ZrO2和Al2O3在金红石型TiO2表面的包覆研究

以(NaPO3)6为分散剂,用化学沉积法对金红石型TiO2进行了锆、铝氧化物包膜。研究了包覆过程中,TiO2的分散、ZrO2和Al2O3用量、反应pH值以及时间对二氧化钛的亨特白度(Wh)和光泽度(L)的影响,并采用扫描电镜(SEM)、透射电镜(TEM)、X光电子能谱(XPS)和沉降性试验对包覆前后的二氧化钛进行了表征,得到包锆、包铝氧化物的优化工艺条件。研究了二氧化钛表面包锆、铝氧化物的包覆机理和表面结构。经过其表面包膜处理,二氧化钛的颜料性能得到明显改善。     

WC/TiO2纳米复合材料的制备及其电催化性能

以TiCl4为原料, 采用溶胶水解法合成了金红石型纳米TiO2颗粒, 并以其为载体制备了WC/TiO2纳米复合材料. 采用X射线衍射(XRD)、扫描电子显微镜(SEM)和X射线能谱(EDS)等手段分析了WC/TiO2纳米复合材料的晶相组成和表面形貌. 结果显示样品是由WC, TiO2和W组成, 纳米WC颗粒均匀地包覆在TiO2的表面, 并与TiO2构成了WC/TiO2纳米复合材料. 采用循环伏安法和计时电流法研究了WC/TiO2纳米复合材料对硝基苯的电催化性能. 结果表明, WC/TiO2纳米复合材料对硝基苯的电催化活性和电化学稳定性均优于介孔结构碳化钨(meso-WC)和纳米WC颗粒(part-WC).     

高容量材料Si@CPZS在锂离子电池中的储锂性能研究

本文通过简单的溶胶-凝胶法以聚环三磷腈-4,4'-磺酰基二苯酚聚合物（PZS）为碳源通过在硅纳米颗粒表面包覆碳层,成功构筑了核壳结构的Si@C复合材料. 通过对不同厚度碳层包覆的Si@C_PZS的储锂性能进行研究,发现当硅表面PZS衍生碳厚度为10 nm时具有最佳的储锂性能,且经过长达290圈的循环后容量仍然保持在940 mAh·g ^-1,并且利用X射线衍射图谱、热重、比表面孔径测定仪及透射电镜等分析手段对样品进行了结构和组分分析. 本文进一步将Si@C_PZS复合材料作为石墨的添加剂,结果表明30%的Si@C_PZS复合材料可将石墨负极的容量提升至700 mAh·g ^-1.     

Al2O3/TiH2包覆粉体的制备及其释氢性能的研究

TiH2颗粒可以作为多孔铝的发泡剂[1,2]. Al2O3包覆TiH2颗粒与未包覆的TiH2颗粒相比, 可以起到控制(延迟)其发泡的作用, 提高泡沫铝材料的孔隙均匀性. 然而, 目前采用的包覆方法是将细小Al2O3粉通过机械研磨包覆在TiH2表面[3].本文尝试采用化学法制备Al2O3/TiH2包覆颗粒, 并研究其包覆的效果. 用化学法制备Al2O3/TiH2包覆颗粒, 并用其作为多孔铝制备中的发泡剂, 此项研究在国内外尚未见报道.     

液相沉积法制备TiO2颗粒表面包覆SiO2纳米膜

研究了用液相沉积法在TiO2颗粒表面包覆SiO2纳米膜的过程.通过透射电镜(TEM)和酸溶实验分析,证实本实验在TiO2颗粒表面包覆了一层连续、致密的SiO2纳米膜.ζ-电位分析表明,颗粒表面只需少量包覆就可以显著改变颗粒表面的电动力学行为.采用 X射线荧光光谱分析仪（XRF）测定SiO2包覆量随包覆过程的变化.通过X射线光电子能谱（XPS）分析,获得Ti 2p、Si 2p及 O 1s电子结合能及其相对强度随包覆过程的变化规律,揭示硅酸分子在TiO2颗粒表面的包覆过程.分析表明,初期形成的活性硅酸分子与TiO2颗粒表面的羟基反应形成Ti－O－Si键,后期形成的硅酸分子与已键合在表面的硅酸发生缩合反应,形成连续致密的硅膜,膜层在陈化过程中继续缓慢生长.     

不同方法制备的CeO2-ZrO2体系结构研究

采用不同方法制备了几种CeO2-ZrO2二元氧化物体系,并用XRD、BET、XPS等技术研究了各个体系中氧化铈与氧化锆的存在状态.结果表明以773K焙烧过的氧化锆为载体,浸渍Ce(NO3)3溶液制得的CeO2/ZrO2体系中,氧化铈单层分散于氧化锆的表面,分散阈值约为0.03gCeO2/gZrO2.以水合氧化锆为载体,浸渍Ce(NO3)3溶液制得CeO2-ZrO2固溶体,但用此法制备的固溶体样品与用共沉淀法制备的样品不同.共沉淀法得到的是均一固溶体,浸渍法得到的是富锆固溶体和富铈固溶体的混合物;而且浸渍法制备的样品表面Ce/Zr原子比高,热稳定性好.     

碳包覆硅/石墨复合材料的制备及其电化学性能

本文以工业硅粉(600目)为原料,通过高能球磨和热解包碳方法制备了碳包覆纳米硅,在此基础上采用简单的机械球磨方法制备了碳包覆/石墨复合材料,并系统研究了碳包覆量及硅/石墨比例对碳包覆硅/石墨复合材料电化学性能的影响.与商业纳米硅粉/石墨复合材料相比,工业硅粉/石墨复合材料的循环性能及倍率性能均得到改善.通过高能球磨和热处理法得到的碳包覆材料为无定形碳和晶态硅材料的复合,所获碳包覆硅材料一次颗粒的粒径在100～200 nm左右.碳包覆量对材料的电化学性能有着重要影响,Si/C-2-1复合材料表现出高的可逆比容量、良好的倍率性能和循环稳定性,在0.1C倍率下,可逆比容量高达492.6 mA h·g~(-1),循环100周后容量保持率达85.8%,1C电流密度下放电比容量达369.7 mAh·g~(-1),为0.1C的73.9%.提高碳包覆硅/石墨复合材料中硅含量的比例可以提升其比容量,当硅含量达到20%时,Si/C-2-3复合材料在0.1C倍率下可逆比容量达到600.4 mAh·g~(-1),但材料循环性能有所下降,说明石墨在稳定硅/碳复合材料循环性能方面发挥着非常重要的作用.     

CeO2/Al2O3珠光材料的制备研究

以单晶片状氧化铝为基材,硝酸铈为铈源,NaOH为沉淀剂,采用液相沉积包覆法制备了氧化铈包覆片状氧化铝珠光材料。系统讨论了制备过程中溶液pH值、反应温度、铈盐种类以及铈盐滴加速率等条件对包覆效果的影响,使用X-射线衍射、金相显微镜和扫描电镜对包覆产物和煅烧产物进行了表征分析。实验结果表明最优反应条件为体系pH值为7.5,反应温度为75℃,加料速度为0.4～0.8 mL/min,煅烧温度为760℃时,反应生成的氢氧化铈能以纳米级颗粒形式均匀细密地包覆在片状氧化铝表面,煅烧后制得的CeO_2/Al_2O_3珠光材料产物的CeO_2包覆率可达25%,且具有良好的光学效果。     

纳米Sn-Co/石墨复合材料的制备、结构和电化学性能

以化学沉积法制备Sn-Co合金纳米粒子/石墨复合材料,XRD和Ram an光谱表征物相结构,SEM观察表面形貌.结果显示,500℃高温热处理的Sn-Co/石墨复合材料,其颗粒密集均匀地分散于石墨载体上.Sn-Co合金纳米粒子颗粒直径100 nm左右.Sn-Co/石墨电极具有较高的比容量和循环寿命,这可能是该合金纳米粒子与棒状石墨间的亲合能有效地阻止Sn的脱落,Sn-Co的颗粒间隙缓冲锂嵌脱过程的结构张力,防止合金的膨胀与粉化.     

聚苯乙烯包覆Y_2O_3:Eu~(3 )颗粒及表征

采用柠檬酸表面修饰 Y2 O3:Eu3 颗粒 ,苯乙烯乳液聚合的方法 ,制备出核 -壳型的 Y2 O3:Eu3 /聚苯乙烯颗粒 .在 FTIR谱图上 ,羰基伸缩振动峰向低波数位移 ;在 XPS谱图上 ,Y3d5 / 2 的电子结合能向高能方向移动 ,表明柠檬酸和颗粒表面发生键合作用 .说明此过程符合吸附层媒介作用机理 :柠檬酸使颗粒表面变成两亲性 ,从而使苯乙烯可吸附在颗粒表面形成包覆无机核的乳液结构 .EDS谱图表明聚苯乙烯均匀地包覆在颗粒表面     

Sc2MgGa2 and Y2MgGa2

Scandium magnesium gallide, Sc₂MgGa₂, and yttrium magnesium gallide, Y₂MgGa₂, were synthesized from the corresponding elements by heating under an argon atmosphere in an induction furnace. These intermetallic compounds crystallize in the tetragonal Mo₂FeB₂‐type structure. All three crystallographically unique atoms occupy special positions and the site symmetries of (Sc/Y, Ga) and Mg are m2m and 4/m, respectively. The coordinations around Sc/Y, Mg and Ga are pentagonal (Sc/Y), tetragonal (Mg) and triangular (Ga) prisms, with four (Mg) or three (Ga) additional capping atoms leading to the coordination numbers [10], [8+4] and [6+3], respectively. The crystal structure of Sc₂MgGa₂ was determined from single‐crystal diffraction intensities and the isostructural Y₂MgGa₂ was identified from powder diffraction data.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

The alkali hypophosphites KH2PO2, RbH2PO2 and CsH2PO2

The structures of the hypophosphites KH₂PO₂ (potassium hypophosphite), RbH₂PO₂ (rubidium hypophosphite) and CsH₂PO₂ (caesium hypophosphite) have been determined by single‐crystal X‐ray diffraction. The structures consist of layers of alkali cations and hypophosphite anions, with the latter bridging four cations within the same layer. The Rb and Cs hypophosphites are isomorphous.     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Formal [(2+2)+2] and [(2+2)+(2+2)] nonconjugated dienediyne cascade cycloadditions

[reaction: see text] Fluoranthene 2 and heptacycle 3 are easily accessible from the reaction of diyne 1 and norbornadiene (NBD) in the presence of the rhodium catalyst. The unusual [(2+2)+(2+2)] adduct 3 was confirmed by the X-ray crystal structure analysis.     

Crystal Structures of [Bu2Sn(O2PPh2)2], [Ph2Sn(O2PPh2)2], and [PhClSn(O2PPh2)OMe]2. Raman Spectra of [Ph2Sn(O2PPh2)2] and [PhClSn(O2PPh2)OMe]2

[(n‐Bu)₂Sn(O₂PPh₂)₂] ( 1 ), and [Ph₂Sn(O₂PPh₂)₂] ( 2 ) have been synthesized by the reactions of R₂SnCl₂ (R=n‐Bu, Ph) with HO₂PPh₂ in Methanol. From the reaction of Ph₂SnCl₂ with diphenylphosphinic acid a third product [PhClSn(O₂PPh₂)OMe]₂ ( 3 ) could be isolated. X‐ray diffraction studies show 1 to crystallize in the monoclinic space group P2₁/c with a = 1303.7(1) pm, b = 2286.9(2) pm, c = 1063.1(1) pm, β = 94.383(6)°, and Z = 4. 2 crystallizes triclinic in the space group , the cell parameters being a = 1293.2(2) pm, b = 1478.5(4) pm, c = 1507.2(3) pm, α = 98.86(3)°, β = 109.63(2)°, γ = 114.88(2)°, and Z = 2. Both compounds form arrays of eight‐membered rings (SnOPO)₂ linked at the tin atoms to form chains of infinite length. The dimer 3 consists of a like ring, in which the tin atoms are bridged by methoxo groups. It crystallizes triclinic in space group with a = 946.4(1) pm, b = 963.7(1) pm, c = 1174.2(1) pm, α = 82.495(6)°, β = 66.451(6)°, γ = 74.922(6)°, and Z = 1 for the dimer. The Raman spectra of 2 and 3 are given and discussed.     

Die Photoionenspektren von SCl2, S2Cl2 und S2Br2

Photoionization Mass Spectra of SCl₂, S₂Cl₂, and S₂Br₂ Photoionization mass spectra of SCl₂, S₂Cl₂, and S₂Br₂ have been measured. Heats of formation, bond energies, and ionization potentials of fragments have been calculated from appearance potentials.