PbO~2纳米粉体的固相合成及其对MnO~2电极材料的改性作用

利用固相氧化反应制备了PbO~2纳米粉体样品，借助XRD，TEM以及循环伏安测试对其性质进行了表征。同时，对反应条件的选择进行了讨论。将所得样品用于改性MnO~2电极，恒流放电测试结果表明，样品掺杂量在1.25%～5.00%间对MnO~2有良好的改性效果，可使改性MnO~2的放电容量得到极大提高。循环伏安测试结果表明，铅的掺入改变了MnO~2的放电机理。在循环扫描过程中，掺杂物与MnO~2均不再以单纯氧化物的形式存在，而是形成了一系列Pb(X)(X=0,Ⅱ)Mn(Y)(Y=Ⅳ，Ⅲ，Ⅱ)复合物的共氧化与共还原，抑制了电化学惰性物质Mn~3O~4的生成和积累，从而有望改善MnO~2的可充性能。纳米PbO~2与常粒径PbO~2与常粒径PbO~2(标记为S)对MnO~2的改性机理类似。但前者对MnO~2的改性效果明显优于后者，当恒流放电至-1.0V时，其放电容量较S样改性MnO~2的放电容量平均高出约30%。     

Selection of Anodic Material Used in Electrolytic Process for Producing Hypophosphorous Acid

Black lead, Ti-Ru and Ti-PbO2 were used as anode and stainless steel was used as cathode The electrolytic process of producing hypophosphorous acid with four-compartment electrodialytic cell was studied. The comparison of some factors, such as anodic voltage, product concentration and current efficiency, of black lead, Ti-Ru, and Ti-PbO2 electrodes was conducted. As a result, theTi-PbO2 electrode is the optimal anode material used, it can be in electrolytic process for producing hypophosphorous acid.     

负载PbO催化剂对苯胺与碳酸二甲酯合成苯氨基甲酸甲酯的催化性能

 考察了几种负载PbO催化剂对苯胺(An)与碳酸二甲酯(DMC)反应合成苯氨基甲酸甲酯(MPC)的催化性能. 结果表明, PbO/SiO2对该反应表现出很高的催化活性. 当w(PbO)=3.6%, n(PbO)/n(An)=1%, n(DMC)/n(An)=5, θ=160 ℃和t=4 h时, MPC收率达到99.5%. PbO/SiO2容易从反应体系中分离,且可重复使用5次,催化活性基本保持不变,使用寿命较长.     

铅锑电极上PbO2生长过程的阻抗跟踪法研究

铅锑电极上ＰｂＯ_２生长过程的阻抗跟踪法研究韦国林，杨鸿兴，王家荣（上海大学嘉定校区化学系，上海，２０１８００）利用交流阻抗技术研究Ｐｂ／Ｈ２ＳＯ４体系中电化学过程，通常采用某一等效电路，并对所得的多频率阻抗频谱进行拟合处理，由此获得相关电化学信息。?..     

α-PbO纳米粉体的固相合成及其对MnO2电极材料的改性作用

利用Pb(Ⅱ）盐与NaOH在室温下进行固相反应制备的纳米级α－PbO粉体（桔红色）,借助X射线衍射、透射电镜测试对合成的纳米粉体试样拨乱反正了表征,初步探讨了反庆机理,将合成的试样用于改性MnO2电极,1次深度放电测试结果表明,样品的掺杂量在1.25％－5.00%之间对MnO2有良好的改性效果,中等负荷放电时,纳米PbO改性的MnO2电极的放电容量比常粒径PbO改性的MnO2电极的放电容量高出20％以上,比纯国际1^#电解锰样（γ-MnO2）的放电容量平均高出约50％,在重负荷放电时,改性MnO2电极的放电容量提高幅度更大。     

铅基复合钙钛矿型弛豫铁电单晶的生长基元与生长机理: II.成 分、结构起伏与 同型生长基元的分异和组装

铅基复合钙钛矿型弛豫铁电单晶体PMNT,PZNT的生长基元为多种[BO~6]配位八面体。这些同型生长基元受本身稳定性的制约而在熔体中存在的几率不同。相对于[MgO~6]^1^0^-,[ZnO~6]^1^0^-八面体基元来说,[NbO~6]^7^-,[TiO~6]^8^-是更为有利的八面体基元。在基元组装过程中,各种[BO~6]八面体基元在稳定性、尺寸大小与电价上的分异致使生长界面对基元有一定的选择性,从而造成了晶体生长时成分与结构的短程起伏,并为有序畴及其它化学缺陷团簇的形成提供了条件。当加入掺质PbTiO~3时,由于[TiO~6]^8^-与[NbO~6]^7^-两种基元在组装时的类聚性及[TiO~6]^8^-对晶体稳定性的贡献,晶体的微区成分与结构得以调制,焦发石相得以抑制,这构成了用Bridgman法能直接从熔体中生长出纯钙钛矿相PMNT单晶的基础。而[MgO~6]^1^0^-与[ZnO~6]^1^0^-八面体基元的差致使PMNT,PZNT两单晶的生长难度有别,这在选择合适的生长方法时需加以考虑。     

Physical Properties of Novel Lead-Bismuthate Glasses with Large Transmitting Windows

Novel lead-bismuthate glasses with low OH concentration have been obtained in the Bi2O3-PbO-SrO system. The role of the different components in the glass formation has been explored from the density, refractive index measurements, indicating that the physical properties are mainly agected by Bi2O3 and PbO contents. The densities and refractive indices of these glasses are in the ranges of 7.639-7.699 g/cm^3 and 2.47-2.94, respectively. A wide transmitting window from visible to infrared (IR) regions and good thermal stability for some compositions of these g/asses have been observed, which make them appealing candidates for different optical applications suc has upconverting phosphors, new laser materials, optical waveguides and crystal-free fibre drawing.     

Visible Upconversion Emission in Er3＋—Doped GeO2—PbO—PbF2 Glass

The upconversion fluorescence emission of Er3 -doped 60GeO2-2OPbO-2OPbF2 glass was experimentally investigated under the pump of 976-nm laser diode. The results reveal the existence of intense emission bands centred around 524, 545, and 657nm at room temperature. The green emission at 524 and 545nm is due to the 4S3/2 2 Hll/2→ 4I15/2 transition and the red emission of 657nm originates from the 4F9/2-→4I15/2 transition of Er3 . The quadratic dependence of the green and red emissions on excitation power indicates that a two-photonabsorption process occurs under the 976-nm excitation. The excited- state absorption from 4I ll/2 and the cross relaxation between two Er3 ions in the 4I ll/2 state contribute to the green emission. The red emission at 657nm is attributed to the excited-state absorption and cross relaxation processes in the 4I13/2 level as well as the 4S3/2 level nonradiative transition of Er3 .     

阳极氧化铅膜的光电流频谱曲线随膜增厚而位移的研究

铅在硫酸溶液中生长的阳极氧化铅膜的光电流频谱曲线随着膜增厚而红移。Dimitrov等认为长波对光电流的贡献随着膜的增厚而增大的程度要较短波的为大, 从而导致曲线的位移。我们的研究表明其主要原因为膜中的t-PbO和o-PbO的比例随膜增厚而发生的变化, 并非如上所述。本工作求出上述阳极膜中的t-PbO和o-PbO的禁带宽度分别为1.9和2.6eV。     

铅基复合钙钛矿型弛豫铁电单晶的生长基元与生长机理1: PMNT单晶的表面形貌 、负晶结构及生长基元的组装与拆分

铅基复合钙钛矿型弛豫铁电单晶体PMNT的生长基元为多种[BO~6]配位八面体,晶体生长过程可视为多种八面体基元与Pb^2^+的组装过程。这些生长基元向{111}面叠合时易采取法向生长机制,向{001}面叠合时易采取层状生长机制,由此决定了晶体生长速度的各向异性与晶体的形貌。Bridgman法生长的PMNT晶体在生长过程中由内向生长机制形成规则的负晶结构;在晶体生长过程中,在其自然表面上可形成正形与负形两种形貌;在高温退火过程中,由于PbO的分解,晶体表面上可形成类似"蚀象"的构型,这些可从[BO~6]八面体生长基元的组装或拆分方面获得解释。