溶胶-凝胶-微波法制备阴阳离子同时掺杂型LiAl_xMn_(2-x)O_yF_z

以LiNO3、Al(NO3)3·9H2O、LiF和MnNO3为原料,通过控制n(Li)/n(Mn)和Al、F掺杂量,溶胶-凝胶-微波法在750℃下合成阴阳离子复合掺杂型Li1.00Al0.05Mn1.95O3.95F0.05电极材料。XRD实验证明Li1.00Al0.05Mn1.95O3.95F0.05为纯尖晶石结构。掺杂适量的Al可以改善材料的循环性能,掺杂氟不但可以不降低材料的初始比容量而且可以显著降低材料在高温使用时的容量损失。Li1.00Al0.05Mn1.95O3.95F0.05在室温条件下的首次放电比容量达到115mAh/g,循环50次后放电比容量仍保持在109mAh/g,即使在55°C的高温,50次的总容量损失率也仅有10.1%。     

Preparation and Electrochemical Property of Li_（1.05）Co_（0.05）VxMn_（1.95-x）O_4 as Cathode Material for Lithium Ion Batteries

采用溶胶-凝胶法合成制备了分子式为Li1.05Co0.05VxMn1.95-xO4（x=0.02、0.05、0.08）的固溶体样品。利用XRD、SEM对材料进行结构形态表征,并以合成的材料为正极材料进行循环伏安（CV）和恒电流充放电测试,结果显示：固溶体Li1.05Co0.05VxMn1.95-xO4具有较好的尖晶石结构,且颗粒分布均匀,晶面光滑。电化学测试结果显示：其具有较好的充放电性能和良好的循环性能,在室温0.5 C充放电倍率下,Li1.05Co0.05V0.05Mn1.9O4材料的初始放电比容量为110.7 mAh/g,且50次循环后,容量保持率为94.6%。     

阴阳离子复合掺杂型Li_(1+x)Mn_(2-x)O_(4-y)F_y的合成机理研究

以LiNO3、LiF和醋酸锰为原料,采用柠檬酸络合法,通过控制原材料配比,在750℃下,制备出尖晶石型系列Li1+xMn2-xO4-yFy电极材料。运用等离子体发射光谱法和电位分析法相结合的分析手段测定材料的实际组成,通过分析试样的IR和XRD谱图参数、氟和锂掺杂量与锰的平均氧化数以及材料晶胞常数的变化关系,研究了氟的掺杂取代机理,并得出掺杂的氟取代λMnO2骨架中氧的结论;结合合成材料前驱体的TGA DTA谱图,阐述了Li1+xMn2-xO4-yFy的形成过程。     

Li_(1.02)Mn_(1.92)Al_(0.02)Cr_(0.02)Mg_(0.02)O_(4-x)F_x尖晶石正极材料的研究

采用溶胶-凝胶法合成了复合离子掺杂的尖晶石型锰酸锂Li1.02Mn1.92Al0.02Cr0.02Mg0.02O4-xFx(x=0,0.06)正极材料,并用XRD、CV、EIS和充放电测试等研究了其结构和电化学性能。结果表明,F与金属离子(Li、Al、Cr、Mg)的复合掺杂不仅提高了材料的比容量,还增加了尖晶石结构的稳定性,改善了材料的循环性能和可逆性能;充放电测试结果表明,Li1.02Mn1.92Al0.02Cr0.02Mg0.02O3.94F0.06具有优越的循环性能,常温下,以1/3C充放电的首次放电容量及50个循环后的容量保持率分别为117.9 mAh/g,96.9%。     

溶胶-凝胶-微波法制备Li_(1+x)Mn_2O_y

以LiNO3和MnNO3为原料,溶胶凝胶法制备前驱体后,利用微波加热法,在750℃条件下保温20min,合成了Li1+xMn2Oy。利用XRD和FTIR分析手段,研究了锂掺杂量对材料结构的影响,利用恒电流充放电法,研究了材料的电化学性质。XRD和FTIR实验说明,适量的锂离子掺杂不改变材料的立方尖晶石结构;充放电实验显示,Li1.04Mn2O4.056是比较理想的电极材料,其首次放电比容量达到118.6mAh/g,5次循环后的容量损失率也仅为1.9%。     

Mg2+、Zr4+离子掺杂对Li4Ti5O12电化学性能的影响

以固相反应法合成了尖晶石型Li4Ti5O12电极材料,进行了金属离子掺杂以提高其导电性及综合性能,以适应用于大电流充放电的目的。采用XRD、室温恒流充放电循环、交流阻抗和循环伏安等测试手段,考察了A位掺杂Mg(Li4-xMgxTi5O12,x=0.15),B位掺杂Zr(Li4ZrxTi5-xO12,x=0.15)对Li4Ti5O12结构和电化学性能的影响。结果表明:掺杂少量的Mg2+、Zr4+未引起材料结构的变化,明显降低了Li4Ti5O12电荷转移阻抗,使导电性得到有效提高。0.1 C放电倍率下放电,未掺杂及掺杂Mg2+、Zr4+的Li4Ti5O12首次放电容量分别为159.8、144.9、161.2mAh/g,循环40次后,容量分别保持为113.8、130.6、133.6 mAh/g。与未掺杂的Li4Ti5O12相比,掺杂后的电极材料极化减小、循环容量及稳定性提高。     

层状LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(1.95)Y_(0.05)(Y=O,F,Cl,Br)正极材料的合成及高温电化学性能研究

采用溶胶-凝胶法合成层状LiNi1/3Co1/3Mn1/3O1.95Y0.05(Y=O,F,Cl,Br)正极材料,在850℃空气氛围下煅烧20h得到晶型较好的正极材料。以XRD、SEM和充放电测试等手段对材料的晶体结构、表观形貌和电化学性能进行表征。XRD显示F-和Cl-掺杂材料具有高度有序的二维层状结构;充放电测试表明,掺杂F-和Cl-的材料放电比容量、循环性能和倍率性能均优于未掺杂材料,特别是掺杂F-材料在55℃,电压范围为2.0～4.6V,0.15mA电流下首次放电比容量高达207.5mAh/g,且0.9mA电流下第60次循环的容量仍达到165.1mAh/g。掺杂Br-的材料结构稳定性、循环性能和放电比容量均比未掺杂材料差。     

Li0.98Mn2O4的流变相法合成及电化学性能研究

用流变相反应法以乙酸锂、乙酸锰、柠檬酸为原料合成正极材料Li0.98Mn2O4,探讨了合成条件;经X-射线衍射表征,热重法(TG)和差热分析(DTA)以及电化学性能测试表明:Li0.98Mn2O4结晶性能很好,为尖晶石结构,其首次放电比容量高达130 mAh/g,具有较好的循环性,40次循环后还能保持初始容量的88%以上。     

四氧化三锰制备掺杂LiMn_2O_4及其性质研究

以Mn3O4、Li2CO3、Co3O4、Al2O3和NiCO_3为原料,固相法合成Co、Al、Ni掺杂LiMn_2O_4。采用X-射线衍射、扫描电子显微镜、恒电流充放电和电化学阻抗等技术研究合成材料的结构、形貌及电化学性能。结果表明:Co、Al、Ni掺杂没有改变LiMn_2O_4的晶体结构,但晶格常数略有减小。掺杂后LiMn_2O_4晶粒规整,表面光滑,晶粒形貌差别不大。掺杂后LiMn_2O_4的比容量有所下降,循环性能得到改善,容量保持率是Li Co0.05Mn1.95O4Li Ni0.05Mn1.95O4Li Al0.05Mn1.95O4LiMn_2O_4。Li Co0.05Mn1.95O4的循环性能最好。掺杂后LiMn_2O_4锂离子扩散系数有所提升,其中Li Co0.05Mn1.95O4的锂离子扩散系最大。     

改善镍锰基富锂层结构正极材料的电化学性能研究

作为正极材料,Li1. 2Ni0. 2Mn0. 6O2在低碳率下提供高放电容量,但在高碳率下提供低放电容量。充放电过程中存在较大的电位滞后,充放电曲线在充放电循环过程中发生变化。为了实现在高碳率和低碳率下的高放电容量,在高镍含量材料(Li/TM)中实现锂/过渡金属(Li/TM)比Li1. 2Ni0. 35Mn0. 45O2调整。结果表明:随着x的减小,放电容量先增大后减小,Li1. 2-xNi0. 35+(0. 35/0. 8) xMn0. 45+(0. 45/0. 8) xO2(x=0. 04),可以表示为Li1. 16Ni0. 37Mn0. 47O2,表现出最高的放电容量。据此,研究了锂离子电池的电化学性能Li1. 16Ni0. 37Mn0. 47O2与传统的富锂层结构正极材料,即Li1. 2Ni0. 2Mn0. 6O2。由此得出改变锂离子阴极材料成分的结论,Li1. 16Ni0. 37Mn0. 47O2缓解了富锂层状结构正极材料的低倍率性能、潜在迟滞、充放电曲线形状变化等缺点。     

Effects of calcination condition on expansion property of MgO-type expansive agent used in cement-based materials

Previous research indicated that the expansion property of MgO-type expansive agent (MEA) depended strongly on the calcining conditions, i.e. kiln temperature and residence time. However, the intrinsic effect of calcination condition on the expansion property of MEA has not been clearly demonstrated. In the present work, the effects of calcination condition on the microstructure, hydration activity, and expansion property of MEA have been investigated, and their correlations are also studied. Results indicate that the microstructure of MEA is the intrinsic factor that controlling its expansion property, which is influenced by the calcination condition. MEA produced under higher temperature and longer residence time has less interior pores, larger crystal size of MgO, and smaller specific surface area, thus resulting in lower hydration activity and slower expansion at early age, but larger “ultimate” expansion at late age. While, a new expansion model of MEA is proposed to explain these results.     

Toughening of polypropylene with styrene/ethylene‐butylene/styrene triblock copolymer: Effects of reactive and nonreactive compatibilization

The effects of the compatibilization on the toughening of polypropylene (PP) by melt blending with styrene/ethylene‐butylene/styrene triblock copolymer (SEBS) in a twin‐screw extruder were investigated. The compatibilizers used were an SEBS functionalized with maleic anhydride, a PP functionalized with acrylic acid, and a bifunctional compound, p‐phenylenediamine (PPD). The effects of the compatibilization were evaluated through the mechanical properties and by the determination of the phase morphology of the blends by scanning electron microscopy. Reactive compatibilized blends show up to a 30‐fold increase in impact strength compared to neat PP, which was likely to have been due to the reaction of the bifunctional compound (PPD) with the acid acrylic and maleic anhydride groups, which rendered both morphological and mechanical stability to these blends. The addition of the PPD to the blends significantly changed their phase morphologies, leading to larger dispersed particles' average diameters, probably due to the morphological stabilization at the initial processing steps during extrusion, with the occurrence of the chemical reactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1081–1094, 2003     

Material and environmental parameter effects on the leaching of cement pastes: Experiments and modelling

Results already published on the leaching of cement pastes have shown that the kinetics depends sensitively on the material and environment. However and because of the variability of the tested materials and leaching protocols, it is difficult to compare these data and quantify the effect of each parameter. In this paper, a large experimental database on the leaching kinetics of cement pastes is built. Four parameters are investigated: type of cement (portland cement, silica fume cement, slag cement, ternary cement with slag and fly ash); water-to-cement ratio (0.5; 0.4; 0.25), temperature (26 °C; 72 °C; 85 °C) and chemical composition of the leaching solution (pure water, mineralised water, ammonium nitrate solution). Firstly, the database is used to calculate the leaching kinetics of the cementitious materials. Secondly, a simplified model predicting the one-dimensional leaching kinetics for other water-to-cement ratios and temperature up to 85 °C is presented.     

(SrZrO_3)_(10)(SrTiO_3)_(90)缓冲层对PZT结晶及性能的影响

采用Sol-gel法制备了PbZr0.52Ti0.48O3 (PZT)薄膜,并研究了(SrZrO3)10(SrTiO3)90((SZO)10(STO)90)缓冲层对PZT薄膜结晶和性能的影响.X射线衍射(XRD)结果表明:(SZO)10(STO)90缓冲层对PZT薄膜结晶有取向诱导作用,由(SZO)10(STO)90诱导的PZT薄膜有很强的(111)择优取向,缓冲层将PZT薄膜的取向度α由45.0%提高到了90.1%以上;PZT的(111)择优取向提高了薄膜的电性能,使剩余极化强度Pr从26.8 μC/cm2增大到38.8 μC/cm2.     

Photocatalytic degradation of air pollutants — From modeling to large scale application

Indoor as well as outdoor air quality and their limiting values remain a major problem to our present-day society.This paper addresses the modeling of the decomposition process of nitrogen monoxide (NO) on reactive concrete surfaces under the controlled exposition of a UV source. Within this model the external mass transfer of the pollutant and the internal molecule diffusion-reaction were considered. A first-order kinetics equation is derived with respect to the NO concentration and a site-competitive adsorption between NO/NO₂ and water molecules, resulting in a dependence of the reaction kinetics on the relative humidity. Using the proposed model, a reaction rate constant k and an adsorption equilibrium constant K_d can be derived which describe an active paving stone accurately. Experimental results from a self-developed photoreactor with continuous flow mode were used to validate the proposed kinetic expression. Furthermore, the effect of variations in process conditions such as irradiance and relative humidity on the two constants k and K_d is investigated. All modeling work provides a sound foundation for the translation of this process to real outside conditions. In this regard an upcoming project in a Dutch city is described in brief.     

硫氰酸锰及其相关衍生物的合成及化学表征

合成了金属有机配合物非线性光学晶体硫氰酸汞锰，及其相关衍生物，二二甲亚砜合硫氰酸汞锰，乙二醇一甲醚合硫氰酸汞锰，二水合二N，N－二甲基乙酰胺合硫氰酸汞锰，二水合二N－甲基－α－吡咯烷酮合硫氰酸汞锰。采用元素分析，红外光谱以及紫外－可见－近红外透央求我谱分析对其进行了化学表征。     

Design and processing of ZnO doped tricalcium phosphate based materials: Influence of β/α polymorph phase assemblage on microstructural evolution

Tricalcium phosphate (TCP) based biomaterials are excellent candidates in hard tissue engineering due to their similarity to the natural bone composition and outstanding properties. The presence of additives such as (Mg²⁺, Zn ²⁺, F⁻, CO₃²⁻ and/or SiO₄⁻) in solid solution in the structure of TCP, affects the stability of its different polymorphs and therefore the properties of TCP based biomaterials. It is known that the incorporation of zinc in TCP in the non-toxic level stimulates bone growth and its mineralization, hence its interest. Nevertheless its effect on phase assemblage and microstructure evolution has not been clearly established. The main purpose of this study was to synthesize TCP and zinc doped monophasic/biphasic α/β-TCP dense biomaterials, by solid-state sintering process, with different ZnO contents and controlled phase proportions and microstructure on the final material. The effect of ZnO content and sintering temperature on phase assemblage, densification and microstructural evolution has been investigated.     

Optimizing multiple qualities in as‐spun polypropylene yarn by neural networks and genetic algorithms

This investigation considers a quantitative procedure for determining the values of critical process parameters in melt spinning to optimize the qualities of denier, tenacity, breaking elongation, and denier variance in as‐spun polypropylene yarn. An orthogonal array in the Taguchi method defines the minimum set of parameter‐level combinations that are experimentally tested. The significant process parameters, namely the third extruder barrel temperature, spinning temperature, metering pump speed, and take‐up velocity, are identified on the basis of the analysis of variance and F test. After a confirmation experiment is conducted to ensure the reproducibility of the experimental results, the back‐propagation neural network establishes a continuous system linking 10 process parameters and four qualities. The technique for order preference by similarity to an ideal solution can be used to obtain a performance measure for assessing multiple qualities. The genetic algorithm attempts to find parameter values for optimizing the quality performance, including the denier, tenacity, breaking elongation, and denier variance. Finally, the experimental results demonstrate that the smallest denier, largest tenacity, smallest breaking elongation, and second smallest denier variance of as‐spun polypropylene yarn can be achieved with the proposed approach in melt spinning. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2532–2541, 2006     

Selective plasma‐induced grafting of polystyrene onto polyolefin blends

Plasma pretreatment has been used to generate reactive radicals and oxygenated groups on polymer surfaces for graft polymerization. The polymer substrates studied were composed of a polypropylene–polyethylene (PP–PE) copolymer, which was predominantly PP, and also contained blended ethylene–propylene rubber (EPR) as either about 15 or about 60 mol %. A pure PP substrate was also studied for comparison. The grafted polymer was polystyrene (PS). Raman microspectroscopic 2‐dimensional mapping was used to elucidate the role of crystallinity and EPR in the plasma treatment and graft polymerization process. It was found that the plasma pretreatment favored the EPR component of the substrate and the graft yield was related to the EPR content. Crystallinity seemed to have a much less significant effect on the grafting reaction. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1643–1652, 2003     

二环戊二烯在脂环／芳香族环氧树脂中的应用

本文概述了以二环戊二烯及其衍生物为基础的脂环／芳香族环氧树树研究与开发近况；并介绍了这些树脂的主要特性及其在电子工业中的一些应用。