锂电池阴极材料Li(CoxAl1-x)O2的溶胶-凝胶法合成及表征

采用溶胶-凝胶方法合成了锂二次电池阴极材料Li(CoxAl₁-x)O₂,并采用XRD方法分析了材料的相变过程、烧结时间对材料合成的影响及不同Al/Co比掺杂对材料相变的影响,并进行了结构表征.研究表明,材料结构随Al固溶度的增大及温度的升高呈现出a轴缩短,c轴伸长的趋势.材料晶相稳定温度在600～900℃之间,烧结时间在3h以上.     

LiNi1-xAlxO2(x=0～0.6)的制备和结构演变

通过研究LiNiO2和α-LiAlO2的制备条件,合成出LiNi1-xAlxO2(x=0～0.6)材料.XRD和XPS测试结果表明,各样品均具有α-NaFeO2型单相结构,并形成LiNi1-xAlxO2固溶体.随着Al固溶量x的增加,材料Ni(Al)—O结合能增加,晶胞的a轴缩短,c/a比增大,层状属性更加明显,结构稳定性增强.烧结实验结果表明,在低Al固溶量时,材料的合成需要在氧气气氛中进行,Al掺杂能够抑制结构中的Li缺位,降低材料形成温度及其在合成过程中对氧气的依赖程度.     

La1-xCaxCrO3体系复合氧化物的甘氨酸-硝酸盐法合成与表征

采用甘氨酸-硝酸盐法(GNP)合成了La1-xCaxCrO3 (x=0～0.3)体系复合氧化物粉料,对合成产物的粉体结构和性能进行了表征,研究了体系组成及合成方法对材料烧结性能和导电性能的影响.实验结果表明,在La1-xCaxCrO3体系中Ca2 离子的引入促进了材料的烧结,随着Ca2 离子含量的增加,材料的烧结致密度和导电性能明显提高.与常规固相法相比,GNP法合成的粉料颗粒细小均匀(100～200 nm),烧结活性高,其烧结体在1400 ℃以下即可达到较高的烧结致密度和良好的电性能.     

Ce_(1-x)Ca_xO_(2-x)的溶胶-凝胶法的合成及其性质

用溶胶 -凝胶法合成了 Ce1-x Cax O2 -x(x=0～ 0 .3 5 )系列固体电解质 ,系统地研究了其晶体结构随Ca O含量的变化关系 .XRD测试表明 ,该体系于 1 60℃即形成萤石结构纯相 .高温 XRD表明 ,从室温至80 0℃ ,Ce1-x Cax O2 -x(x=0～ 0 .3 5 )未出现结构相变 .此法合成温度远低于传统的高温固相合成法和水热合成法的温度 .合成物的颗粒小 ,粒度均匀 .在 1 3 0 0℃即可烧结成高致密度样品 .XPS测试表明 ,掺杂 Ca O后吸附氧浓度明显增大 ,氧空位增多 ,电导率和氧离子迁移数增大 ,改善了 Ce O2 基固体电解质的性能 .     

接枝共聚法制备聚乙二醇(PEG)/聚乙烯醇(PVA)高分子固-固相变材料性能研究

用接枝共聚法将具有相变特征的聚乙二醇(PEG)接枝到具有较高熔点的聚乙烯醇(PVA)主链上,得到了系列性能稳定的PEG/PVA高分子固-固相转变材料,用DSC,WAXD和POM对其相变行为及形态结构进行了研究.结果表明,该材料呈现出可逆的固-固相转变特性;其结晶峰值温度和相变焓比纯PEG低,接枝率对相变温度和归一化相变焓影响不大;接枝率只影响结晶与熔融行为,不影响结晶结构.     

碱土金属修饰Al_2O_3的表面热稳定性

采用浸渍法添加不同碱土金属元素对γAl2O3进行改性.通过BET、XRD等手段研究考察了在1373K空气中经不同时间处理γAl2O3的相变和烧结情况比较了各样品烧结后比表面积的差异.结果表明碱土金属的引入(尤其是Sr、Ca)有效地抑制了氧化铝比表面积的损失和α相变.并对Al2O3的烧结动力学进行了研究探讨研究表明铝酸盐的生成并不是稳定氧化铝的根本原因碱土金属的高温稳定作用主要是分散态的碱土金属氧化物抑制氧化铝焙烧过程中最初1h内的烧结和α相变引起的比表面积损失.     

La1-xCarCrO3体系复合氧化物的甘氨酸-硝酸盐法合成与表征

采用甘氨酸-硝酸盐法(GNP)合成了La1-xCarCrO3(x=0～0．3)体系复合氧化物粉料，对合成产物的粉体结构和性能进行了表征，研究了体系组成及合成方法对材料烧结性能和导电性能的影响。实验结果表明，在La1-xCarCrO3体系中Ca^2 离子的引入促进了材料的烧结，随着Ca^2 离子含量的增加，材料的烧结致密度和导电性能明显提高。与常规固相法相比，GNP法合成的粉料颗粒细小均匀(100～200nm)，烧结活性高，其烧结体在1400℃以下即可达到较高的烧结致密度和良好的电性能。     

Ce0.8Sm0.2O1.9的尿素燃烧法合成与性能

采用以尿素为燃料的燃烧合成法制备Ce0.8Sm0.2O1.9(SDC)氧离子导体材料, 对燃烧合成粉体的物相和显微形态进行了表征, 并研究了燃烧法合成SDC的烧结性能以及烧结体的导电性能. 研究结果表明, 采用尿素燃烧法合成SDC具有简便高效和合成粉体烧结活性高的优点. 经过燃烧过程后即可得到立方萤石结构的纯相SDC粉体, 合成粉体的分散性良好, 为50~150 nm的球形颗粒, 具有高的烧结活性, 在1250 ℃的烧结温度下, 陶瓷样品的相对密度可达到95.1%. 在600和800 ℃的测试温度下, 烧结温度为1250 ℃的陶瓷样品的电导率分别达到5.4×10-2和1.0×10-1 Ω-1·cm-1.     

MgO掺杂Ce_(0.9)Sm_(0.1)O_(2-δ)固体电解质的结构和电性能

采用溶胶-凝胶法合成SiO2含量为5.0×10-4(w)的Ce0.9Sm0.1O2-δ(SDC)粉体(SDCSi),并将0-3.0%(x)MgO分别加入到SDCSi陶瓷粉体中,用X射线衍射(XRD)和场发射扫描电子显微镜(FE-SEM)对材料进行表征,用交流阻抗谱(AC)测试材料的电性能.结果表明:MgO掺杂能使SDCSi的烧结温度降低100-200℃,提高陶瓷材料的致密度;清除或降低陶瓷材料晶界处SiO2杂质的有害影响,显著提高晶粒/晶界电导率和总电率;MgO掺杂到SDCSi具有烧结助剂和晶界杂质清除剂的双重作用.     

不同温度下聚铝碳硅烷的合成与表征

为了研究合成温度对聚铝碳硅烷(PACS)结构的影响, 采用具有Si—C骨架结构的低分子量液态聚碳硅烷(LPCS)与乙酰丙酮铝[Al(AcAc)3]为原料, 在300, 360和420 ℃下分别合成了固态PACS, 并对合成的PACS样品进行元素组成及结构表征. 表征结果显示, 合成温度明显影响样品的Al, O含量及Si—H键数量. 合成温度升高, Al含量与O含量增大, 但PACS中的Si—H键数量急剧减少, 在360 ℃下合成的样品具有理论Al含量, 而在300和420 ℃下合成的样品的Al含量分别小于和大于理论Al含量. 27Al MAS NMR结果显示, Al与O形成AlO4, AlO5和AlO6 三种配位形式. 反应过程中消耗Si—H键形成Si—O—Al交联结构是PACS数均分子量及多分散系数增加的主要原因.     

Unique {H(SiR(3))(2)}, (H(2)SiR(3)), H(HSiR(3)), and (H(2))SiR(3) ligand sets supported by the {Fe(Cp)(L)} platform (L=CO, PR(3))

This work deals with the type and incidence of nonclassical Si--H and H--H interactions in a family of silylhydride complexes [Fe(Cp)(OC)(SiMe(n)Cl(3-n))H(X)] (X=SiMe(n)Cl(3-n), H, Me, n=0-3) and [Fe(Cp)(Me(3)P)(SiMe(n)Cl(3-n))(2)H] (n=0-3). DFT calculations complemented by atom-in-molecule analysis and calculations of NMR hydrogen-silicon coupling constants revealed a surprising diversity of nonclassical Si--H and H--H interligand interactions. The compounds [Fe(Cp)(L)(SiMe(n)Cl(3-n))(2)H] (L=CO, PMe(3); n=0-3) exhibit an unusual distortion from the ideal piano-stool geometry in that the silyl ligands are strongly shifted toward the hydride and there is a strong trend towards flattening of the {FeSi(2)H} fragment. Such a distortion leads to short Si--H contacts (range 2.030-2.075 A) and large Mayer bond orders. A novel feature of these extended Si--H interactions is that they are rather insensitive towards the substitution at the silicon atom and the orientation of the silyl ligand relatively the Fe--H bond. NMR spectroscopy and bonding features of the related complexes [Fe(Cp)(OC)(SiMe(n)Cl(3-n))H(Me)] (n=0-3) allow for their rationalization as usual eta(2)-Si--H silane sigma-complexes. The series of "dihydride" complexes [Fe(Cp)(OC)(SiMe(n)Cl(3-n))H(2)] (n=0-3) is different from the previous two families in that the type of interligand interactions strongly depends on the substitution on silicon. They can be classified either as usual dihydrogen complexes, for example, [Fe(Cp)(OC)(SiMe(2)Cl)(eta(2)-H(2))], or as compounds with nonclassical H--Si interactions, for example, [Fe(Cp)(OC)(H)(2)(SiMe(3))] (16). These nonclassical interligand interactions are characterized by increased negative J(H,Si) (e.g. -27.5 Hz) and increased J(H,H) (e.g. 67.7 Hz).     

Syntheses and structures of the infinite chain compounds Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14)

The alkali metal/group 4 metal/polychalcogenides Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) have been synthesized by means of the reactive flux method at 823 or 873 K. Cs(4)Ti(3)Se(13) crystallizes in a new structure type in space group C(2)(2)-P2(1) with eight formula units in a monoclinic cell at T = 153 K of dimensions a = 10.2524(6) A, b = 32.468(2) A, c = 14.6747(8) A, beta = 100.008(1) degrees. Cs(4)Ti(3)Se(13) is composed of four independent one-dimensional [Ti(3)Se(13)(4-)] chains separated by Cs(+) cations. These chains adopt hexagonal closest packing along the [100] direction. The [Ti(3)Se(13)(4-)] chains are built from the face- and edge-sharing of pentagonal pyramids and pentagonal bipyramids. Formal oxidation states cannot be assigned in Cs(4)Ti(3)Se(13). The compounds Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) crystallize in the K(4)Ti(3)S(14) structure type with four formula units in space group C(2)(h)()(6)-C2/c of the monoclinic system at T = 153 K in cells of dimensions a = 21.085(1) A, b = 8.1169(5) A, c = 13.1992(8) A, beta = 112.835(1) degrees for Rb(4)Ti(3)S(14);a = 21.329(3) A, b = 8.415(1) A, c = 13.678(2) A, beta = 113.801(2) degrees for Cs(4)Ti(3)S(14); a = 21.643(2) A, b = 8.1848(8) A, c = 13.331(1) A, beta = 111.762(2) degrees for Rb(4)Hf(3)S(14); a = 22.605(7) A, b = 8.552(3) A, c = 13.880(4) A, beta = 110.919(9) degrees for Rb(4)Zr(3)Se(14); a = 22.826(5) A, b = 8.841(2) A, c = 14.278(3) A, beta = 111.456(4) degrees for Cs(4)Zr(3)Se(14); and a = 22.758(5) A, b = 8.844(2) A, c = 14.276(3) A, beta = 111.88(3) degrees for Cs(4)Hf(3)Se(14). These A(4)M(3)Q(14) compounds (A = alkali metal; M = group 4 metal; Q = chalcogen) contain hexagonally closest-packed [M(3)Q(14)(4-)] chains that run in the [101] direction and are separated by A(+) cations. Each [M(3)Q(14)(4-)] chain is built from a [M(3)Q(14)] unit that consists of two MQ(7) pentagonal bipyramids or one distorted MQ(8) bicapped octahedron bonded together by edge- or face-sharing. Each [M(3)Q(14)] unit contains six Q(2)(2-) dimers, with Q-Q distances in the normal single-bond range 2.0616(9)-2.095(2) A for S-S and 2.367(1)-2.391(2) A for Se-Se. The A(4)M(3)Q(14) compounds can be formulated as (A(+))(4)(M(4+))(3)(Q(2)(2-))(6)(Q(2-))(2).     

A crossed molecular beam study on the formation of hexenediynyl radicals (H(2)CCCCCCH; C(6)H(3) (X(2)A')) via reactions of tricarbon molecules, C(3)(X(1)Sigma(g)(+)), with allene (H(2)CCCH(2); X(1)A(1)) and methylacetylene (CH(3)CCH; X(1)A(1))

Crossed molecular beams experiments have been utilized to investigate the reaction dynamics between two closed shell species, i.e. the reactions of tricarbon molecules, C(3)(X(1)Sigma(g)(+)), with allene (H(2)CCCH(2); X(1)A(1)), and with methylacetylene (CH(3)CCH; X(1)A(1)). Our investigations indicated that both these reactions featured characteristic threshold energies of 40-50 kJ mol(-1). The reaction dynamics are indirect and suggested the reactions proceeded via an initial addition of the tricarbon molecule to the unsaturated hydrocarbon molecules forming initially cyclic reaction intermediates of the generic formula C(6)H(4). The cyclic intermediates isomerize to yield eventually the acyclic isomers CH(3)CCCCCH (methylacetylene reaction) and H(2)CCCCCCH(2) (allene reaction). Both structures decompose via atomic hydrogen elimination to form the 1-hexene-3,4-diynyl-2 radical (C(6)H(3); H(2)CCCCCCH). Future flame studies utilizing the Advanced Light Source should therefore investigate the existence of 1-hexene-3,4-diynyl-2 radicals in high temperature methylacetylene and allene flames. Since the corresponding C(3)H(3), C(4)H(3), and C(5)H(3) radicals have been identified via their ionization potentials in combustion flames, the existence of the C(6)H(3) isomer 1-hexene-3,4-diynyl-2 can be predicted as well.     

Organic acid solutions in the chromatography of inorganic ions VIII. Cation-exchange of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media

Summary The cation-exchange behaviour of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media at various concentrations and pH, was studied with Dowex 50 WX8 resin (200–400 mesh) in the ammonium form. Separation of Fe(III)/Cu(II), Fe(III)/Cu(II)/Zn(II), Fe(III)/Co(II)/Mn(II), Cu(II)/Ni(II)/Mn(II), Fe(III)/Cu(II)/Co(II)/Mn(II), Fe(III)/Cu(II)/Ni(II)/Cd(II), Yb(III)/Eu(III), Sc(III)/Y(III),Sc(III)/Yb(III)/Dy(III) and Nb(V)/Yb(III)/Ho(III) has been achieved, among others.This work was supported by C.N.R. of Italy.     

Hexaaquacobalt(II) bis(hypophosphite) and hexaaquacobalt(II)/nickel(II) bis(hypophosphite)

The title compounds, hexa­aqua­cobalt(II) bis­(hypophosphite), [Co(H₂O)₆](H₂­PO₂)₂, and hexa­aqua­cobalt(II)/nickel(II) bis(hypophosphite), [Co_0.5Ni_0.5(H₂O)₆](H₂PO₂)₂, are shown to adopt the same structure as hexa­aqua­magnesium(II) bis­(hypophosphite). The packing of the Co(Ni) and P atoms is the same as in the structure of CaF₂. The Co^II(Ni^II) atoms have a pseudo‐face‐centred cubic cell, with a = b～ 10.3 Å, and the P atoms occupy the tetrahedral cavities. The central metal cation has a slightly distorted octahedral coordination sphere. The geometry of the hypophosphite anion in the structure is very close to ideal, with point symmetry mm2. Each O atom of the hypophosphite anion is hydrogen bonded to three water mol­ecules from different cation complexes, and each H atom of the hypophosphite anion is surrounded by three water mol­ecules from further different cation complexes.     

Phosphine-boranes as bidentate ligands: formation of [8,8-eta(2)-(eta(2)-(BH(3)).dppm)-nido-8,7-RhSB(9)H(10)] and [9,9-eta(2)-(eta(2)-(BH(3)).dppm)-nido-9,7,8-RhC(2)B(8)H(11)] from [8,8-(eta(2)-dppm)-8-(eta(1)-dppm)-nido-8,7-RhSB(9)H(10)] and [9,9-(eta(2)-dppm)-9-(eta(1)-dppm)-nido-9,7,8-RhC(2)B(8)H(11)], respectively

The two clusters [8,8-(eta(2)-dppm)-8-(eta(1)-dppm)-nido-8,7-RhSB(9)H(10)] (1) and [9,9-(eta(2)-dppm)-9-(eta(1)-dppm)-nido-9,7,8-RhC(2)B(8)H(11)] (2) (dppm = PPh(2)CH(2)PPh(2)), both of which contain pendant PPh(2) groups, react with BH(3).thf to afford the species [8,8-eta(2)-(eta(2)-(BH(3)).dppm)-nido-8,7-RhSB(9)H(10)] (3) and [9,9-eta(2)-(eta(2)-(BH(3)).dppm))-nido-9,7,8-RhC(2)B(8)H(11)] (4), respectively. These two species are very similar in that they both contain the bidentate ligand [(BH(3)).dppm], which coordinates to the Rh center via a PPh(2) group and also via a eta(2)-BH(3) group. Thus, the B atom in the BH(3) group is four-coordinate, bonded to Rh by two bridging hydrogen atoms, to a terminal H atom, and to a PPh(2) group. At room temperature, the BH(3) group is fluxional; the two bridging H atoms and the terminal H atom are equivalent on the NMR time scale. The motion is arrested at low temperature with DeltaG++ = ca. 37 and 42 kJ mol(-1), respectively, for 3 and 4. Both species are characterized completely by NMR and mass spectral measurements as well as by elemental analysis and single-crystal structure determinations.