First principle study of LiXS_2(X=Ga,In) as cathode materials for Li ion batteries

From first principle calculations, we demonstrate that LiXS_2(X = Ga, In) compounds have potential applications as cathode materials for Li ion batteries. It is shown that Li can be extracted from the LiXS_2 lattice with relatively small volume change and the XS_4 tetrahedron structure framework remains stable upon delithiation. The theoretical capacity and average intercalation potential of the LiGaS_2(LiInS_2) cathode are 190.4(144._2) m Ah/g and 3.50 V(3.53 V). The electronic structures of the LiXS_2 are insulating with band gaps of _2.88 eV and 1.99 eV for X = Ga and In, respectively.However, Li vacancies, which are formed through delithiation, change the electronic structure substantially from insulating to metallic structure, indicating that the electrical conductivities of the LiXS_2 compounds should be good during cycling.Li ion migration energy barriers are also calculated, and the results show that Li ion diffusions in the LiXS_2 compounds can be as good as those in the currently widely used electrode materials.     

固体颗粒的结构演化与机械力化学效应

干法、室温振动研磨制备铝超微颗粒, 分别将研磨2 h, 4 h和8 h的铝粉, 在常温下超声水解得到白色Al(OH)₃胶体, 水解产品经干燥、研磨、焙烧后制备出多孔、片状γ -Al₂O₃纳米颗粒, 粒度分布在30---50 nm之间. 借助于X射线衍射(XRD)分析方法和透射电子显微镜(TEM), 研究固体颗粒在细化过程中的能量转换, 分析颗粒的微结构演化与机械力化学反应的关系, 确定理想的研磨时间. 研究结果表明: 固体颗粒在机械力的作用下产生大量的应变和位错缺陷, 使材料处于亚稳、高能活性状态, 易于诱发机械力化学反应, 在一定条件下晶体的表面能、应变能和层错能相互转化; 研磨2 h的铝颗粒内部, 晶格畸变和位错概率最大, 材料显示出极高的化学反应活性, 在超声波激发下, 储存在材料内部的能量被充分释放, 在较短的时间内, 水解生成Al(OH)₃纳米颗粒.     

铈对果蝇、家蚕寿命及蚕茧重量的影响

研究了不同浓度氯化亚铈对果蝇寿命,家蚕寿命及其茧重的影响,实验分两部分;（１）用不同浓度的氯化亚铈加入培养基中饲养黑腹果蝇,结果显示１３３ｍｇ／Ｌ浓度时雌果蝇,２６６ｍｇ／Ｌ浓度时雄果蝇的寿命显著延长（Ｐ〈０．０５）;（２）用不同浓度的氯化亚铈溶液浸泡桑叶,风干后分别喂养四眠期的家蚕,浓度分别为１６,３２ｍｇ／Ｌ时家蚕重量显著增加（Ｐ〈０．０５）,在４,８,１６ｍｇ／Ｌ２时家蚕寿命显著延长（Ｐ〈０     

SYNTHESES OF POLYMER-BOUND RHODIUM COMPLEXES AND THEIR APPLICATION AS CATALYSTS FOR THE HYDROFORMYLATION OF DIISOBUTYLENE (Ⅰ)

Copolymer of styrene-divinylbenzene in bead form (with DVB 8%, average pore radius 3.0×10~2, specific surface area 25m~2/g, particle size 0.2—0.4mm) was made by the suspension polymerization. After chloromethylation, the beads were then reacted with lithium diphenyl phosphine and various amines separately. Two types of polymeric ligands, i.e. polyvinylbenzyl diphenyl phosphine and eight kinds of polyvinylbenzyl amines were thus obtained. In order to prepare the polymer-bound rhodium complexes, the ligands were then reacted with [Rh(CO)_2CI]_2. The initial composition and structure of the polymeric complexes were verified by IR spectra. The complexes synthesized above were used to catalyze the hydroformylation of diisobutylene under conditions of 110℃, 100(120) kg/cm~2 and H_2/CO=1:1. The effects of the donor atoms (N, P) on the activity of the two types of catalysts and the N-substituted groups on the activity 'of polymeric amine-rhodium complexes were examined.     

纳米多晶NiTi形状记忆合金超弹性的晶粒取向依赖性相场研究

论文基于Ginzburg-Landau理论,建立了一个反映纳米多晶NiTi形状记忆合金取向依赖性的二维多晶相场模型,研究了晶粒取向对其超弹性性能的影响.结果 表明,纳米多晶NiTi形状记忆合金的超弹性行为依赖于晶粒取向分布,即:多晶模型中在所研究的参数变化范围内,晶粒取向分布范围越广、晶粒间取向差越大(无明显织构),超...     

掺P25水热法制备纳晶多孔TiO2薄膜电极

以水热法为基础,向其溶胶中掺入适量的P25(二氧化钛粉体),来制备纳晶TiO₂胶体,以纳晶TiO₂为电子传输体组装染料敏化太阳能电池.通过XRD、SEM、UV-vis和电池的光电性能测试,来分析掺入P25对染料敏化太阳能电池性能的影响.结果表明,加入适量P25([P25]/[Ti]=0.2)后,染料敏化太阳能电池性能达到最佳值,在100 mW/cm²光照条件下,光电转换效率达到5.4%.     

二维GaAs 基光子晶体微腔的制作与光谱特性分析

研究了以InAs量子点为有源区的二维GaAs基光子晶体微腔的设计与制作,测试并分析了室温下微腔的光谱特性.观察到了波长约为1137 nm,谱线半高宽度约为1 nm的尖锐低阶谐振模式发光峰.我们比较了不同刻蚀条件下光子晶体微腔的发光谱线,结果表明空气孔洞截面的垂直度是影响光子晶体微腔发光特性的重要因素之一.通过调节干法刻蚀工艺,改变空气孔半径与晶格常数的比率,可以在较大范围内调节谐振模式发光峰位置,达到谐振模式与量子点发光峰调谐的目的.     

BEPCⅡ高频系统的建造

北京正负电子对撞机二期(BEPCⅡ)的高频系统已于2006年11月投入运行,它包括了3个子系统:超导腔、发射机和低电平控制系统.与以前的高频系统相比,工作频率由200MHz变为499.8MHz,超导腔取代了常温腔.在过去一年的运行中,高频系统表现良好,达到了设计指标.     

半群PCS_n的极大子半群

设C_n是X_n上的循环群,SP_n=P_n\S_n称为X_n上的部分奇异变换半群.通过对变换半群PCS_n=C_n∪SP_n的元素的分析,获得了变换半群PCS_n的极大子半群的完全分类.     

Rapid Thermal Annealing Effects on Structural and Optical Properties of Self-Assembled InAs／GaAs Quantum Dots Capped by InAIAs／InGaAs Layers

Effects of rapid thermal annealing on the optical and structural properties of self-assembled InAs/GaAs quantum dots capped by the InAlAs/InGaAs combination layers are studied by photoluminescence and transmission electron microscopy. The photoluminescence measurement shows that the photoluminescence peak of the sample after 850℃ rapid thermal annealing is blue shifted with 370meV and the excitation peak intensity increases by a factor of about 2.7 after the rapid thermal annealing, which indicates that the InAs quantum dots have experienced an abnormal transformation during the annealing. The transmission electron microscopy shows that the quantum dots disappear and a new InAlGaAs single quantum well structure forms after the rapid thermal annealing treatment. The transformation mechanism is discussed. These abnormal optical properties are attributed to the structural transformation of these quantum dots into a single quantum well.