Studies on the System ZnO-V2O5-Fe2O3 Reactivity of ZnFe2O4 Towards ZnV2O6

Studies on the reactivity of ZnFe₂O₄ towards ZnV₂O₆ revealed that in the solid state the phases interact in a molar ratio of 1:3 to form a new compound, to which the molecular formula Zn₂FeV₃O₁₁ was assigned. The compound melts congruently at 825±5°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phase relations in subsolidus area of ZnO-V2O5-Fe2O3 system

Phase equilibria in subsolidus area in the ZnO-V₂O₅-Fe₂O₃ system have been investigated over the whole concentration range of the oxides. The components of this system form two compounds: Zn₂FeV₃O₁₁ and Zn₃Fe₄(VO₄)₆. A solidus area projection onto the component concentration triangle plane of the ZnO-V₂O₅-Fe₂O₃ system has been constructed using DTA and XRD methods. 11 subsidiary subsystems can be distinguished in this system. Melting temperatures of mixtures of solid phases coexisting at equilibrium in each of subsidiary subsystems were determined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and selected properties of a new solid solution in the Zn2FeV3O11–Mg2FeV3O11 system

The binary Zn₂FeV₃O₁₁?CMg₂FeV₃O₁₁ system has been studied by XRD, DTA, IR, and SEM methods. A new continuous substitution solid solution with the formula Zn_2?x Mg _x FeV₃O₁₁ has been obtained by high-temperature synthesis. The DTA investigations were used to choose the heating temperatures as well as for determination of thermal stability of the new triclinic phase. The influence of the degree of Mg²⁺ ion incorporation on the unit cell volume as well as on the position of the IR absorption bands of the solid solution have been determined. The morphology of crystals of the new phase is presented.     

Eine weitere Oxovanadat-Phase mit Granatstruktur: Ca5Mg3ZnV6O24

An Additional Oxovanadate Phase with Garnet Structure: Ca₅Mg₃ZnV₆O₂₄ Single crystals of Ca₅Mg₃ZnV₆O₂₄ were prepared by solid state reactions some degree below the melting point of the reaction mixture. It crystallizes with cubic symmetry, space group T-I4 3 d with a = 12.429 Å, Z = 4. The crystal structure is nearly related to the Garnet structure showing Ca²⁺ within distorted cubes (C.N. = 8) of O^2? on a partly unfilled position. the octahedra position are occupied by Mg²⁺ and Zn²⁺ statistically.     

Zur Kristallchemie von Ba3In2Zn5O11. Ein tOxoindat/zinkatsol;zinkat mit Zn10O20- und In4O16-Makropolyedern und erstmals O2− in tetraedrischer Koordination durch Zn2+

On the Crystal Structure of Ba₃In₂Zn₅O₁₁. An Oxoindate/zincatesol;zincate with Zn₁₀O₂₀ and In₄O₁₆ Macropolyhedra with Zn²⁺ in Tetrahedral Coordination by O^2? Ba₃In₂Zn₅O₁₁ was prepared for the first time by a flux technique and investigated by single crystal X-ray work. It crystallizes with cubic symmetry, space group T-F4 3m, a = 13.3588 Å, Z = 8. Zn²⁺ show tetrahedral coordination by O^2?, forming Zn₁₀O₂₀ macropolyhedra. In addition the nZn/Osol;O part of the crystal structure is made up of Zn₁₀O₂₀ parts. Edge connection of four InO₆ octahedra results in In₄O₁₆ groups. The crystal structure will be shown and discussed.     

(Zn1-xMnx)C2O4·2H2O在空气中的热分解动力学研究

用热分析（TG-DTG/DTA）、X射线衍射（XRD）技术和透射电镜（TEM）研究了固态物质Zn_1-xMn_xC₂O₄•2H₂O在空气中热分解的过程。热分析结果表明，Zn_1-xMn_xC₂O₄•2H₂O在空气中分两步分解，其失重率与理论计算失重率相吻合。 XRD和TEM结果表明，Zn_1-xMn_xC₂O₄•2H₂O分解的最终产物为Zn_1-xMn_xO,其颗粒大小约为10-13 nm。在非等温条件下对Zn_1-xMn_xC₂O₄•2H₂O的热分解动力学进行了分析。用Friedman法和Flynn-Wall-Ozawa(FWO)法求取了分解过程的活化能E，并用多元线性回归给出了可能的机理函数。Zn_1-xMn_xC₂O₄•2H₂O两步热分解的活化能分别为155.7513 kJ/mol 和215.9397 kJ/mol。     

Synthese und Strukturuntersuchung von CoV2O6

Synthesis and Structure Determination of CoV₂O₆ The hitherto unknown compound CoV₂O₆ was prepared by solid state reaction in single crystal form. The X-ray single crystal investigations lead to the space group C? C2 with a = 9.256, b = 3.508, c = 6.628 Å, β = 111.55°. CoV₂O₆ is isotypic with ZnV₂O₆ or β-CdV₂O₆. It shows an octahedral coordination of Co²⁺ and constructional units like V₂O₅.     

Ein neues Kupfercobaltboratoxid mit isolierten B2O5-Baugruppen: Cu2Co(B2O5)O

On a New Copper Cobalt Borate Oxide with Isolated B₂O₅ Units: Cu₂Co(B₂O₅)O Single crystals of a new compound with the empirical formula Cu₂CoB₂O₆ were obtained by using a B₂O₃ flux technique. X-ray single crystal technique led to a new structure type. Cu₂CoB₂O₆ crystallizes monoclinic, space group C-P2₁/c (No. 14); a = 3.2250(6); b = 14.847(1); c = 9.1171(6) Å; β = 93.67°; Z = 4. All metal sites are octahedrally coordinated and form a two dimensional framework consisting of edge sharing octahedra ribbons. In addition one observes isolated B₂O₅-units and oxygen which is not coordinated to boron. The far relation to the crystal structure of the mineral Warwickite is illustrated.     

Ein neues Praseodymniobat Pr2Nb11O30

A New Praseodymiumniobate Pr₂Nb₁₁O₃₀ By chemical vapor transport (T₂ → T₁, T₂ = 950 °C, T₁ = 900 °C, 3 d) of a mixture of PrOCl and Nb₂O₅ (1 : 1) using 5 mg NH₄Cl as transport agent we obtained the new compound Pr₂Nb₁₁O₃₀. The crystal structure determination [a = 6.2325(5) Å, c = 32.3677(36) Å, Z = 2, 1631 independent I₀, 69 parameters, R1 = 2.07%] shows CN = 8 (twofold capped octahedrally) for Pr, CN = 7 (pentagonal bipyramidally) for Nb(1,2) and CN = 6 (octahedrally) for Nb(3). The structure is closely related to that of Cu₅Ta₁₁O₃₀.     

Zur Kenntnis von Zn4Ta2O9

About the New Compound Zn₄Ta₂O₉ The hitherto unknown compound Zn₄Ta₂O₉was prepared by high temperature reaction (CO₂-LASER technique). The X-ray investigation of single crystal shows monoclinic symmetry (space group C? C2/c) with a = 15.002(6), b = 8.954(1), c = 10.345(4)Å and β = 93.64(3)°. Zn₄Ta₂O₉ consists of a Zn/O-network with incorporated one-dimensional TaO₆-chains. The edge connected TaO₆-octahedrals are occupied by Ta⁵⁺ and 0.5 Zn²⁺ respectively. The crystal chemistry of this compound in respect to other Zn-oxotantalates are discussed.     

K2Zn3O4 und Rb2Zn3O4, zwei neue Oxozincate mit Gerüststruktur [1]

K₂Zn₃O₄ and Rb₂Zn₃O₄, Oxozincates with Framework Structure For the first time single crystals of K₂Zn₃O₄ were obtained by heating mixtures of the binary oxides (K: Zn = 2.2:3) in sealed Ag- or Pt-capsules at 800°C (5 w). Powder of this colourless and moisture-sensitive oxide was prepared analogously at 500°C. It crystallizes monoclinic, space group C2/c with a = 1482.7(2), b = 637.3(1), c = 571,9(1) pm, β = 102.79(1)°, Z = 4, d_x = 4.265 g/cm³, d_pyk = 4.00 g/cm³. The crystal structure was determined from four-circle diffractometer data (MoKα, 730 unique hkl) and refined to R = 5.9%, R_w = 6.4%. It shows a Zn₃O₄ framework which consists of SiS₂-like chains [ZnO_4/2] connected by puckered layers of [ZnO_3/3]. The crystal structure can be derived from a cubic closet packing of O^2? and K⁺. Effective Coordination Numbers and the Madelung Part of Lattice Energy (MAPLE) are calculated. Rb₂Zn₃O₄ was prepared from the binary oxides at 400°C (colourless hygroscopic powder). According to powder data it crystallizes isostructural to K₂Zn₃O₄ with a = 1523.5(4), b = 649.8(2), c = 574.0(2) pm, β = 101.43(3)°, Z = 4, d_x = 5.141 g/cm³, d_pyk = 5.20 g/cm³.     

Clewlike ZnV2O4 Hollow Spheres: Nonaqueous Sol–Gel Synthesis,Formation Mechanism,and Lithium Storage Properties

Hollow ZnV₂O₄ microspheres with a clewlike feature were synthesized by reacting zinc nitrate hexahydrate and ammonium metavanadate in benzyl alcohol at 180 °C for the first time. GC–MS analysis revealed that the organic reactions that occurred in this study were rather different from those in benzyl alcohol based nonaqueous sol–gel systems with metal alkoxides, acetylacetonates, and acetates as the precursors. Time‐dependent experiments revealed that the growth mechanism of the clewlike ZnV₂O₄ hollow microspheres might involve a unique multistep pathway. First, the generation and self‐assembly of ZnO nanosheets into metastable hierarchical microspheres as well as the generation of VO₂ particles took place quickly. Then, clewlike ZnV₂O₄ hollow spheres were gradually produced by means of a repeating reaction–dissolution (RD) process. In this process, the outside ZnO nanosheets of hierarchical microspheres would first react with neighboring vanadium ions and benzyl alcohol and also serve as the secondary nucleation sites for the subsequently formed ZnV₂O₄ nanocrystals. With the reaction proceeding, the interior ZnO would dissolve and then spontaneously diffuse outwards to nucleate as ZnO nanocrystals on the preformed ZnV₂O₄ nanowires. These renascent ZnO nanocrystals would further react with VO₂ and benzyl alcohol, ultimately resulting in the final formation of a hollow spatial structure. The lithium storage ability of clewlike ZnV₂O₄ hollow microspheres was studied. When cycled at 50 mA g^?1 in the voltage range of 0.01–3 V, this peculiarly structured ZnV₂O₄ electrode delivered an initial reversible capacity of 548 mAh g^?1 and exhibited almost stable cycling performance to maintain a capacity of 524 mAh g^?1 over 50 cycles. This attractive lithium storage performance suggests that the resulting clewlike ZnV₂O₄ hollow spheres are promising for lithium‐ion batteries.     

Criegee自由基CH2O2与H2O反应机理及动力学的理论研究

在6-311＋G(2d,2p)水平下, 采用密度泛函理论(DFT)的B3LYP方法, 研究了Criegee 自由基CH₂O₂与H₂O的反应. 结果表明反应存在三个通道: CH₂O₂＋H₂O®HOCH₂OOH (R1); CH₂O₂＋H₂O®HCO＋OH＋H₂O (R2); CH₂O₂＋H₂O®HCHO＋H₂O₂ (R3), 各通道的势垒高度分别为43.35, 85.30和125.85 kJ/mol. 298 K下主反应通道(R1)的经典过渡态理论(TST)与变分过渡态理论(CVT)的速率常数k^TST与k^CVT均为2.47×10^－17 cm³•molecule^－1•s^－1, 而经小曲率隧道效应模型(SCT)校正后的速率常数k^CVT/SCT为 5.22×10^－17 cm³•molecule^－1•s^－1. 另外, 还给出了200～2000 K 温度范围内拟合得到的速率常数随温度变化的三参数Arrhenius方程.     

Synthese und Kristallstruktur von Ba6Lu4Zn10O22 mit [OBa6]-Oktaedern

On the Synthesis and Crystal Structure of Ba₆Lu₄Zn₁₀O₂₂ with [OBa₆] Octahedra Single crystals of Ba₆Lu₄Zn₁₀O₂₂ have been prepared by high temperature reactions and investigated by X-ray techniques. This compound is isotypic to Ba₃In₂Zn₅O₁₁ and the first member of the Rare Earth elements. Ba₆Lu₄Zn₁₀O₂₂ crystallizes with cubic symmetry, space group T-F4 3m, a = 13.452(1) Å and Z = 4. Zn²⁺ shows a tetrahedral, Lu³⁺ an octahedral and Ba²⁺ a three-fold capped trigonal prismatic coordination by O^2?. The ZnO₄ tetrahedra and LuO₆ octahedra are forming macro polyhedra of the type Zn₁₀O₂₀ and Lu₄O₁₆. A discussion is given for the Ba₆O₃₃ and Ba₆O₄₂ groups.     

Multistep oligometal complexation of the macrocyclic tris(N2O2) hexaoxime ligand

A macrocyclic oxime ligand H₆L, which has an O₆ cavity surrounded by three N₂O₂ chelate sites, was synthesized and the multistep oligometal complexation behavior was investigated. Upon complexation with zinc(II), the H₆L ligand afforded two kinds of hexanuclear complexes, L₂Zn₆ then LZn₆. Each of the complexation steps proceeded highly efficiently. In the latter complex, a Zn₃(μ₃‐OH) unit was incorporated into the trimetalated ligand, LZn₃. The integrated N₂O₂ chelate coordination sites provide a unique environment for a homometallic complex. The different nature of the peripheral N₂O₂ sites and the central O₆ site is particularly suitable for the selective formation of heterometallic complexes. Complexation with the zinc(II) ion in the presence of alkaline earth (Ca and Ba) or rare earth (La, Eu, Lu) metal ions afforded the heterotetranuclear complexes LZn₃M (M=Ca, Ba, La, Eu, Lu), in which zinc(II) and ion M occupied the N₂O₂ and O₆ sites, respectively. Titration experiments showed that the heterometallic complexes LZn₃Ca and LZn₃Ba were converted into the homometallic complex LZn₆ whereas LZn₃La was not. As a result, the binding affinity in the central O₆ site of the LZn₃ unit is apparently in the order of Ca²⁺, Ba²⁺3(μ₃‐OH)3+. This difference in the affinities of metal ions as well as the ionic sizes makes the novel conversion efficient, particularly in the case of the three‐step conversion from H₆L to H₂LZn₂Ba, LZn₃Ba, then LZn₆.     

Effect Nd2O3 content on electrochemical performance of polyaniline/Nd2O3 composites

Polyaniline/neodymium(III) oxide (PANI/Nd₂O₃) composites were synthesized by in situ chemical oxidative polymerization method, and the new electrode materials were used for supercapacitor. The composites were characterized physically by scanning electron microscope (SEM), Fourier transform infrared spectra (FTIR) and X‐ray diffraction (XRD). SEM, IR and XRD results showed the existence of interactions between PANI and Nd₂O₃. The electrochemical capacitance performance of the composites was investigated by cyclic voltammetry, galvanostatic charge–discharge tests and ac impedance spectroscopy with a three‐electrode system in 6 M KOH solution. Cyclic voltammetry and galvanostatic charge/discharge tests proved that the addition of Nd₂O₃ enhanced the capacitance of the composites. However, the conductivity of the composites decreases with increasing the amount of Nd₂O₃. Electrochemical impedance tests manifest that the charge‐transfer resistance of the composites is smaller than that of the pure PANI, which indicates the addition of Nd₂O₃ could lower resistance and facilitate the charge transfer of the active materials. All results support that Nd₂O₃ has a significant contribution to the performance of PANI and makes the composites have more active sites for faradiac reaction and larger specific capacitance than pure PANI. Copyright © 2014 John Wiley & Sons, Ltd.     

Rate Coefficients of the Reactions of CN and NCO with O2 and NO2 at 296 K

The rate coefficients of the reactions of CN and NCO radicals with O₂ and NO₂ at 296 K: (1) CN + O₂ → products; (2) CN + NO₂ → products; (3) NCO + O₂ → products and (4) NCO + NO₂ → products have been measured with the laser photolysis-laser induced fluorescence technique. We obtained k₁ = (2.1 ± 0.3) × 10^?11 and k₂ = (7.2 ± 1.0) × 10^?11 cm³ molecule^?t s^?1 which agree well with published results. As no reaction was observed between NCO and O₂ at 297 K, an upper limit of k₃ < 4 × 10^?17 cm³ molecule^?1 S^?1 was estimated. The reaction of NCO with NO₂ has not been investigated previously. We measured k₄ = (2.2 ± 0.3) × 10^?11 cm³ molecule^?1 s^?1 at 296 K.     

Synthesis,Crystal Structure,and Properties of a New Lead Aluminum Fluoride Borate,Pb6AlB2O7F7

A new compound, Pb₆AlB₂O₇F₇, was synthesized from the PbF₂/B₂O₃ flux system, which is the first compound found in the PbF₂/Al₂O₃/B₂O₃ system. It crystallizes in the orthorhombic system, space group Cmca (No. 64) with unit cell parameters a = 11.649(7) Å, b = 18.300(11) Å, c = 6.394(4) Å, Z = 4. The crystal structure of Pb₆AlB₂O₇F₇ contains the group [Pb₆BO₁₁F₁₀] as basal building unit, which connects with each other forming two‐dimensional _∞[Pb₆BO₁₁F₁₀] layers, whereas aluminum atoms are filled in the interlayers. The IR spectrum further confirms the presence of BO₃ groups. The calculated band structures and the density of states of Pb₆AlB₂O₇F₇ suggest that its indirect gap is 2.968 eV. The DSC analysis and X‐ray diffraction technique prove that Pb₆AlB₂O₇F₇ is a congruent‐melting compound.     

The structures of lithium inserted metal oxides: Li2FeV3O8

Neutron diffraction powder profile analysis has been used to determine the structure of Li₂FeV₃O₈. The compound is prepared from FeV₃O₈, which has the VO₂(B) structure type, by a lithium insertion reaction employing n-BuLi. Only minimal distortion of the host lattice occurs on Li insertion. The Li ions occupy five coordinate square pyramidal sites with an average LiO bond distance of 2.04 Å. These five coordinate sites occur commonly in the capped perovskite cavities of crystallographic shear structures based on ReO₃.     

Darstellung und Kristallstruktur von K6[Al2O6] und Rb6[Al2O6]

Preparation of Crystal Structure of K₆[Al₂O₆] and Rb₆[Al₂O₆] Colourless single crystals of K₆[Al₂O₆] have been prepared from intimate mixtures of KAlO₂ and K₂O (550°C, 90 d). The structure determination from four-circle diffractometer data (MoKα , 742 I_o(hkl), R = 2.2%, R_w = 2.1%) confirms the space group C2/m with Z = 2; a = 698.25 pm, b = 1 103.54 pm, c = 646.49 pm, β = 102.49°. Colourless single crystals of hitherto unknown Rb₆[Al₂O₆] have been prepared from intimate mixtures of RbAlO₂ and Rb₂O (520°C, 120 d). The structure determination from four-circle diffractometer data (MoKα , 1 240 I_o(hkl)) results in the residual values R = 7.2%, R_w = 4.9%; space group C2/m; a = 725.92 pm, b = 1 143.33 pm, c = 678.06 pm, β = 104.05°; Z = 2. K₆[Al₂O₆] and Rb₆[Al₂O₆] are isostructural with K₆[Fe₂O₆]. A characteristic structure unit is the anion [Al₂O₆]^6? consisting of two edge-sharing [AlO₄] tetrahedra. Effective Coordination Numbers (ECoN), Mean Fictive Ionic Radii (MEFIR), the Madelung Part of Lattice Energy (MAPLE) and the Charge Distribution (CHARDI) are calculated and discussed.