醋酸锰体系中钛材电沉积MnO2阳极的析氧催化性能

目前,对钛材在醋酸锰[Mn(CH3COO)2]电解液中电沉积MnO2层作析氧催化材料的研究还不充分.通过X射线衍射确定了MnO2沉积层的晶型,用扫描电镜观察了其表面形貌;以循环伏安、极化曲线和电化学阻抗等方法测试了钛材MnO2沉积层电极的电化学性能,探讨了MnO2沉积层电极的结构、形貌与电催化性能的关系.结果表明:醋酸锰电解液中MnO2电沉积速度较快,用其制备的阳极析氧电催化性能较好.     

超级电容器MnO2/CRF复合电极材料的制备及性能的研究

以间苯二酚(R)和甲醛(F)为原料,碳酸钠(C)为催化剂,制备碳气凝胶(CRF),并以KMnO4和Mn(CH3COO)2·4H2O为原料,采用了化学沉淀法制备MnO2/CRF复合材料.用N2吸附、X射线衍射(XRD)和扫描电镜(SEM)对所制备的MnO2、CRF和MnO2/CRF复合材料进行了表征,结果表明碳气凝胶具有珍珠串式的无序多孔网络结构,所制备的MnO2为纳米级颗粒,复合材料为纳米级粉体.并对不同配比的MnO2/CRF复合材料的电化学性能进行了研究.循环伏安、恒流充放电实验表明了所制备的MnO2/CRF复合电极材料具有良好的可逆性和充放电性能.当MnO2含量为60%时,MnO2与碳气凝胶复合制成的新型电极材料具有226.3F/g的比电容,比碳气凝胶电极的比电容提高了1倍.此外,对复合电极的循环寿命进行了研究,表明复合电极具有良好的循环充放电性能.     

MnO2的机械化学法制备及其性能

采用机械化学法制备了MnO2粉体,研究了不同高锰酸钾与乙酸锰配比对产物结构与性能的影响.用X射线衍射、红外光谱、扫描电镜、BET等方法研究了产物的结构及形貌;用恒电流充放电方法考察了MnO2超级电容器在6 mol/L KOH电解液中的电容性能.结果表明,原料中乙酸锰含量增多,产物结晶度增大,颗粒粒径变小,但电极比电容却从504F/g减小到388 F/g;当高锰酸钾:乙酸锰摩尔配比为2:2和2:3时,所得产物超级电容器在200 mA/g电流,0～1 V范围,电极放电容量分别达到了504 F/g和516 F/g.放电过程中,MnO2超级电容器在不同电压范围表现出不同的电容特性:在1～0.67 V和0.4～0 V范围内主要为双电层电容,在0.67～0.4 V范围内主要是法拉第假电容.     

十二烷基苯磺酸钠对MnO_2电化学性能影响的研究

在表面活性剂十二烷基苯磺酸钠(SDBS)存在下,采用液相共沉淀法制备了二氧化锰(MnO2)电极材料,研究了SDBS对其结构、形貌和电化学性能的影响。利用傅利叶变换红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)对所制备MnO2结构和形貌进行了表征。在1mol/L Na2SO4溶液中,通过循环伏安法(CV)、恒电流充放电(CD)和交流阻抗法(EIS)测试了电极材料的电化学性能。结果表明,SDBS对MnO2的晶型无明显影响,但使其粒径尺寸减小,形貌发生变化。MnO2的比电容随SDBS浓度的增加先增大后减小,SDBS浓度为0.023mol/L时制得的MnO2比电容可达193F/g(电流密度为1A/g),而不加SDBS时制得的MnO2比电容为156F/g。     

Ti/SnO2+SbOx/MnO2(Ce)电极制备及性能表征

采用热分解法制备了不同浓度稀土元素铈掺杂钛基二氧化锰电极,通过SEM、极化曲线和EIS测试等方法分析了自制电极的形貌、催化性能和废水处理效果等.结果表明:适量铈元素的掺杂能改善二氧化锰电极的表面形貌,提高电极的析氯电催化活性,增强电极的耐蚀性和稳定性;使其在氯化钠电解质体系中处理亚甲基蓝印染废水的色度去除率达到96.9％,COD去除率达到91.8％.     

纳米二氧化锆对制备PbO2-CeO2-ZrO2复合阳极材料的影响

通过复合电沉积的方法制备新型三价铬镀铬用PbO2-CeO2-ZrO2惰性阳极材料,采用电化学方法测试分析电极材料的沉积机理、耐蚀性和催化活性;利用扫描电镜和能谱观察电极材料的微观形貌和元素含量。结果表明:镀层的沉积符合Johnson机理,PbO2的沉积过程非常稳定;ZrO2浓度为20g/L制备的复合惰性阳极材料耐蚀性好,催化活性高;ZrO2的加入对镀层的微观形貌影响不明显,随镀液中ZrO2浓度增大,镀层中CeO2的含量总体稳定,ZrO2的含量呈现先增大后减小的趋势。     

Ni-纳米TiO2复合电镀层的制备与性能研究

用电镀的方法制备出Ni-纳米TiO2复合电镀层,讨论了表面活性剂、阴极电流密度、搅拌速率等对复合镀层硬度的影响并分析了纳米TiO2的加入对复合镀层硬度、耐蚀性的影响情况.结果表明,与纯镍镀层相比,Ni-纳米TiO2复合电镀层的硬度可提高90～190 HV;添加阳离子表面活性剂分散纳米TiO2所得复合镀层硬度最高,说明阳离子表面活性剂有利于纳米TiO2-Ni复合电沉积.浸泡试验表明,在硝酸溶液中复合镀层的腐蚀速率高于纯镍镀层的腐蚀速率,但远低于未镀覆钢板的腐蚀速率;极化曲线表明,与纯镍镀层相比,复合镀层的自腐蚀电位没有显著提高.说明在复合镀层中添加纳米TiO2不能改善其耐蚀性.     

铝基二氧化锰电极的制备

采用电沉积法制备铝基MnO2电极,通过Tafel曲线、阳极极化曲线考察了镀液组成、施镀时间、施镀温度、电流密度对电极催化活性和耐蚀性的影响。考察了温度对镀层形貌的影响,最优条件下制备的MnO2电极分别在120℃、250℃、320℃和400℃条件下焙烧4h,结果表明,在120℃和250℃焙烧所得MnO2的结晶程度比不焙烧时增大了20%,而320℃和400℃焙烧所得MnO2的结晶程度比不焙烧时略有增加;物相和晶型都没有发生明显变化。因此得出制备铝基MnO2电极的最佳镀液组成和工艺条件为:MnSO4.H2O 150g/L,H2SO450g/L,温度80℃,电流密度3mA/cm2,施镀时间75min,120℃焙烧4h。所得电极催化活性较好,耐蚀性较强。经XRD表征主要晶型为γ-MnO2,SEM表征为球状堆积物。     

NaAlO2含量对ZAlSi12Cu2Mg1铝合金Na2SiO3微弧氧化陶瓷膜性能的影响

为了进一步探明添加剂种类及含量对ZAlSi12Cu2Mg1铝合金微弧氧化陶瓷膜性能的影响,在Na2SiO3电解液中,添加不同浓度的NaAlO2进行了微弧氧化,利用能谱仪(EDS)分析了陶瓷膜表面元素含量,用扫描电镜(SEM)观察其表面形貌,以X射线衍射仪(XRD)分析了膜的相组成,并测试了膜的厚度、硬度和极化曲线;研究了NaAlO2添加量对微弧氧化陶瓷膜特性的影响。结果表明,随着NaAlO2添加量的增加,陶瓷膜表面微孔尺寸变小,表面Al,O元素含量下降;起弧电压和最终氧化电压下降;陶瓷膜厚度增加,硬度和耐蚀性先提高后下降;陶瓷膜的相组成改变不明显。NaAlO2添加量为1 g/L时陶瓷膜的综合性能最好。     

发射状OMS2型MnO2的制备及其超级电容性能

在不同的反应时间下水热法控制制备发射状超级电容器用MnO2电极材料,采用X射线衍射光谱(XRD)、扫描电镜(SEM)表征其结构,采用循环伏安、恒流充放电和交流阻抗研究其电化学电容性能。结果表明,制备的MnO2为隐钾锰矿型,具有发射状结构,随着反应时间的延长,MnO2的晶型从不完善逐渐变得完善,发射状结构逐渐明显、增大,并且MnO2辐射出的每根单枝从较细的纳米刺逐渐生长为四方结构的纳米棒;在5mA/cm2的电流密度下,最高比电容达到了448F/g;随着反应时间的增加,MnO2电极的比容量先增长再降低。     

Comparison of the Electronic Structures of La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2

First-principles cluster calculations are reported of the local electronic structure of the three compounds: La₂CuO₄, Sr₂CuO₂Cl₂, and Sr₂CuO₂F₂. The copper and the planar oxygen 2p atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the atomic orbital lowered significantly in energy for chlorine and fluorine apical positions.     

Superconductivity of barium-doped Bi2Sr2CaCu2Oy

Sintered ceramic samples of Bi₂Sr_2–x Ba _x CaCu₂O_y with nominal barium fraction 0x0.3 have been prepared by the solid-state reaction method. WDS studies verified that barium enters the superconducting phase. For slowly cooled samples, the midpointT _c of the superconducting transition is significantly increased by barium doping, whereas for quenched samplesT _c is little affected. The increase ofT _c with increasing barium fraction is consistent with a decrease in the hole concentration in the superconducting layers.     

Quasiparticle dispersion of Sr2CuO2Cl2

Recent angle resolved photoemission (ARPES) measurements for the insulating cuprate Sr₂CuO₂Cl₂ have provided the first experimental data which can be directly compared to the (theoretically) well-studied problem of a single hole propagating in an antiferromagnet. Some discrepancies withthe familiar 2D t— J model were observed. Here we discuss a comparison between the ARPES results and the quasiparticle dispersion of both (i) the extended t— t— J Hamiltonian and (ii) the three-band Hubbard model.     

Reactivity of the H2O2/TiO2 system

The reactivity of the H₂O₂/TiO₂ system for samples treated at atmospheric pressure is studied by means of Auger Electron Spectroscopy. The most significant changes on the TiO₂ ‘final’ state are: (i) The I(O)/I(Ti) peak-to-peak ratio is diminished by 15%. (ii) The LMV transition suffers an energy shift of +2 eV, whereas the peak-to-peak width diminishes 1.5 eV. (iii) Its structure changes with respect to that of the TiO₂ ‘initial’ state although it is not identified with any one of the known stoichiometric oxides. (iv) When the samples that represent the ‘final’ state are heated up to 650 K, the AES spectrum matches quite well that of the TiO₂ ‘initial’ state.     

Ti/SnO2+Sb2O3+MnO2/PbO2阳极的性能研究

制备了一种非贵金属阳极－Ｔi/SnO2 Sb2O3 MnO2/PbO2,并用ＸＲＤ、ＳＥＭ进行了表征,计算出了电极的分形维数,测定了该电极在硫酸中的使用寿命和动力学参数,把该电极用于处理含酚废水和Ｐb电极进行对,结果表明,节电３３％,转化率达９５％,是一种优良的电化学催化剂。     

MgO-Al2O3-SiO2-TiO2-Y2O3玻璃的弹性模量

根据硬盘基板用材料的要求，制备了MgO-Al2O3-SiO2-TiO2-Y2O3高弹性模量玻璃（120GPa)，玻璃的弹性模量随组成的变化服从Makishima-Mackenzie理论，MgO,Al2O3,TiO2,Y2O3等具有较高单位体积离解能的氧化物有利于提高玻璃的弹性模量，但玻璃弹性模量的理论计算值低于测试值，这是因为Makishima-Mackenzie理论没有考虑玻璃内阳离子的具体配位，对MgO,Y2O3堆积密度因子的堆导存在误差，因此利用Makishima-Mackenzie理论发展高弹性模量玻璃时应对MgO,Y2O3等氧化物的计算进行修正。     

Subsolidus phase equilibria in the Al2O3-CeO2-PbO and Al2O3-CeO2-RuO2 systems

The subsolidus phase equilibria in air for the Al₂O₃-CeO₂-PbO and Al₂O₃-CeO₂-RuO₂ systems were studied with the aim of obtaining information on possible interactions between a CeO₂-based solid electrolyte in solid-oxide fuel cells (SOFCs) and other oxides. No ternary compound was found in either of the systems. The tie line in the Al₂O₃-PbO-CeO₂ system is between Al₂Pb₂O₅ and the CeO₂.     

Photoluminescence of lanthanide-doped CaSi2O2N2 phosphors and the energy-level diagram of lanthanide ions in CaSi2O2N2

Lanthanide-doped CaSi₂O₂N₂ phosphors were synthesized by solid-state reaction. Their photoluminescence (PL) properties were investigated and analyzed systematically. Energy transitions attributed to electron transfers from 4f to 4f (ff), from 4f to 5d (fd), from 5d to 4f (df) and charge transfer (CT) transition were obtained and classified. Finally, an energy-level diagram of lanthanide-ions in CaSi₂O₂N₂ was proposed. The diagram matches perfectly with the experimental results and explains the luminescence properties of lanthanide-doped CaSi₂O₂N₂ phosphors. The electron-vibrational interaction in 4f-5d optical transitions of CaSi₂O₂N₂:Eu²⁺ was also studied.     

Les phases SrLa2Al2O7 et SrGd2Al2O7

SrLa₂Al₂O₇ and SrGd₂Al₂O₇ belong to the structural type Sr₃Ti₂O₇. In SrGd₂Al₂O₇ strontium and gadolinium occupy respectively the 12 and 9 coordinated sites, whereas in SrLa₂Al₂O₇ the homologous cations are statistically distributed. The fluorescence spectra of both phases activated by Eu³⁺ ions show that the only possible position of Eu³⁺ is the 9 coordinated site.     

La2O3在MgO-Al2O3-SiO2-TiO2微晶玻璃中的作用

在MgO-Al2O3-SiO2-TiO2玻璃中添加不同数量的氧化镧，采用差热分析，X射线衍射及电子显微镜等技术研究了氧化镧对玻璃析晶过程与力学性能的影响。氧化镧的加入使玻璃中析出α－堇青石相的温度降低，同时避免了高膨胀方石英相的析出。随着氧化镧加入量的增加，玻璃整体析晶能力下降，微晶玻璃中晶相含量减少，晶粒尺寸增大，微晶玻璃的弹性模量与硬度减小，断裂韧性增加，体现出大尺寸长柱状金红石晶粒的增韧作用。