Thermodynamic properties of Cu-3(CO3)(2)(OH)(2) and the spin-1/2 distorted diamond Heisenberg chain

The thermodynamic properties of the spin-1/2 diamond quantum Heisenberg chain model have been investigated by means of the transfer matrix renormalization group (TMRG) method. Considering different crystal structures, by changing the interactions among different spins and the external magnetic fields, we first investigate the magnetic susceptibility, magnetization, and specific heat of the distorted diamond chain as a model of ferrimagnetic spin systems. The susceptibility and the specific heat show different features for different ferromagnetic (F) and antiferromagnetic (AF) interactions and different magnetic fields. A 1/3 magnetization plateau is observed at low temperature in a magnetization curve. Then, we discuss the theoretical mechanism of the double-peak structure of the magnetic susceptibility and the three-peak structure of the specific heat of the compound Cu-3(CO3)(2)(OH)(2), on which an elegant measurement was performed by Kikuchi [Phys. Rev. Lett. 94, 227201 (2005)]. Our computed results are consistent with the main characteristics of the experimental data. Meanwhile, we find that the double-peak structure of susceptibility can be found in several different kinds of spin interactions in the diamond chain. Moreover, a three-peak behavior is observed in the TMRG results of magnetic susceptibility. In addition, we perform calculations relevant for some experiments and explain the characteristics of these materials. (c) 2007 American Institute of Physics.

Syntheses and crystal structures of [Mn(H2O)(4)(bpy)]L center dot 4H(2)O, [Mn(H2O)(4)(bpy)]L ' center dot 4H(2)O (H2L = SUCCINIC ACID, H2L ' = FUMARIC ACID)

Reactions of freshly prepared M(OH)(2-2x)(CO3)(x) (.) yH(2)O (M = Mn, Zn) and 4,4'-bipyridine (bpy) with succinic acid (H2L) or famaric acid (H2L') in CH3OH-H2O afforded [Mn(H2O)(4)(bpy)]L (.) 4H(2)O, 1, [Mn(H2O)(4)(bpy)]L' (.) 4H(2)O, 2 and [Zn(H2O)(4)(bpy)]L (.) 4H(2)O, 3. The three coordination polymers are isostructural and consist of (1)(infinity)[M(H2O)(4)(bpy)(2/2)](2+) cationic chains, crystal H2O molecules and dicarboxylate anions (succinate or fumarate anions). Within the chains, the metal atoms are each octahedrally coordinated by four aqua oxygen atoms and two pyridyl nitrogen atoms from two 4,4'-bipyridine ligands. The crystal H2O molecules are hydrogen bonded to dicarboxylate anions to form ribbon-like anionic chains. The cationic and anionic chains are interconnected via hyqrogen bonds to generate a 3D network. Crystal data: 1 triclinic, P (1) over bar, a = 7.235(1), b = 7.749(2), c = 10.020(2) Angstrom, alpha = 79.95(3), beta = 88.79(3), gamma = 71.39(3)degrees, V = 523.9(2) Angstrom(3) and D-cal = 1.494 g cm(-3) for Z = 1; 2 triclinic, P (1) over bar, a = 7.127(1), b = 7.800(2), c = 9.945(2) Angstrom, alpha = 80.26(3), beta = 87.86(3), gamma = 72.69(3)degrees, V = 520.2(2) Angstrom(3) and D-cal = 1.498 g cm(-3) for Z = 1; 3 triclinic, P (1) over bar, a = 7.189(1), b = 7.764(2), c = 9.843(2) Angstrom, alpha = 79.16(3), beta = 87.80(3), gamma = 71.29(3)degrees, V = 510.9(2) Angstrom(3) and D-cal = 1.559 g cm(-3) for Z = 1.

Syntheses, crystal structures and properties of two Cu(II) coordination polymers: Cu(C3N2H4)(2)(HL)(2) andCU(C3N2H4)(2)L with C3N2H4 = imidazole, H2L = adipic acid

The reactions of freshly prepared Cu(OH)(2).xH(2)O and Cu(OH)(2-2y)(CO3)(y).zH(2)O precipitates with imidazole and adipic acid in CH3OH/H2O at pH = 5.4 yielded CU(C3N2H4)(2)(HL)(2) 1 and CU(C3N2H4)(2)L 2, respectively. Complex 1 consists of ribbon-like polymeric chains (1)(infinity)[CU(C3N2H4)(2)(HL)(4/2)], in which the octahedrally coordinated Cu atoms are doubly bridged by bis-monodentate hydrogen adipato ligands. The interchain N-H...O hydrogen bonding interactions are responsible for supramolecular assembly of the polymeric chains into open 3D frameworks and two-fold interpenetration of the resulting open frameworks completes the crystal structure of 1. Within complex 2, the Cu atoms are penta-coordinated to form CuN2O3 square pyramids and condensed into CU2N4O4 dimers, which are doubly bridged by twisted bis-monodentate adipato ligands into polymeric chains (1)(infinity)([CU(C3N2H4)(2)](2)L-4/2) with 4- and 18-membered rings progressing alternatively. The polymeric chains are assembled due to interchain N-H...O hydrogen bonding interactions. The thermal and magnetic behaviors of 1 and 2 is discussed.

Hydrothermal synthesis and structural characterization of a novel P-V-O layered compound [H(2)en](2)[H3O](6)[Co(H2O)(2)(VO)(8)(OH)(4)(PO4)8]

A new compound [H(2)en](2)[H3O](6)[Co(H2O)(2)(VO)(8)(OH)(4)(PO4)(8)] has been hydrothermally synthesized. Single crystal X-ray analysis indicates that this compound crystallizes in a monoclinic system, space group P2(1)/n with a=1.438 5(3) nm, b=1.012 2(2) nm, c=1.832 5(4) nm, beta=90.21degrees, V=2.668 2 (9) nm(3), Z = 2, D-c = 2.112 g/cm(3), R = 0.055, wR = 0.149 7, S = 1.037. The structure of [H(2)en](2)[H3O](6)[Co(H2O)(2)(VO)(8)(OH)(4)(PO4)(8)] is characterized by P-V-O layers constructed by [(VO)4 (OH)(2)(PO4)(4)](6-) non-symmetric units. The P-V-O layers are pillared by [Co(H2O)(2)](2+) group, resulting in the channels within which the protonated diaminoethane and H3O+ are located.

Supramolecular isomerism in zinc hydroxide coordination polymers with pyridine-2,4-dicarboxylic acid: Two polymorphs with centrosymmetric two-dimensional and acentric three-dimensional coordination networks

Reactions of Zn(BF4)(2) and pyridine-2,4-dicarboxylic acid (2,4-pydcH(2)) in the presence of 1,2-bis( 4-pyridyl) ethylene or 1,3-bis(4-pyridyl) propane under hydro(solvo) thermal conditions yielded two polymorphic metal-organic coordination polymers formulated as Zn-2(OH)(2)(2,4-pydc) (1 and 2). Polymorph 1 features a two-dimensional (2-D) layer-like structure that is constructed by 2,4-pydc ligands bridging between the Zn-OH-Zn double-chain units. Each single Zn-OH-Zn chain is composed of mu(2)-OH groups connecting trigonal bipyramidal and tetrahedral Zn centers. Polymorph 2 is a 3-D coordination polymer containing 2-D Zn-OH-Zn sheets that consist of mu(2)- and mu(3)-OH groups and trigonal bipyramidal Zn centers. The sheets are pillared by 2,4-pydc ligands to form an acentric structural architecture. 1 and 2 are rare examples that the two polymorphs exhibit a centrosymmetric 2-D coordination network and an acentric 3-D coordination network, respectively. The different structures lead to differences in photoluminescent properties and thermal stabilities for 1 and 2.

Synergistic extraction of rare earths by mixture of bis(2,4,4-trimethylpentyl)phosphinic acid and Sec-nonylphenoxy acetic acid

Synergistic extraction of trivalent rare earths (RE=Sc, Y, La, Gd, Yb) from hydrochloride medium using mixture of bis(2,4,4-trimethylpentyl)phosphinic acid (HL, Cyanex272) and Sec-nonylphenoxy acetic acid (HA, CA-100) in n-heptane has been studied. The synergistic enhancement coefficients were observed for La (1.30), Gd (1.97), Y (3.59), Yb (8.21) and Sc (14.41). The results indicated yttrium was extracted into n-heptane as YH(5)A(4)L(4) mixed species instead of Y(HL2)(3), Y(OH)(2)A(HA)(3) which were extracted by Cyanex272 and CA-100, respectively. A cation exchange mechanism was proposed and further clarified by IR spectra. The equilibrium constants, formation constants and thermodynamic functions such as Delta G, Delta H and Delta S were determined. The Cyanex272 + CA-100 system not only enhanced the extraction efficiency of RE but also improved the selectivities significantly. The mutual separation factors of these ions suggested the mixture system would be of practical value in extraction and separation of rare earths.

C-118 from fullerenols: Formation, structure and intermolecular nC(2) transfer reactions in mass spectrometry

In fast atom bombardment, two fullerenols C-60(OH)(x) (x=13-15) and C-60(OH)(x) (x-24-26) gave rise to a group of ions centered at C-118 with intervals of 24 mass units in the high mass region. In contrast, no such ions appeared in the mass spectra of pure C-60, C-70 and other fullerene derivatives such as C-60(C6H5)(10), under the same conditions. It is proposed that the pinacol rearrangement of C-60(OH)(2), resulting from partial rupture of the polyhydroxy molecules, produces C-59 with two carbon atoms bearing an unpaired electron, and that dimerization of this reactive intermediate is responsible for the formation of the predominant product C-118. An intermolecular nC(2) transfer process is used to explain the symmetrical abundance distribution of these product ions in the spectra of fullerenols.

Al2O3 : Cr3+ nanotubes synthesized via homogenization precipitation followed by heat treatment

Cr3+-doped NH4Al(OH)(2)CO3 nanotubes, templated by surfactant assemblies, were successfully synthesized via the homogenization precipitation method, and various crystallographic phase Al2O3:Cr3+ nanotubes were also obtained by postannealing at different temperatures. The characteristic R-1, R-2 doublet line transitions of ruby can be observed in the high crystalline alpha-Al2O3 nanotubes calcined at temperatures higher than 1200 degrees C. The results also indicate that the formation mechanism of the tubular nanostructures should result from the self-rolling action of layered compound NH4Al(OH)(2)CO3 under the assistance of the surfactant soft-template. The convenient synthetic procedure, excellent reproducibility, clean reactions, high yield, and fine quality of products in this work make the present route attractive and significant. Aluminum oxide nanotubes with high specific surface area could be used as fabricating nanosized optical devices doped with different elements and stable catalyst supports of metal clusters.

水热条件下钾长石碱性分解反应机理的实验研究

It is well known that our country is short of water-soluble potassium, but rich in insoluble potassium ores. Based on the work of the formers, using the orthogonal and monofactor experiments, the author optimized the production technology of micro-porous potassium silicon calcium mineral fertilizer by non-stirring hydrothermal chemical reaction when the alkaline earth booster CaO was available. The influences of temperature、time、reactant ratio and water-solid ratio on the dissolution rate of production’s elements were studied by orthogonal experiments, and the production technology was further optimized by monofactor experiments. By XRD、SEM、EDS and dissolving experiments, it was systematically studied that the effects of the reactant ratio、reaction time and reaction temperature on the properties of the production obtained by the hydrothermal reaction between KAlSi3O8 and CaO. The results showed that：when changing of the reaction condition, the reaction productions included tobermorite、 hibschite、α-C2SH and K2Ca(CO3)2; among which, K2Ca(CO3)2 was not the first production containing potassium, but K2Ca(CO3)2 was synthesized by the reaction among KOH、Ca(OH)2 and CO2. Whether the phase was synthesized was related to not only the reaction condition, but also their physicochemical properties; when the reaction condition was changed, the changes of different phases were different. The results of XRD and dissolution rate experiments explained the dissolution characteristic of every element of hydrothermal productions very well, and the relation between the dissolution rate of element and the phase of productions poured a good illumination on the production technology. The results of SEM and EDS showed that: hydrogarnet looked like spherical, and its surface was covered by some productions including K phase and Ca、Si phase; but the morphology of tobermorite was platy or lamellar or needlelike, and parts of Si in the structure of tobermorite were substituted by Al，and some K+ cations were inserted into the Ca interlayer of tobermorite at the same time. It was the first time that the interface between KAlSi3O8 and Ca(OH)2 was observed directly by SEM and EDS after the hydrothermal reaction, and the mechanism of hydrothermal reaction of KAlSi3O8 and Ca(OH)2 was further discussed. These results indicated that: the Ca-KAlSi3O8 intermediate compound was formed at first, and some K was released into the solution and KOH was produced at the same time; the C-S-H phase appeared before hydrogarnet, and then hydrogarnet was synthesized when the chemical reaction was carried on; if the reaction was carried on furthermore, α-C2SH、tobermorite and other C-S-H phases of different atom ratio appeared. The author found that the structure of KAlSi3O8 would be more drastically destroyed if there were some reactants, such as Ca(OH)2 which reacted with KAlSi3O8 and new phases were formed after the hydrothermal reaction between KAlSi3O8 and alkaline solution of equal ionic strength was finished. With the combination of calcination and hydrothermal reaction methods, the dissolution rate of products were greatly improved when the hydrothermal reaction was carried out after KAlSi3O8 and CaCO3 were calcined. Furthermore, the author has tentatively explored how to evaluate the effects of the differences of the activity of lime on the dissolution properties of hydrothermal products.

锰含量对LiNi_(0.85-x)Co_(0.15)Mn_xO_2结构及形貌的影响

采用共沉淀法先合成出氢氧化物前驱体Ni0.85-xCo0.15Mnx(OH)2,其中X=0、0.1、0.2和0.4,前驱体与Li2CO3在空气气氛中固相烧结制得正极材料LiNi0.85-xCo0.15MnxO2。用XRD、SEM研究了锰含量对材料结构和形貌的影响。研究发现,LiNi0.85Co0.15O2的X射线衍射图中存在微量第二相,而锰掺杂有利于减小反应过程中锂离子损失和镍离子占据锂位,容易形成有序层状结构材料。随着Mn离子替代Ni离子量的增加,晶胞参数a减小,晶胞参数c、c/a及I003/I104值增大。SEM结果表明前驱体和最终产物形貌均随锰含量增加颗粒均匀性增强,粒子尺寸变小,粒径分布变窄。

天然纳米结构材料——江苏盱眙凹凸棒土的特性及开发应用前景

本文对江苏盱眙凹凸棒土的样品进行比表面积测量,比表面积230m2／g。用X光衍射和X光荧光分析表明,此样品主相为坡缕石(Palygoskite),其分子式:(Mg,Al)5(Si,Al)8O20(OH)2?8H2O,这种颗粒的集合体具有特有的毡状结构,旧名山软木。显微结构棒晶长约1μm,直径约20nm,是天然纳米结构材料。本文指出,利用凹凸棒土比表面积大有很强的吸附性,开发出无毒粮食保鲜剂和无抗菌素的胃肠药;利用凹凸棒土一维针状纳米结构,对其表面进行改性,减弱凹凸棒土晶束之间的作用力,以利于在聚合物中分散,提高聚合物物理性能,开发凹凸棒土在聚合物材料上的应用。

BaF2替代BaO对钡镓锗酸盐玻璃光学性质的影响

在摩尔分数组成x(BaO),r(Ga2O),r(GeO2)为0．20，0．15,0．65的玻璃中，分别以摩尔分数0．05，0．10．0．15和0．20的BaF2替代BaO,研究了氟化物对玻璃折射率和光吸收性质的影响。结果表明，在玻璃中加入氟化物．玻璃折射率和色散降低，玻璃的紫外吸收边向短波侧迁移，而红外吸收边无明显变化。不含氟化物的氧化物玻璃中含有大量的OH基．这些OH基在2．24μm、2．97μm和4．23μm附近引起光吸收．在含氟化物的玻璃中，2．24μm的吸收峰消失，而2．97μm和4．23μm附近

理化因子对PSII内周天线CP43和CP47色素蛋白复合体结构与功能的影响

从菠菜叶绿体中分离纯化出PSII内周天线CP43及CP47色素蛋白复合物。通过利用光谱学手段 (吸收光谱、荧光光谱、CD光谱等)及生化技术(HPLC和电泳等)，研究了酸、碱、强光及高温等理化因子对其结构和功能的影响。结果如下： 1：酸和碱处理对CP43和CP47结构和功能的影响 1），酸、碱处理均使CP43和CP47红区主峰吸收降低，蓝区Soret带吸收降低，Soret带的附属带吸收增加，红区及蓝区吸收主峰均蓝移。酸处理时在542 nm及510 nm附近出现Pheo a的吸收峰，碱性处理时出现642 nm的吸收峰。酸、碱处理后CP43及CP47中绝大部分色素仍然结合在脱辅基蛋白上, 吸收光谱的变化源于结合态的色素而非游离色素。酸性条件下Chl a受到破坏变为Pheo a 使CP43及CP47失绿, 但Pheo a仍牢固地结合在脱辅基蛋白上，使CP43及CP47出现Pheo a的吸收峰。碱性条件下虽然绝大部分色素也结合在脱辅基蛋白上，但色素与蛋白之间的亲和力减弱，使其在进行PAGE电泳时从蛋白质上脱落。碱性条件下642 nm吸收峰的出现是OH- 与Chl a之间相互作用的结果，它需要蛋白质次级结构的变化，当蛋白质次级结构保持完整时或Chl a 分子被尿素分子包围时这种作用受到抑制。碱性条件下CP43及CP47中642 nm吸收峰的出现取决于Chl a与OH- 的相对量，同样在进行PAGE电泳时CP43中Chl a与脱辅基蛋白的分离也取决于Chl a与OH- 的相对量。 2），CP43中β-Car与Chl a之间的能量传递易于受碱的干扰，而在CP47中易于受酸的干扰。酸对CP43和CP47蛋白质次级结构的影响远小于碱的影响。酸和碱都显著地影响了Chl a分子所处的微环境并干扰了Chl a分子之间的激子相互作用。 3), 酸和碱以不同的方式影响CP43和CP47的光吸收、能量传递及蛋白质的次级结构。H+ 可以在不破坏蛋白质次级结构的情况下渗透到色素蛋白内部与Chl a反应而产生Pheo a，同时使β-Car和Chl a (或Pheo a) 之间的相对位置发生变化, 它们之间的能量传递受到干扰。OH- 首先破坏CP43和CP47中的氢键, 引起蛋白质解折叠, 使屏蔽在蛋白质内部的Chl a 暴露，进而与暴露的Chl a作用而将其皂化为叶绿素酸酯。随着蛋白质的去折叠, 其远紫外CD活性丧失, 色素所处的微环境受到干扰, β-Car和Chl a (或Chl a酸酯) 之间的相对位置发生改变, 因此β-Car和Chl a ( 或Chl a酸酯) 之间的能量传递也受到干扰。 4),酸或碱处理使CP43和CP47中Chl a 在进行HPLC时洗脱时间和洗脱峰面积发生改变, 但β-Car洗脱时间和洗脱峰的面积相对稳定。意味着酸碱处理并不破坏CP43及CP47中的β-Car。 2.强光照射对CP43结构和功能的影响 强光(1000 μmol E./m2.s)可以引起CP43中Chl a的漂白及蛋白质的降解，这种作用明显地被连二亚硫酸钠抑制。同样条件下,β-Car 的光吸收几乎不受光破坏的影响。 3.高温处理对CP43、CP47及其它PSII亚基降解的影响 用从菠菜叶片中分离出的PSII、OECC(放氧核心复合体)、去除33 kDa的OECC、RC-CP47(结合有CP47的反应中心复合体)、RC(反应中心复合体)、CP43及CP47等多亚基或单亚基色素蛋白复合体，研究这些复合体中各蛋白亚基在高温时的降解情况。结果发现PSII各蛋白亚基降解对温度的敏感性显著不同： CP43、D2、CP29、LHCII >D1、CP47 >> PsbO、PsbP、PsbQ及Cytb559 (α亚基)。

喷流-移动床垃圾衍生燃料热解燃烧特性研究

垃圾的处置已成为全球性环境问题。与填埋法相比，焚烧、热解和气化等热处理法具有减容、减量和能源化利用等优点。如何控制垃圾焚烧过程中HCI、二恶英和未燃尽碳氢化合物等污染物的排放也引起越来越多国家的关注。采用先热解（或气化）再气相燃烧的方法以及对垃圾预处理保持垃圾组成相对稳定的RDF技术是减少二次污染的有效手段。喷动技术能够用相对较小气量流化较粗大颗粒，是进行RDF热解的较佳选择。但RDF具有密度小、流动性差等特点，考虑减少空气量和改善RDF流动性，在喷动床中水平引入辅助气，称为"喷流一移动床"。本论文首先在室温下对喷流一移动床的流体力学特性进行了研究。结果表明，水平辅助气的引入可以降低中心最小喷动气速，调控喷泉高度，提高环流区颗粒的流动速度，增大颗粒的循环流量。在此基础上，根据先部分燃烧部分热解后气相燃烧以及自热型的原则，设计了下部为喷流一移动床热解室上部为气相燃烧室的两段式RDF热解燃烧反应器，并利用实验室内制备的RDF对该反应器的运行特性进行了评价。论文对喷动空气量和辅助空气量对热解室温度分布、气体分布，二次空气对燃烧室温度分布以及CO和NOx的释放特性的影响进行了研究，然后对有机氯（PVC）和无机氯（NaCI）产生Hcl特性、Ca（OH）2对HCI的脱除特性及机理进行了研究。实验结果表明，RDF可以成功地进行自热型的先热解后气相燃烧，通过改变空气／燃料比可以控制热解室温度，水平辅助气的引入可以使热解室轴向温度分布更加均匀，热解室中可以得到O2含量低于2v％热解气体，热解气体在燃烧室中能完全燃烧。二次空气能够控制燃烧室温度以及Co和NOx的排放。PVC中氯能产生较大数量的HCI外,NaCl同样也可生成HCl；温度对PVC生成HCI量的影响很小，而对NaCI却起主要影响作用。漓温不利于钙化物与HCI反应的进仃，同时CaC12在高温时与石英砂(SiO2)、水蒸汽反应产生HCl，因此Ca（OH）2的脱氯效率会降低。