86 MPa and KICof 8. 61 MPa·m1 /2.The excellent properties come from many interwoven structures distributed uniformly in the ceramics matrix,which is composed of big and firm plate-like β-Si3N4,hexagonal SiAlON and sheet Si2N2O.     

High-temperature Reaction of Silica Fume-Si_3N_4 System

The specimens were prepared by molding the mixture of silica fume(w(SiO2)=94.5%;average particle size:0.08 μm) and silicon nitride(≤0.074 mm) with a mass ratio of 11,carbon embedded firing at 1 300 ℃,1 450 ℃,1 500 ℃,1 550 ℃ and 1 600 ℃ for 3 h in air,and then water-cooling,respectively.The microstructure and phase composition of the specimens were analyzed.The results show that:(1) silica fume reacts obviously with Si3N4 forming Si2N2O above 1 550 ℃.The edges and corners of Si3N4 grains become smooth and th...     

Effects of Precursors for Preparing Intermediate Layer on the Performance of Ti/SnO2+Sb2O3/PbO2 Anode

The Ti/SnO2+Sb2O3/PbO2 anode with SnO2+Sb2O3 intermediate layer obtained by the polymeric precursor method (PPM) and with the conventional route was studied. The morphology and microstructure of SnO2+Sb2O3 intermediate layer derived from different precursors and the top PbO2 active layer were examined by means of ESEM and XRD. The lifetime and electrocatalytic activity of the anode were also assessed by the cyclic voltammetry and accelerated lifetime test in 1.0 mol/L H2SO4 solution. It was found that precursor solvents affected lifetime, microstructure and morphology of the anode, and had little influence on electrocatalysis activity of the electrodes. The accelerated lifetime of Ti/SnO2+Sb2O3/PbO2 anode with intermediate layer prepared by PPM was 29.5 h in 1.0 mol/L H2SO4 solution, which was respectively about four times and twice that of the anode prepared with ethylene glycol and ethanol. After the anode was subjected to thermal corrosion, the lifetime still reached 27 h in contrast to the others.     

Influences of Al and Si Powders on Microstructure and Hot Mechanical Properties of Al2O3-C Slide Plates

The basic formulation of Al2O3- C slide plates was65%( in mass,the same hereinafter) white fused corundum particles,25% white fused corundum fines,6% active α-Al2O3 micropowder,4% carbon black and flake graphite, and additional 4% phenolic resin.Based on this formulation,3% Al powder,3% Si powder,and 3% Al + 3% Si powder were used to substitute equivalent white corundum fines to improve the hot mechanical properties of Al2O3- C slide plates. The specimens with dimensions of 140 mm × 25 mm × 25 mm were pressed at 150 MPa,dried at 200 ℃ for 24 h,and hot treated at 1 400 ℃ for 3 h in carbon embedded condition. Then hot modulus of rupture and thermal shock resistance of the specimens were tested and the phase compositions and microstructure were analyzed. The results show that specimen with 3% Al powder has the higher hot modulus of rupture but lower residual modulus of rupture after thermal shock than the specimen with3% Si powder; the specimen with 3% Al + 3% Si powders exhibits the highest hot modulus of rupture and the best thermal shock resistance; the change of mechanical property is closely related with the in-situ formed nonoxides: AlN in the form of bars is formed in specimens with Al powder; fibrous SiC whiskers are formed in specimens with Si powder; in the specimens with both Al and Sipowders,besides AlN and SiC whiskers,hexagonal tabular SiAlON is in-situ synthesized,which interlocks with each other.     

P507溶于煤油作为载体的一种新型分散组合液膜对Eu3+的分离

The separation of Eu3+ is studied with a dispersion combined liquid membrane (DCLM), in which polyvinylidene fluoride membrane (PVDF) is used as the liquid membrane support, dispersion solution containing HCl solution as the stripping solution, and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (P507) dissolved in kerosene as the membrane solution. The effects of pH value, initial concentration of Eu3+ and different ionic strength in the feed phase, volume ratio of membrane solution to stripping solution, concentration of HCl solution, concentration of carrier, different stripping agents in the dispersion phase on the separation are investigated. The optimum condition for separation of Eu3+ is that concentration of HCl solution is 4.0 mol•L1, concentration of carrier is 0.16 mol•L1, and volume ratio of membrane solution to stripping solution is 30︰30 in the dispersion phase, and pH value is 4.2 in the feed phase. The ionic strength has no significant effect on separation of Eu3+. Under the optimum condition, when the initial concentration of Eu3+ is 0.8×104 mol•L1, the separation percentage of Eu3+ is 95.3% during the separation time of 130 min. The kinetic equation is developed in terms of the law of mass diffusion and the theory of interface chemistry. The diffusion coefficient of Eu3+ in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and their values are 1.48×107 m2•s1 and 36.6 μm, respectively. The results obtained are in good agreement with literature data.     

新型香豆素系荧光染料

Seven novel fluorescent coumarin derivatives were synthesized from 7-diethylamino-4-chloro-3-formyl-coumarin. The spectra of absorption, excitation and emission were dependent not only on the structures and also on the concentration of dyes. The PPP-IVIO predictions can only be consistent with the spectra in dilute solutions.     

Solubility measurement and prediction of phase equilibria in the quaternary system LiCl + NaCl + KCl + H_2O and ternary subsystem LiCl+ NaCl + H_2O at 288.15 K

Using isothermal dissolution method, the phase equilibrium relationship in quaternary system LiCl + NaCl + KCl+ H_2O and the ternary subsystem LiCl + NaCl + H_2O at 288.15 K were investigated. Each phase diagram of two systems was drawn. The phase diagram of LiCl + NaCl + H_2O system contains two solid phase regions of crystallization LiCl·2H_2O and NaCl. In the phase diagram of LiCl + NaCl + KCl + H_2O system, there are three crystallization regions: LiCl·2H_2O, NaCl and KCl respectively. In this paper, the solubilities of phase equilibria in two systems were calculated by Pitzer's model at 288.15 K. The predicted phase diagrams generally agree with the experimental phase diagrams.     

V2O5-WO3-MoO3/TiO2催化剂用于NH3选择性还原减排NOx的性能（英文）

The V2O5-WO3-MoO3/TiO2 honeycomb catalyst was prepared with industrial grade chemicals. The structural and physico-chemical properties were analyzed with X-ray diffraction (XRD), scanning electron micrograph (SEM) and mercury porosimetry. The NOx conversion and durability were investigated on a pilot plant test set under the actual operational conditions of a coal fired boiler. The catalyst monolith had good formability with mass percentage of V:W:Mo:TiO2 :fiber glass= 1:4.5:4.5:72:18. Vanadium, tungsten and molybdenum species were highly dispersed on anatase TiO2 without causing the transformation of anatase TiO2 to rutile by calcining under a current of air at 450℃ for 4.5 h, but there were some degrees of crystal distortion. The catalyst particle sizes were almost uniform with close pile-up and the pore structure was regular with complete macro-pore formation and large specific surface area. The NOx conversion was sensitive to temperature but nearly insensitive to NH3 . The catalyst showed strong adaptability to NOx concentration with activity above 80% in the range of 615-1640 mg·m-3 . Within the range of 720-8640 h continuous operation, the NOx conversion dropped at a rate of about 1% reduction per 600 h.     

Kinetic Study of Co-b-Zeolite for Selective Catalytic Reduction

The effects of grain size, space velocity, temperature and reactant concentration on the kinetics of NOx reduction with propane over Co-b-zeolite catalyst were investigated. The external mass transfer phenomenon was examined by varying the space velocity. The results show that the transfer can be negligible when the space velocity is greater than 60000 h-1 in low temperature range. However, the transfer exists at high temperatures even when the space velocity reaches a high level. Variation of the catalyst grain size from 0.05 to 0.125 mm does not change the conversion rate of NOx. The concentrations of components, NOx, C3H8 and O2, were also investigated to have a better understanding of mechanism. Based on the experimental data, the selectivity formula was proposed. The results shows that lower temperature is helpful to get higher selectivity as the activation energy of hydrocarbon oxidation, Ea,2, is greater than that of NOx reduction, Ea,1, (Ea,2>Ea,1). High NOx concentration and low C3H8 concentration are beneficial to high selectivity. However in order to maintain high activity simultaneously, the temperature and C3H8 concentration should be high enough to promote NOx reduction. 10%(j) H2O and 75′10-6(j) SO2 were introduced into the reaction system, and Co-b-zeolite shows strong resistance to water and SO2.     

填料塔中碳酸钾/哌嗪混合吸收液脱除CO2的体积传质系数

The process of removing dilute CO2 from air by using me mixtures of K2CO3 and piperazine (PZ) was conducted in a random packed tower at 25℃. The results showed that PZ increased the absorption rate of CO2 into aqueous K2 CO3 much more effectively than MEA or DEA. The volumetric overall mass transfer coefficient (KGa) of dilute CO2 absorption into K2CO3/PZ was measured. The KGa value was evaluated over the ranges of main operating variables: the concentration of CO2 in inlet gas, gas flow rate, liquid loading, CO2 loading in liquid phase, and the concentrations of K2CO3 and PZ. The test showed that KGa could be remarkably improved by increasing liquid loading and the concentration of PZ, and decreasing the concentration of CO2 in inlet gas, as well as the gas flow rate and CO2 loading in liquid phase.     

模拟城市垃圾焚烧中硫化合物对重金属Cd迁移分布的影响

The effect of sulfur compounds （including sulfur, sulfide, sulfite and sulfate）, initial concentration of heavy metal and operating conditions on Cd emission in municipal solid waste （MSW） incineration were investi-gated using a simulated tubular furnace and simulated MSW spiked with Cd. The concentration of Cd was meas-ured by inductively coupled plasma-atomic emission spectrometry （ICP-AES） after digesting the samples including bottom ash, fly ash and flue gas according to related USEPA methods. The results show that S and Na2S tend to in- crease Cd partitioning in bottom ash, whereas Na2SO3 and Na2SO4 tend to reduce Cd partitioning in bottom ash. The effect of sulfur compounds on Cd partitioning in bottom ash was in the sequence of Na2S〉S〉Na2SO3〉 Na2SO4. chemical equilibrium analysis is also performed to determine the effect of sorbents on Cd adsorption. The calculations show that S presents strong affinity for Cd and restrains Cd adsorption by SiO2, whereas when temperature rises to between 830℃ and 1030℃, Cd adsorption efficiency of SiO2 is over 80% and the efficiency of Al2O3 is up to 85%.     

白光LED用红色发光粉La_(9.33)(SiO_4)_6O_2:Eu~(3+)的制备和发光特性

采用高温固相法合成具有磷灰石结构的La9.33(Si O4)6O2:Eu3+红色荧光粉。该荧光粉的性质通过X射线粉末衍射、荧光光谱来表征。La9.33(Si O4)6O2:Eu3+的激发光谱主要由以285 nm为中心的宽谱峰以及一系列由Eu3+离子f-f跃迁的锐线峰组成,在近紫外区有一个最强的激发峰在393 nm。在393 nm激发下,可以观察到La9.33(Si O4)6O2:Eu3+在612 nm处产生强烈的红光。发光特性表明,La9.33(Si O4)6O2:Eu3+荧光粉可能成为潜在近紫外芯片用红色荧光粉。     

One step synthesis and characterization of copper doped sulfated titania and its enhanced photocatalytic activity in visible light by degradation of methyl orange

This paper reports on the synthesis of copper doped sulfated titania nano-crystalline powders with varying(2.0%–10.0%, by mass) by single step sol gel method. The synthesized photo catalyst has been characterized by employing various techniques like X-ray Diffraction(XRD), Ultraviolet–Visible Diffuse Reflection Spectroscopy(UV–Vis DRS), X-ray Photoelectron Spectroscopy(XPS), Scanning Electron Microscopy(SEM), Energy Dispersive Spectrometry(EDS), Fourier Transform Infrared Spectroscopic Studies(FT-IR), and Transmission Electron Microscopy(TEM). From the XRD and TEM results, all the samples were reported in anatase phase with reduction in particle size in the range of 7 to 12 nm. SEM indicated the change in morphology of the particles. The presence of copper in titania lattice was evidenced by XPS. From UV–Vis DRS and FT-IR studies indicated that prominent absorption shift is observed towards visible region(red shift), the entry of Cu2+into Ti O2 lattice as a substitutional dopant and SO42-ions were covalently bonded with Ti4 +on the surface of the copper doped titania respectively.The photocatalytic activity studies were investigated by considering methyl orange(MO) as dye pollutant in the presence of the visible light. The effect of various parameters like effect of dosage of the catalyst, dopant concentration, p H of the solution, and concentration of the dye was studied in detail.     

Eu~(3+)激活的La_2(Mo,S)_2O_9粉体的结构及光致发光

用高温固相反应合成稀土Eu3+激活的La2Mo2-ySyO9(y=0～0.07)钼酸盐红色荧光粉,并表征样品的结构和光致发光特性。X射线衍射分析表明:少量S取代Mo进入晶格后,样品的结构没有发生明显改变,仍为β-La2Mo2O9立方相,但晶胞参数随S掺杂浓度的增加逐渐减小。光致发光测试表明:样品均显示Eu3+的红光特征发射(5D0→7F2),主发射峰位于615nm附近;以615nm为监测波长所得的激发光谱中,位于465nm对应于Eu3+的线谱跃迁(7F0→5D2)最强,尤其当掺杂少量S后,Eu3+的红光发射强度明显增加,可达到La2Mo2O9:Eu发光强度的2倍。     

溶剂热法制备一维锶磷灰石纳米棒及其发光性能研究(英文)

One-dimensional strontium hydroxyapatite(Sr-HAp) nanorods were successfully synthesized by a sim-ple solvothermal method.The products were characterized via X-ray diffraction(XRD),Fourier transform infrared(FT-IR),cold field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),photoluminescence(PL) excitation and emission spectra.The experimental results indicated that oleic acid as a surfactant played a key role in confining the growth of the Sr-HAp powders.A possible formation mechanism of the one-dimensional nanorod was proposed and elaborated.Moreover,the as-obtained Sr-HAp samples showed an in-tense and bright emission band centered at 460 nm under long-wavelength UV light excitation and the contents of NaOH used in the synthetic process had an obvious impact on the optical performance of Sr-HAp powders.The possible luminescent mechanism of the Sr-HAp samples was discussed.