BaPbO3的生成及EXAFS研究

采用低Pb/Ba摩尔比及低的反应温度，以BaCO₃和PbO为原料，固相反应合成了BaPbO₃无机微粉。通过XRD分析，确定了不同Pb、Ba比例下生成的Ba-Pb-O化合物均为立方钙钛矿结构。首次采用EXAFS对BaPbO₃微粉中Pb原子的近邻结构进行了分析，分析了在立方钙钛矿BaPbO₃结构中，氧空位的存在是导致BaPbO₃具有类似金属导电性的主要原因。     

非化学计量组成Ba1.03Ce0.5Zr0.4La0.1O3－α的化学稳定性和离子导电性

用高温固相反应法合成了非化学计量组成的Ba_1.03Ce_0.5Zr_0.4La_0.1O_{3－α质子导体. 粉末X射线衍射(XRD)结果表明, 该材料为单一钙钛矿型BaCeO3斜方晶结构, 在高温下、CO2或水蒸气气氛中具有较高的稳定性. 扫描电子显微镜(SEM)观察分析表明, 材料经1550 ℃烧结20 h非常致密. 在500～900 ℃温度范围内, 用交流阻抗谱技术测定了材料在湿润氢气和湿润空气气氛中的电导率; 用气体浓差电池方法测定了材料在湿润氢气、湿润空气气氛中和氢-空气燃料电池条件下的离子迁移数, 研究了材料的离子导电特性, 并与化学计量组成的BaCe0.5Zr0.4La0.1O3－α材料进行了比较. 结果表明, 在500～900 ℃温度范围内、湿润氢气气氛中, Ba1.03Ce0.5Zr0.4La0.1O3－α材料的质子迁移数为1, 是一个纯质子导体. 在湿润空气气氛中, 材料的氧离子迁移数为0.688～0.170, 质子迁移数为0.218～0.017, 是一个氧离子、质子和电子空穴的混合导体. 在氢-空气燃料电池条件下, 材料的离子(氧离子＋质子)迁移数为0.990～0.796, 是一个氧离子、质子和电子的混合导体. 与化学计量组成的BaCe0.5Zr0.4La0.1O3－α材料相比较, 在相同实验条件下非化学计量组成的Ba1.03Ce0.5Zr0.4La0.1O3－α材料具有较高的电导率和离子迁移数.}     

基于第一性原理的无铅无机钙钛矿Cs3Bi2X9(X=Cl、Br、I)光电性能表面效应研究

用基于第一性原理的密度泛函理论方法,对Cs₃Bi₂X₉（X=Cl、Br、I）的光电特性进行理论计算,并系统阐述这3种晶体的表面效应对光电性能的影响。结果表明,3种材料的光学特性由铋原子和卤素原子最外层p轨道上的价电子主导。在可见光区中,材料的吸收峰会随卤素原子序数的增加呈现红移,其中一维结构的Cs₃Bi₂Cl₉表面结构在光吸收能力上尤为特别且敏感;二维结构的Cs₃Bi₂Br₉光吸收能力会受厚度影响;零维结构的Cs₃Bi₂I₉非常稳定,且几乎不受表面特性和晶体厚度的影响。     

基于第一性原理的无铅无机钙钛矿Cs3Bi2X9(X=Cl、Br、I)光电性能表面效应研究

用基于第一性原理的密度泛函理论方法,对Cs₃Bi₂X₉(X=Cl、Br、I)的光电特性进行理论计算,并系统阐述这3种晶体的表面效应对光电性能的影响。结果表明,3种材料的光学特性由铋原子和卤素原子最外层p轨道上的价电子主导。在可见光区中,材料的吸收峰会随卤素原子序数的增加呈现红移,其中一维结构的Cs₃Bi₂Cl₉表面结构在光吸收能力上尤为特别且敏感;二维结构的Cs₃Bi₂Br₉光吸收能力会受厚度影响;零维结构的Cs₃Bi₂I₉非常稳定,且几乎不受表面特性和晶体厚度的影响。     

Ba0.95Ce0.8Ho0.2O3-α的离子导电性

用高温固相反应法制备了Ba_0.95Ce_0.8Ho_0.2O_3-α，X–射线衍射表明，该材料为单相钙钛矿型斜方晶结构。以该材料为固体电解质，多孔性铂为电极，用气体浓差电池方法和交流阻抗谱方法分别测定了材料在600 ~ 1000℃温度范围，潮湿氢气、干燥和潮湿的空气中的离子迁移数和电导率，研究了该材料的离子导电性，并与BaCe_0.8Ho_0.2O_3-α作了比较。结果表明，在600 ~ 700 ℃、潮湿氢气中，Ba_0.95Ce_0.8Ho_0.2O_3-α是纯的质子导体，质子迁移数为1；在800 ~ 1000 ℃，是质子和电子的混合导体，质子迁移数为0.97 ~ 0.93。而BaCe_0.8Ho_0.2O_3-α在潮湿氢气中几乎是纯的质子导体，在600 ~ 900 ℃，质子迁移数为1；在1000 ℃，质子迁移数为为0.99。在600 ~ 1000℃温度范围内、干燥的空气中，它们都是氧离子和电子空穴的混合导体，氧离子迁移数分别为0.24 ~ 0.33和0.17 ~ 0.30；在潮湿的空气中，它们都是质子、氧离子和电子空穴的混合导体，质子迁移数分别为0.11 ~ 0.00 和0.09 ~ 0.01，氧离子迁移数分别为0.41 ~ 0.33和0.27 ~ 0.30。在潮湿的氢气和空气中，在600 ~ 800 ℃温度范围内，Ba_0.95Ce_0.8Ho_0.2O_3-α的质子电导率高于BaCe_0.8Ho_0.2O_3-α，但在800 ~ 1000 ℃温度范围内，Ba_0.95Ce_0.8Ho_0.2O_3-α的质子电导率则低于BaCe_0.8Ho_0.2O_3-α。在600 ~ 1000 ℃温度范围内、潮湿和干燥的空气中，氧离子电导率总是高于BaCe_0.8Ho_0.2O_3-α。     

层状锰酸锂衍生物的阳离子价态与锂电池的电化学性能研究

采用溶胶-凝胶法, 通过锂盐、镍盐、钴盐与锰盐生成锂镍钴锰氧化合物的前驱体, 随后采用高温固相法合成了Li(Mn_1/3Co_1/3Ni_1/3)O₂. 借助于X射线光电子能谱(XPS)、X射线衍射(XRD)、循环伏安(CV)及充放电测试等现代测试手段研究了材料的晶型结构、离子价态及电化学性能. 前驱体经950 ℃煅烧可获得晶体结构完整、晶胞参数为a＝0.2864 nm, c＝1.4235 nm的六方层状Li(Mn_1/3Co_1/3Ni_1/3)O₂化合物; XPS结果表明Li(Mn_1/3Co_1/3Ni_1/3)O₂化合物表面上的Mn, Ni和Co分别以Mn^4＋, Ni^2＋和Co^3＋存在; 材料的高温放电比容量比室温要高, 在55 ℃下, 在2.5～4.6 V电压范围内, 电流密度为28 mA/g时材料首次放电容量195 mAh/g, 循环10次后容量保持在170 mAh/g; 循环伏安曲线上3.7 V和4.4 V的氧化还原过程对应于Ni^2＋/4＋和Co^3＋/4＋氧化还原电对的反应.     

高温下硅酸锂吸收CO2的研究

以SiO₂和Li₂CO₃为反应原料，采用高温固相法于不同温度下合成了一系列可在高温500~750 ℃之间直接吸收CO₂的硅酸锂(Li₄SiO₄)材料。采用扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)分别观察和评价了合成材料的表面形貌与结构特征，用热重分析仪(TG)研究了硅酸锂材料吸收CO₂的性能。实验结果表明，在750 ℃下煅烧6 h即可合成出吸收CO₂性能良好的硅酸锂材料，在CO₂气氛下，于700 ℃保持约15 min即可达到吸收平衡，其吸收量约达43%(wt)左右。与文献报道相比，材料的合成条件有所改善，材料吸收CO₂的容量也有较大提高。     

(ZrO2)0.86(Sm2O3)0.14纳米粉体的水热法合成及其烧结体的电性能

以湿化学法制得Zr(OH)₄和Sm(OH)₃的共沉淀为前驱体, 在碱性介质中用水热法合成了(ZrO₂)_0.86(Sm₂O₃)_0.14及(ZrO₂)_0.88(Sm₂O₃)_0.12纳米粉体. 将纳米粉体在较低温度(1450 ℃)下烧结制得了致密的固体电解质陶瓷样品, 比通常高温固相反应法采用的烧结温度(＞1600 ℃)降低了150 ℃以上. XRD测定结果表明, (ZrO₂)_0.86(Sm₂O₃)_0.14纳米粉体及其烧结体均为立方相, 但(ZrO₂)_0.88(Sm₂O₃)_0.12纳米粉体为立方相, 它的烧结体为立方相和单斜相的混合相. 用交流阻抗谱法、氧浓差电池法及氧泵(氧的电化学透过)法研究了(ZrO₂)_0.86(Sm₂O₃)_0.14陶瓷样品在600～1000 ℃下的离子导电特性. 结果表明, 该陶瓷样品在600～1000 ℃下氧离子迁移数为1, 氧离子电导率的最大值为3.2×10^－2 S•cm^－1, 是一个优良的氧离子导体; 它的氧泵性能明显地优于YSZ.     

Li2ZrO3材料吸收CO2性能的进一步研究

用不同结构的ZrO₂合成了一系列在高温下吸收CO₂的Li₂ZrO₃材料，并详细的研究了反应物质的物理和化学性质对生成物吸收CO₂性能的影响。采用SEM、XRD以及TG分析法分别进行了材料结构及其吸收CO₂性能的表征，并使用XPS法测定了材料表面的元素组成。实验结果表明，使用不同结构的ZrO₂合成的Li₂ZrO₃，其吸收CO₂的性能明显的不同。用ZrO₂(t)(四方)合成的Li₂ZrO₃吸收CO₂的速度快，在500 ℃下，20% CO₂（80%空气）的气氛中保持3h，其吸收量可达25（±0.6）%（wt），而以ZrO₂(m)(单斜)为原料制备的Li₂ZrO₃在上述吸收条件下重量仅增加9（±0.6）%（wt）。此外，实验结果还表明化学元素的掺杂对用ZrO₂(m)合成的Li₂ZrO₃的CO₂吸收速度及吸收容量影响较大。     

掺杂和取代对红色荧光材料SrAl12O19:Mn4+发光性能的影响

SrAl₁₂O₁₉:Mn⁴⁺是一种用于高显色性白光发光二极管的候选红色荧光材料。本论文研究了Mg²⁺、Zn²⁺和Ge⁴⁺离子的掺杂效应以及Ge³⁺、Ca²⁺和Ba²⁺离子的取代效应SrAl₁₂O₁₉:Mn⁴⁺荧光材料性能的影响。样品通过高温固相反应制备,焙烧温度在1 250~ 1 500℃之间。利用X射线衍射技术表征了材料的相纯度,用荧光激发光谱和发射光谱表征了材料的荧光性能。研究结果指出,与未进行Mg²⁺或Zn²⁺掺杂的样品相比,Mg²⁺或Zn²⁺离子对Al³⁺格位的掺杂可以使材料的发光强度提高~60%,其原因被认为是掺杂促进了激活剂Mn⁴⁺离子进入晶格,其过程可以表示为:MO+MnO₂=M_Al''+Mn_Al^·+3O_O^×(M=Mg,Zn),电子顺磁共振谱支持这一结果。Ge⁴⁺离子的掺杂使材料的发光性能明显下降。Ge³⁺离子可以取代Al³⁺离子形成全范围的固溶体,其中少量Ge³⁺离子的掺杂可以使材料的荧光发射强度提高~13%,而掺杂量进一步提高使材料的荧光性能下降。Ca²⁺和Ba²⁺对Sr²⁺的取代仅形成有限范围的固溶体。Ca²⁺的取代使材料的发光性能提高;而 Ba²⁺的取代使材料的发光强度下降。     

葡萄糖B-Z体系中酸度变化诱导的复杂振荡反应

本文首次报导了葡萄糖-KBrO₃-丙酮-MnSO₄-H₂SO₄体系的化学振荡反应,在这一体系中改变酸度可产生一系列复杂的振荡现象,当[H₂SO₄]₀>0.36mol·l^-1或[H₂SO₄]₀<0.074mol·l^-1时,体系分别出现二种不同类型的振荡波形OA和OB,OA振荡存在一诱导期,OB振荡无锈导期;OA的振幅较小,但振荡频率比OB快得多;OB的振荡周期逐渐缩短,但OA.却相反变化.当0.074mol·l^-1<[H₂SO₄]₀<0.36mol·l^-1时,体系同时出现上述二种类型的振荡波形,中间存在一过渡区域,即产生连续振荡波形.文章讨论了诱导期及过渡时间与[H₂SO₄]₀的关系,对酸度的影响机理作了说明.     

Convenient synthesis of bis(indolyl)alkanes and bis(pyrrolyl)alkanes by Cu(OTf)2-catalyzed addition of indole and pyrrole to acetylenic sulfone

Sulfonyl-containing bis(indolyl)alkanes and bis(pyrrolyl)alkanes were synthesized conveniently by Cu(OTf)₂-catalyzed double Michael addition of indole and pyrrole to acetylenic sulfone.     

Thermal Decomposition of Bi(III), Cd(II), Pb(II) and Cu(II) Thiocyanates

Thermal decomposition of Bi(SCN)₃, Cd(SCN)₂, Pb(SCN)₂ and Cu(SCN)₂ has been studied. The thermal analysis curves and the diffraction patterns of the solid intermediate and final products of the pyrolysis are presented. The gaseous products of the decomposition (SO₂ and CO₂) were detected and quantitatively determined. Thermal, X-ray and chemical analyses have been used to establish the nature of the reactions occurring at each stage in the decomposition.This revised version was published online in November 2005 with corrections to the Cover Date.     

Effect of Bi0.75Y0.25O1.5 electrolyte additive in collector layer to properties of bilayer composite cathodes of solid oxide fuel cells based on La(Sr)MnO3 and La(Sr)Fe(Co)O3 compounds

The sintering features, electroconductivity, and electrochemical characteristics of bilayer electrodes with functional composite layers based on La(Sr)MnO₃ (LSM) and La(Sr)Fe(Co)O₃ with LSM collector layer and Bi(Y)O_1.5 (YDB) electrolyte additive in contact with Ce (Sm)O₂(SDC), La(Sr)Ga(Mg)O₃, and Zr(Sc)O₂ electrolytes were studied. YDB additive to the electrode collector layer was shown to produce a positive effect to the properties of the studied electrode systems. The maximum electrochemical activity and electroconductivity was observed for the electrodes with 5 wt % of YDB electrolyte additive in the collector layer. Thus, electroconductivity of electrodes is almost doubled and 100 mV cathode overvoltage current density is increased by 30% at the temperatures of 800 to 900°C and up to 10-fold at 650 to 700°C. The collector layer sintering temperature of bilayer electrodes can be reduced from 1150 to 1000°C without loss of electrochemical activity. The service life tests (about 1200 h) of composite electrodes with LSM2-SDC functional layer and 90% LSM2 + 10% YDB collector layer in contact with SDC electrolyte showed the time dependences of polarization resistance tending to saturation and described with damped exponent. Original Russian Text ? N.M. Bogdanovich, D.I. Bronin, G.K. Vdovin, I.Yu. Yaroslavtsev, B.L. Kuzin, 2009, published in Elektrokhimiya, 2009, Vol. 45, No. 4, pp. 486–494.     

Selective synthesis of mono- and distannylpyridines from chloropyridinols via an SRN1 mechanism

A selective two-step synthesis of either mono- or distannylated pyridines from commercially available pyridinols, involving its conversion to the corresponding diethyl pyridyl phosphates (pyDEP) followed by the reaction with Me₃SnNa in liquid ammonia, is described.The results obtained clearly indicate that the reactions proceed through an unimolecular radical nucleophilic substitution mechanism (S_RN1) with intermediacy of a monosubstitution product.     

Metathesis polymerisation of phenylacetylene catalysed by (arene)Mo(CO)3 activated by electron acceptor chloranil

Phenylacetylene (PA) was polymerised by employing (arene)Mo(CO)₃/chloranil mixture as the catalyst. Preliminary kinetic studies of the polymerisation showed the presence of an induction period before commencement of polymerisation, attributable to the activation of the (arene)Mo(CO)₃ by chloranil through charge-transfer. It was shown that better control over polymer molecular weight and polydispersity was achieved with prior mixing of the metal carbonyl complex with the acceptor and by delaying the addition of the monomer. Polymerisation by metathesis route was ascertained by copolymerisation, sequential addition of monomers and also by end-capping reactions.     

Tris(pentafluorophenyl)borane [B(C6F5)3]-catalyzed Friedel-Crafts reactions of activated arenes and heteroarenes with α-amidosulfones: the synthesis of unsymmetrical triarylmethanes

Tris(pentafluorophenyl)borane [B(C₆F₅)₃] has found to be an efficient catalyst for Friedel-Crafts reactions between activated arenes or heteroarenes and α-amidosulfones. The products undergo further Friedel-Crafts reactions with activated heteroarenes leading to the synthesis of unsymmetrical triarylmethanes. The present synthetic method displayed significant advantages such as low catalyst loading, mild reaction conditions, highly regioselective, high yield, and broad applicability to various substrates.     

Synthesis of Mono-Dispersed Mg(OH)2 Nanoflakelets

Mono-dispersed Mg(OH)₂ nanoflakelets have been prepared with the assistant of 4-(p-nitrophenylazo)resorcinol. The samples were characterized using XRD, TEM, and ED. Electron diffraction analysis showed that single crystalline nanoflakelets were obtained in hydrothermal process, and porous Mg(OH)₂ nanosheets were prepared at lower temperature. Nitrogen adsorption isotherms show that the surface area of Mg(OH)₂ nanosheets is 129 m²/g. Possible growth mechanism of the nanoflakelets is discussed.     

State(R)-state(TS)-state(P) theoretical study of H + H<Subscript>2</Subscript> system

The calculation of H + H₂ system by symplectic quasiclassical trajectory (SQCT) shows that there are two types of collision trajectories A and B, i.e., type A trajectory passes the saddle point of transition state (TS), whereas type B trajectory does not pass the saddle point of transition state. Not all the reactants of type A trajectory are reactive, while not all of type B trajectory are nonreactive. The partition and reactivity of these two types of trajectories are affected by reactant state(R), furthermore, the types of trajectories affect the state and angle distributions of products. Not only the rudiment framework for theoretical study on state(R)-state(TS)-state(P) is established, but also the further understanding of transition state theory (TST) of Eyring is investigated in this paper.     

三(三甲基硅烷)类添加剂助力5 V镍锰酸锂电池实用化

基于LiNi_0.5Mn_1.5O₄的5 V电池尚未实现实际应用,解决这一问题的关键在于电解液调控和电极界面优化。我们系统性研究了三（三甲基硅烷）硼酸酯（TMSB）和三（三甲基硅烷）亚磷酸酯（TMSPi）作为常规碳酸乙烯酯（EC）-LiPF₆基电解液添加剂在LiNi_0.5Mn_1.5O₄电池体系中的应用。结合理论计算、物理化学表征以及电化学手段分析了三（三甲基硅烷）类添加剂在高压电解液中的作用机制。研究发现,TMSB和TMSPi均可以通过优化电极/电解液界面来提高LiNi_0.5Mn_1.5O₄循环稳定性和库仑效率。TMSB中缺电子B可与阴离子相互作用,稳定PF₆^-,抑制LiNi_0.5Mn_1.5O₄正极阻抗的持续增加。TMSPi具有更高的最高占据分子轨道（HOMO）能级,可在更低电位下钝化高压正极,提高LiNi_0.5Mn_1.5O₄放电电压平台和放电容量。此外,TMSPi还可通过亲核反应参与石墨界面组分优化,改善负极循环性能。石墨LiNi_0.5Mn_1.5O₄软包电池在含1% TMSPi电解液中1C循环100次后的容量保持率为88.9%,优于基础电解液（60.5%）和含1% TMSB的电解液（77.4%）。