Synthesis and crystal structure of a Pr5Ni19 superlattice alloy and its hydrogen absorption-desorption property

The intermetallic compound Pr(5)Ni(19), which is not shown in the Pr-Ni binary phase diagram, was synthesized, and the crystal structure was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Two superlattice reflections with the Sm(5)Co(19)-type structure (002 and 004) and the Pr(5)Co(19)-type structure (003 and 006) were observed in the 2θ region between 2° and 15° in the XRD pattern using Cu Kα radiation. Rietveld refinement provided the goodness-of-fit parameter S = 6.7 for the Pr(5)Co(19)-type (3R) structure model and S = 1.7 for the Sm(5)Co(19)-type (2H) structure model, indicating that the synthesized compound has a Sm(5)Co(19) structure. The refined lattice parameters were a = 0.50010(9) nm and c = 3.2420(4) nm. The high-resolution TEM image also clearly revealed that the crystal structure of Pr(5)Ni(19) is of the Sm(5)Co(19) type, which agrees with the results from Rietveld refinement of the XRD data. The P-C isotherm of Pr(5)Ni(19) in the first absorption was clearly different from that in the first desorption. A single plateau in absorption and three plateaus in desorption were observed. The maximum hydrogen storage capacity of the first cycle reached 1.1 H/M, and that of the second cycle was 0.8 H/M. The 0.3 H/M of hydrogen remained in the metal lattice after the first desorption process.     

钆对La-Mg-Ni系A_2B_7型储氢合金微观结构和电化学性能的影响

用高频感应熔炼方法制备了稀土系A2B7型La0.83-xGdxMg0.17N i3.05Co0.3A l0.15(x=0~0.5)储氢合金,在Ar气氛中和1173 K下对铸态合金进行退火处理,通过X射线衍射(XRD)、电子探针显微分析方法(EPMA)和电化学测试等分析方法系统研究了稀土Gd部分替代La元素对合金微观组织和电化学性能的影响规律。研究结果表明,合金退火组织主要由Ce2N i7型、Gd2Co7型、Pr5Co19型、PuN i3型和CaCu5型相组成,稀土Gd元素能有效减少和抑制退火组织中CaCu5型相的形成,随Gd含量x增加,合金相组成中A2B7型(Ce2N i7和Gd2Co7型)相丰度呈先增加后减小的规律,当x=0.2时其相丰度最大(91.0%)。合金的PCT吸氢平台压随Gd含量的增加而升高,x=0.5时吸氢平台压力接近0.1 MPa,x=0.2时合金的吸氢量达到最大值1.34%。电化学测试分析表明,随Gd含量x的增加,合金电极最大放电容量和容量保持率均呈先增加后减小的规律,适量的Gd元素可明显改善合金的综合电化学性能。当x=0.2时,合金电极放电容量达到最大值392.9 mAh.g-1,经100...     

退火处理对新型无镁Y0.7La0.3Ni3.25Al0.1Mn0.15储氢合金结构和电化学性能的影响

通过电弧熔炼制备了无镁La-Y-Ni系A₂B₇型Y_0.7La_0.3Ni_3.25Al_0.1Mn_0.15合金, 并在高纯0.2 MPa Ar气氛下分别对合金进行850~1050 ℃真空24 h退火热处理. 通过X射线衍射(XRD)、 中子衍射(ND)、 扫描电子显微镜/能量分散谱(SEM/EDS)和电化学测试方法研究了退火温度对合金结构和性能的影响. 结构分析表明, 铸态合金由CaCu₅, Ce₅Co₁₉, Gd₂Co₇, Ce₂Ni₇多相构成, 随着退火温度升高, CaCu₅, Ce₅Co₁₉, Gd₂Co₇相逐步减少直至消失, Ce₂Ni₇主相相丰度逐步增加. 900~950 ℃退火时, 合金为单相Ce₂Ni₇结构. 退火温度继续升高, 合金中出现少量PuNi₃相. 合金电极的最大放电容量随着退火温度的升高先增加后降低. 从铸态的307.6 mA·h/g增加到900 ℃退火时的最大值393.1 mA·h/g, 后又降到1050 ℃退火时的366.4 mA·h/g. 合金电极的电化学循环稳定性随退火温度的升高而升高, 循环100次后电化学容量保持率(S₁₀₀)从铸态的66%上升到1050 ℃退火后的88.5%, 900~950 ℃退火时, 合金电极具有较好的综合电化学性能.     

Mg/Mg1.8La0.2Ni纳米复合材料的吸放氢性能研究

应用高能球磨法制备Mg-x%Mg1.8La0.2Ni (x=10、20和30) 纳米复合储氢材料. X射线衍射(XRD)、透射电镜(TEM)和选区电子衍射(SAED)测试表明,该复合材料具有纳米晶和非晶态混合结构的性质,吸氢温度降低,较好的吸放氢动力学性能,在423K,2.5MPa氢压的条件下,50s内即可达到最大吸氢量.     

镁含量对RE-Mg-Ni系A2B7型储氢合金结构与性能的影响

采用感应熔炼方法制备了La0.8-xGd0.2MgxNi3.1Co0.3Al0.1(x=0, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4)储氢合金, 并在氩气气氛和1173 K下进行退火处理. 合金相结构分析结果表明, 镁含量(x)较低时合金以Ce2Ni7型为主相结构, A2B7型相丰度(Ce2Ni7+Gd2Co7)达到98.8%; 镁含量较高时合金相由A2B7型、 CaCu5型和PuNi3型物相构成, 随着镁含量的增加, PuNi3型和CaCu5型相组成逐渐增多, 其晶胞参数随Mg含量的增加而减小, 同时合金的吸氢平台也随之升高. 电化学测试结果表明, 随着合金中Mg含量增加, 合金电极的最大放电容量和循环稳定性均呈先增大后减小的规律, 其中x=0.15时合金电极具有最高的电化学放电容量(393 mA·h/g)和最佳的循环寿命(S100=92.82%). 合金电极的高倍率放电性能(HRD)随Mg含量的增加先减小再增大然后又减小, 适量的Mg元素改善了合金电极的动力学性能.     

基于3，4-吡啶二羧酸配体的钆(Ⅲ)配合物的合成、晶体结构及热性质

The hydrothermal reaction of pyridine-3,4-dicarboxylic acid (pydcH₂), 4,4′-bipyridine and GdCl₃·6H₂O yield a novel gadolinium coordination polymer {[Gd₂(pydc)₂(μ₃-OH)₂(H₂O)₂]·H₂O}_n(1). The compound was chara-cterized by elemental analysis, thermal analysis, IR spectra and single-crystal X-ray structure analysis. The crystal of the Gd(Ⅲ) complex belongs to triclinic system, space group P1 with: a=0.796 25(16) nm, b=0.944 46(19) nm, c=1.262 1(3) nm, α=76.50(3)°, β=84.95(3)°, γ=83.04(3)°, Z=2, V=0.914 4(3) nm³, D_c=2.669 g·cm^-1, μ=7.269 mm^-1, F(000)=692, and R₁=0.033 3, wR₂=0.062 3. The crystal structure revealed that compound 1 has a 2D layer structure incorporating 1D Gd-O-Gd double chain, and hydrogen bonding interactions result in the former of 3D supramolecular network structure. CCDC: 669079.     

基于5-甲基-3-吡唑甲酸为配体的钴(Ⅱ)、镍(Ⅱ)配合物的合成、晶体结构和电化学性质

利用5-甲基-3-吡唑甲酸、咪唑和相应醋酸盐在乙醇和水混合溶剂中反应,得到了配合物[M(MPA)2(Im)2].2H2O(1:M=Co;2:M=Ni)(HMPA=5-甲基-3-吡唑甲酸,Im=咪唑)。用元素分析、红外光谱、X-单晶衍射结构分析、热重分析、循环伏安等对其进行了表征。配合物1和2的晶体结构参数如下:配合物1和2的晶体都属于单斜晶系,空间群为P21/n。配合物1的晶胞参数为a=0.847 02(16)nm,b=1.461 5(3)nm,c=0.899 67(17)nm,β=101.759(6)°,V=1.090 3(4)nm3,Z=2;配合物2的晶胞参数为a=0.853 59(6)nm,b=1.451 77(9)nm,c=0.889 83(6)nm,β=102.382 0(10)°,V=1.077 04(12)nm3,Z=2。金属离子与来自2个5-甲基-3-吡唑甲酸配体中的2个氮原子及2个氧原子,2个咪唑分子中的2个氮原子配位,形成八面体配位构型。配合物中的独立结构单元[M(MPA)2(Im)2].2H2O通过2种分子间氢键(N-H…O和C-H…O)形成三维超分子。循环伏安性质测试表明配合物1和2的电解过程均为准可逆过程。     

氢化燃烧法合成La1.5Ni0.5Mg17的工艺优化

采用正交实验设计方法安排实验，运用L9(3^4)优化氢化燃烧法合成La1.5Ni0.5Mg17的工艺，考察了施压制饼时间、合成保温时间、合成起始氢气压力、保温温度4个因素对储氢材料的储放氢容量和速率的影响，通过直观分析和方差分析得出优化的工艺为：保温温度903K，制饼施压时间40min，合成起始氢气压力为1MPa，合成保温时间1800min。此条件下合成储氢材料La1.5M0.5Mg17在573K的储放氢容量分别为：5．40和5．15％H(质量分数)；储放氢速率分别为：0．734和0.681％H／min。用XRD分析了材料吸氢和脱氢后的物相结构发现：用Ni适量取代La2Mg17中的La没有导致结构变化，存在的LaNi5，LaH3和La改善了材料的吸放氢速率。     

超分子化合物[Ni(H2O)6]1.5·[Ni(ptc)(Hptc)]·(H2O)4的水热合成及晶体结构

以2,4,6-吡啶三甲酸(H3ptc)和六水合高氯酸镍为原料用水热方法合成了三维超分子配合物[Ni(H2O)6]1.5.[Ni(ptc)(Hptc)].(H2O)4,并经X射线衍射分析确定了其单晶结构.该晶体属三斜晶系,P墿空间群,晶胞参数为:a=1.03058(16)nm,b=1.11852(17)nm,c=1.4689(2)nm,α=74.725(2)°,β=77.777(2)°,γ=64.734(2)°,V=1.4675(4)nm3,Mr=798.20,Z=2,ρ=1.806g/cm3,F(000)=822,μ=1.701mm-1,R1=0.0373,wR2=0.0993.结果表明,在组成该超分子体系的基本结构单元[Ni(ptc)(Hptc)]3-和[Ni(H2O)6]2+中,Ni(Ⅱ)离子均处于变形八面体配位环境中.配合物单元之间通过氢键相互连接,形成了无限延伸的三维超分子网状结构.     

球磨La2Mg17+x％Ni(x=50,100,150,200)复合贮氢合金的电化学性能研究

研究了球磨制备的La2 Mg17+x％Ni(x =50,100,150,200)复合贮氢合金的电化学性能.XRD分析表明:随着Ni含量的增加,复合合金的晶体结构逐渐转变为非晶结构.电化学测试显示:球磨制备的La2Mg17+x％Ni复合贮氢合金在首次循环后即可达最大放电比容量,合金具有较好的活化性能;复合合金的放电比容量也随Ni粉加入量的增加而增大.在经过60h球磨后制得的非晶态的La2 Mg17+ 200％ Ni复合贮氢合金,其303 K下放电比容量为353.1 mAh·g-1.电化学放电比容量的提高应归因于非晶结构的形成以及Ni粉对表面状态的改变.     

Two-dimensional metallic chain compounds Y5M2Te2 (M = Fe, Co, Ni) that are related to Gd3MnI3. The hydride derivative Y5Ni2Te2D0.4

Y(5)M(2)Te(2) (M = Fe, Co, Ni) have been prepared by high-temperature solid-state techniques and shown to be isostructural and orthorhombic Cmcm (No. 63), Z = 4. The structure was established by single crystal X-ray methods at 23 degrees C for M = Fe, with a = 3.9594(3) A, b = 15.057(1) A, and c = 15.216(1) A. The new structure contains zigzag chains of the late transition metal sheathed by a column of yttrium atoms that are in turn condensed through trans vertices on the latter to yield 2D bimetallic layers separated by single layers of tellurium atoms. Reaction of hydrogen with Y(5)Ni(2)Te(2) causes a rumpling of the Y-Ni layers as determined by both single X-ray crystal means at 23 degrees C and neutron powder diffraction at -259 degrees C for Y(5)Ni(2)Te(2)D(0.41(1)), Pnma (No. 62), Z = 4. Lattice constants from the former study are a = 14.3678(7) A, b = 4.0173(2) A, and c = 15.8787(7) A. The hydrogen is accommodated in tetrahedral yttrium cavities generated by bending the formerly flat sheets at the trans Y vertices. A higher hydride version also exists. Band structure calculations confirm the 2D metal-bonded character of the compounds and also help illustrate the bonding/matrix changes that accompany the bonding of hydrogen. The ternary structures for both Y(5)M(2)Te(2) and Sc(5)Ni(2)Te(2) can be derived from that of Gd(3)MnI(3), the group illustrating three different kinds of metal chain condensation.     

TiO2改性的镁基中温吸附剂及其CO2吸附性能的研究

采用沉淀法合成一系列TiO₂改性的镁基吸附剂,利用XRD、SEM和氮气吸附等方法对吸附剂进行表征,通过变温吸附-脱附动态循环实验考察其CO₂吸附性能。随着TiO₂含量的增加,样品的结晶度逐渐下降,同时由于焙烧后生成钛酸镁,样品比表面积逐渐减小。当TiO₂添加量为2%(质量分数),此时吸附剂呈直径为4.0~5.0μm的球形,局部为纳米片状结构,该吸附剂自第二次循环开始吸附能力无明显变化;经过50次变温吸附脱附循环实验后,动态吸附容量可达6.64%(质量分数),这是由于TiO₂改性后生成的钛酸镁为该吸附剂提供了刚性骨架,促进了活性组分的分散,并提高了吸附剂的稳定性。     

复合半导体负载金属材料光催化性能研究

CO₂和烃类光催化直接合成烃类氧化物在合成化学、碳资源利用和环境保护等方面均有重大意义。用溶胶-凝胶和浸渍-还原相结合的方法制得M/V₂O₅-TiO₂(M=Pd、Cu、Ni和Ag)光催化剂。利用XRD、TPR、IR、TPD、UV-Vis DRS和光反应器等技术研究了负载金属复合半导体的物相结构、吸附性能、光吸收性能和光催化反应性能。结果表明：金属负载在复合半导体上延迟了TiO₂由锐钛矿向金红石相的转化,增强了V与载体TiO₂的相互作用,使TiO₂光吸收限发生蓝移,对可见光部分的吸收明显增加,拓宽了催化剂的光响应范围;材料吸光性能强弱顺序Pd/V₂O₅-TiO₂ >Cu/V₂O₅-TiO₂ >Ag/V₂O₅-TiO₂>Ni/V₂O₅-TiO₂;材料的吸附性能及反应物的吸附态是反应发生的关键,CO₂在Ag/V₂O₅-TiO₂表面无法形成卧式吸附态,没有目的产物甲基丙烯酸(MAA)生成,光量子效率低;光吸收性能较好的Pd/V₂O₅-TiO₂对CO₂吸附能力过强,卧式吸附态脱附温度高,光催化效率不高;Cu/V₂O₅-TiO₂对CO₂吸附能力适中,CO₂与C₃H₆脱附温度较接近,实现了“光-表面-热”的协同作用,光量子效率最高,达15.1%。     

Mg1.8La0.2Ni-xNi nanocomposites for electrochemical hydrogen storage

Mg1.8La0.2Ni hydrogen storage alloy was ball-milled with Ni powder, leading to the formation of a nanocrystalline and amorphous microstructure with particle sizes less than 50 nm in diameter. Each sample was examined by transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). This structure was beneficial for the reduction of electrochemical impedance, as well as significant improvement of its discharge capacity, cycle life, and rate capability for electrochemical hydrogen storage in an alkaline solution. When the molar ratio (x) of Ni over Mg1.8La0.2Ni was equal to 2, the dehydriding capacity reached 2.55 wt % from electrochemical pressure-temperature isotherms (P-C-T). It was in good agreement with its initial discharge capacity, 716 mA*h/[g of (Mg1.8La0.2Ni)], observed from the electrochemical charge and discharge process. After 50 cycles, its discharge capacity still reached 381 mA*h/[g of (Mg1.8La0.2Ni)]. Further results showed that this composite had a promising high rate capability. At the current density of 1200 mA/g its discharge capacity reached 48% of its initial capacity.     

苯四甲酸桥连的镍配合物[Ni(btec)(H2O)4][Ni(imi)2(H2O)4]·2H2O的合成及结构

At room temperature, a coordination polymer [Ni(btec)(H2O)4][Ni(imi)2(H2O)4]·2H2O was synthesized by reaction of NiCl2·6H2O, 1,2,4,5-benzenetetracarboxylic dianhydridc and imidazole in a water/THF solution. The structure was determined by X-ray diffraction crystal structure analysis. It crystallizes in triclinic P1 space group with the crystal cell parameters of a=0.67542 (2) nm, b=1.000 14 (1) nm, c=1.09088 (3) nm, α=74.140(2)°, β= 74.388(1)°, y=73.239(2)°, and V=0.664 09(3) nm3, Z=1. The crystal structure shows that Ni1 atom is coordinated by four water and two imidazole molecules, while Ni2 is coordinated by four water molecules and two carboxyl oxygen atoms. The 1,2,4,5-benzenetetracarboxylate ions bridge Ni2 coordination centers to form one-dimensional chain structure. Moreover, the chains are further linked together by hydrogen bonds to form a two-dimensional network. CCDC: 295873.     

萘磺酸型离子配合物的合成及其分子识别性能

常温反应条件下制备了4个基于乙二胺和1,5-萘二磺酸的配位化合物[M(en)(H_2O)_4]·1,5-nds·(H_2O)_2(M=Ni(1),Co(2),Cd(3),Cu(4),nds=1,5-萘二磺酸;en=乙二胺),并通过红外光谱、元素分析、X射线单晶衍射、X射线粉末衍射和热重分析等技术手段确定了其晶体结构。结构分析表明,该系列配合物属于同构体系,单斜晶系,C2/c空间群。以配合物1为例,其晶胞参数为a=1.69026(19)nm,b=1.01373(11)nm,c=1.3448(3)nm,α=90°,β=120.2650°,γ=90°,V=1.9901(5)nm~3,Z=4,Dc=1.713 g/cm~3,F(000)=1072,R_1=0.0326,wR_2=0.0867。该系列配合物的中心金属为六配位模式,与来自乙二胺的2个N原子和4个H_2O中的氧原子配位。游离水与磺酸氧和配位水之间存在着丰富的氢键作用,构筑成三维的网络结构。测定了以Cd为中心金属配合物3的荧光光谱,发现其在对于甲醇的小分子识别性能方面具有应用前景。     

具有双螺旋链的新型二维无机-有机骨架晶体材料Ni(PDC)(H2O)2的合成与结构

本文报道由H2PDC合成的新型维层状无机-有机骨架晶体Ni(PDC)(H2O)2(H2PDC=吡啶-2,5-二羧酸), 该化合物的一层是由右手螺旋Ni—O—C链与左手螺旋Ni-pdc链组成, 而邻近的一层则是由左手螺旋Ni—O—C链与右手螺旋Ni-pdc链组成, 层与层之间通过氢键作用形成了三维超分子结构. 用ICP、TG、IR和X射线单晶衍射分析等手段对其结构进行表征.     

新型吡啶基羧酸席夫碱配体镍配合物的合成和晶体结构

通过新合成的吡啶基羧酸席夫碱配体（5-(吡啶基-3-亚甲基氨基)间苯二甲酸H2L）,和镍盐反应制备了一个新的镍配合物{[Ni(HL)₂(H₂O)₂]·2H₂O}_n(1),利用元素分析及X-射线单晶衍射对其进行了表征。结构分析结果表明标题化合物属于三斜晶系,P1 空间群,晶胞参数为a=0.764 79(11) nm,b=0.870 49(13) nm,c=1.081 13(16) nm,α=85.583(2)°,β=82.614(2)°,γ=81.565(2)°,V=0.704 82(18) nm³,Z=1,D_c=1.586 g·cm^-3,μ=0.763 mm^-1,F(000)=350。在配合物的结构中,Ni(Ⅱ)的配位构型为畸变的八面体。配合物中每个配体通过羧酸氧和吡啶氮原子和金属配位形成一维链状结构,并通过体系中丰富的氢键作用链接成为三维框架并加以稳定。     

二茂铁基正庚基β-二酮的合成及晶体结构

在氢化钠存在下,用乙酰基二茂铁与正辛酸乙酯进行缩合反应,合成了标题化合物FeCOCH2COC7H15(Fc=C5H5FeC5H4).X射线衍射测定其晶体学数据为:C20H26FeO2,空间群P21/n,a=0.5790(1)nm,b=4.1634(4)nm,c=0.7635(1)nm,β=101.39(1)°,Z=4.最终的偏离因子R=0.050.结构分析表明,该化合物分子以烯醇式形式存在,通过分子内氢键,形成六元环,环中O…H氢键距离为0.146nm.β-二羰基中与正庚基相连接的羰基易于烯醇化。     

以二羧基苯氧乙酸为配体的一维钆(Ⅲ)配位聚合物的合成及晶体结构

利用Williamson合成法合成了3,5-二甲氧酰基苯氧乙酸甲酯(ML),并以之作为配位前驱物与氯化钆在水热条件下发生原位水解-配合反应,得到了3,5-二羧基苯氧乙酸(H3L)与Gd髥形成的一维配位聚合物[H3L2Gd(H2O)4]n,用X-射线单晶衍射法对其进行了结构表征。测定结果表明,该配合物结晶于单斜晶系,C2/c空间群,晶胞参数:a=1.534 4(3)nm,b=2.074 9(3)nm,c=0.716 08(16)nm,β=103.49°,V=2.216 90(225)nm3,Z=4,Dc=2.117 01 g.cm-3。Gd(III)金属中心处于扭曲的双帽三棱柱配位几何构型的中心,与来自4个配体的4个羧基氧原子结合,4个配位水分子则占据了配位环境中剩余的4个顶点。Gd髥金属中心由二齿的配体以Gd-O键连接成Ln2L4型结构单元,并进一步通过共用Gd髥金属中心的方式连接形成一维长链结构。