35Cl NQR in N3P3Cl4Ph2 and N3P3Cl4(NMe2)2

³⁵Cl NQR has been investigated in two cyclotriphosphazene derivatives N₃P₃Cl₄Ph₂ and N₃P₃Cl₄(NMe₂)₂. The observed frequencies are assigned to the various chlorines and the temperature variation of the NQR frequencies studied in the range from 77 K to 300 K. The results are analysed using the Bayer-Kushida-Brown approach. Torsional (librational) frequencies are found to fall in the range 10–25 cm^?1 and are found to be only slightly temperature dependent.     

Xα scattered wave calculations of the ionisation energies of N3P3F6 and N4P4F8

Ionisation energies have been calculated for N₃P₃F₆ and N₄P₄F₈ with the overlapping sphere version of the Xα scattered wave method and with the inclusion of a vacacy sphere for the interior of each PN ring. Experimental energies are calculated to within 1 eV on average for both sets of calculations, but the spacings of the levels are reproduced better with the vacancy sphere model.     

Electronic structure, galvanomagnetic and magnetic properties of the bismuth subhalides Bi4I4 and Bi4Br4

Two bismuth-rich subhalides, Bi₄Br₄ and Bi₄I₄, featuring extended quasi one-dimensional metallic fragments in their structures, have been investigated. The gas-phase technique of crystal growth has been refined for obtaining large (up to 5 mm long) single crystals. Electronic structure calculations on three-dimensional structures of both compounds have been performed (DFT level, hybrid B3LYP functional), predicting a semiconducting behavior for both compounds, with an indication of possible directional anisotropy of electric conductivity. Galvanomagnetic (resistance, magnetoresistance, Hall effect, thermopower) and magnetic (temperature and field dependence of magnetization) properties have been measured experimentally. Both compounds are found to be diamagnetic, room-temperature semiconductors with n-type conductivity. While Bi₄Br₄ demonstrates a typical case of one dimensionality, the difference in magnetoresistivity between Bi₄Br₄ and Bi₄I₄ indicates some weak interactions between isolated bismuth metallic fragments within the bismuth substructures.     

Pressure dependence of 35Cl NQR in hexachloro- (N3P3Cl6) and octachloro- (N4P4Cl8) cyclophosphazenes

High pressure studies of ³⁵Cl NQR in the hexachlorocyclophosphazene N₃P₃Cl₆ and in the K- and T-forms of octachlorocyclophospha     

Coordination environment of [UO2Br4] in ionic liquids and crystal structure of [Bmim]2[UO2Br4]

The complex formed by the reaction of the uranyl ion, UO₂²⁺, with bromide ions in the ionic liquids 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][Tf₂N]) and methyl-tributylammonium bis(trifluoromethylsulfonyl)imide ([MeBu₃N][Tf₂N]) has been investigated by UV–Vis and U L_III-edge EXAFS spectroscopy and compared to the crystal structure of [Bmim]₂[UO₂Br₄]. The solid state reveals a classical tetragonal bipyramid geometry for [UO₂Br₄]²⁻ with hydrogen bonds between the Bmim⁺ and the coordinated bromides. The UV–Vis spectroscopy reveals the quantitative formation of [UO₂Br₄]²⁻ when a stoichiometric amount of bromide ions is added to UO₂(CF₃SO₃)₂ in both Tf₂N-based ionic liquids. The absorption spectrum also suggests a D_4h symmetry for [UO₂Br₄]²⁻ in ionic liquids, as previously observed for the [UO₂Cl₄]²⁻ congener. EXAFS analysis supports this conclusion and demonstrates that the [UO₂Br₄]²⁻ coordination polyhedron is maintained in the ionic liquids without any coordinating solvent or water molecules. The mean U–O and U–Br distances in the solutions, determined by EXAFS, are, respectively, 1.766(2) and 2.821(2) Å in [Bmim][Tf₂N], and, respectively, 1.768(2) and 2.827(2) Å, in [MeBu₃N][Tf₂N]. Similar results are obtained in both ionic liquids indicating no significant influence of the ionic liquid cation either on the complexation reaction or on the structure of the uranyl species.     

Ionization energies and electronic structure of N3P3Cl6 as determined by UV photoelectron spectroscopy and the Xα scattered wave method

Ionization energies have been measured for N₃P₃Cl₆ by He I photoelectron spectroscopy and they are compared with values calculated with the overlapping-spheres version of the Xα scattered wave method; the average discrepancy is less than 0.4 eV. The wavefunctions and associated charge distributions are used for assessing models of ring π bonding, and comparisons are made with previous calculations for N₃P₃F₆ and N₄P₄F₈. The calculated charge distributions are related to trends in measured core electron binding energies, and have important implications for the interpretation of Faraday effect measurements on cyclic phosphazenes.     

Vapour-liquid equilibrium data for the systems C2H6 + N2, C2H4 + N2, C3H8 + N2, and C3H6 + N2

High pressure vapour-liquid equilibrium data for the C₂H₆ + N₂, C₂H₄ + N₂, C₃H₈ + N₂, and C₃H₆ + N₂ systems are presented. The data are obtained isothermally in the range from 200 K to 290 K. For each point of data, temperature, pressure and liquid and vapour phase mole fractions are measured.Values for the vapour phase mole fractions are calculated from the obtained pressure, temperature and liquid phase mole fractions. The calculated values are compared with the experimental results, and it is found that the average mean deviation between calculated and experimental mole fractions is less than 0.009 for the systems considered in this work.     

Preparation and performance comparison of LiMn2O3.95Br0.05 and LiMn2O3.95Br0.05/SiO2 cathode materials for lithium-ion battery

LiMn₂O_3.95Br_0.05 and LiMn₂O_3.95Br_0.05/SiO₂ cathode composites for lithium-ion battery are prepared by solid-state reaction methods. The crystalline structures of the as-synthesized samples are investigated by X-ray diffraction and transmission electron microscope; at the same time, the electrochemical performances are tested by cyclic voltammetry and galvanostatic cycling. The results reveal that the sample of LiMn₂O_3.95Br_0.05/SiO₂ has more excellent electrochemical performance than the sample of LiMn₂O_3.95Br_0.05. It delivers an initial discharge capacity of 145.3 mA h g⁻¹ at ambient temperature, and 138.9 mA h g⁻¹ at the higher temperature of 55 °C with good capacity retention with the voltage range of 3.0–4.35 V (vs. Li) at a current density of 0.5 C; while the sample of LiMn₂O_3.95Br_0.05 only deliver initial discharge capacity 136.5 mA h g⁻¹ at ambient temperature, and 119.2 mA h g⁻¹ at 55 °C in the same conditions; in addition, the rate performance of LiMn₂O_3.95Br_0.05/SiO₂ is excellent too, so the SiO₂ layer has improved the electrochemical behaviors of LiMn₂O_3.95Br_0.05 availably.     

Crystal structure and magnetic properties of two new cobalt selenite halides: Co5(SeO3)4X2 (X=Cl, Br)

Two new isostructural cobalt selenite halides Co₅(SeO₃)₄Cl₂ and Co₅(SeO₃)₄Br₂ have been synthesized. They crystallize in the triclinic system space group P−1 with the following lattice parameters for Co₅(SeO₃)₄Cl₂: a=6.4935(8) Å, b=7.7288(8) Å, c=7.7443(10) Å, α=66.051(11)°, β=73.610(11)°, γ=81.268(9)°, and Z=1. The crystal structures were solved from single-crystal X-ray data, R1=3.73 and 4.03 for Co₅(SeO₃)₄Cl₂ and Co₅(SeO₃)₄Br₂, respectively. The new compounds are isostructural to Ni₅(SeO₃)₄Br₂.Magnetic susceptibility measurements on oriented single-crystalline samples show anisotropic response in a broad temperature range. The anisotropic susceptibility is quantitatively interpreted within the zero-field splitting schemes for Co²⁺ and Ni²⁺ ions. Sharp low-temperature susceptibility features, at T_N=18 and 20 K for Co₅(SeO₃)₄Cl₂ and Co₅(SeO₃)₄Br₂, respectively, are ascribed to antiferromagnetic ordering in a minority magnetic subsystem. In isostructural Ni₅(SeO₃)₄Br₂ magnetically ordered subsystem represents a majority fraction (T_N=46 K). Nevertheless, anisotropic susceptibility of Ni₅(SeO₃)₄Br₂ is dominated at low temperatures by a minority fraction, subject to single-ion anisotropy effects and increasing population of S_z=0 (singlet) ground state of octahedrally coordinated Ni²⁺.     

Crystal structure and magnetic properties of Co2TeO3Cl2 and Co2TeO3Br2

The crystal structures of the two new synthetic compounds Co₂TeO₃Cl₂ and Co₂TeO₃Br₂ are described together with their magnetic properties. Co₂TeO₃Cl₂ crystallize in the monoclinic space group P2₁/m with unit cell parameters a=5.0472(6) Å, b=6.6325(9) Å, c=8.3452(10) Å, β=105.43(1)°, Z=2. Co₂TeO₃Br₂ crystallize in the orthorhombic space group Pccn with unit cell parameters a=10.5180(7) Å, b=15.8629(9) Å, c=7.7732(5) Å, Z=8. The crystal structures were solved from single crystal data, R=0.0328 and 0.0412, respectively. Both compounds are layered with only weak interactions in between the layers. The compound Co₂TeO₃Cl₂ has [CoO₄Cl₂] and [CoO₃Cl₃] octahedra while Co₂TeO₃Br₂ has [CoO₂Br₂] tetrahedra and [CoO₄Br₂] octahedra. The Te(IV) atoms are tetrahedrally [TeO₃E] coordinated in both compounds taking the 5s² lone electron pair E into account. The magnetic properties of the compounds are characterized predominantly by long-range antiferromagnetic ordering below 30 K.     

BiOCl0.5Br0.5/BiPO4双层异质结薄膜光催化剂的一步电化学法制备及性能

采用一步电化学法在金属 Bi板上成功制备了 Bi OCl_0.5Br_0.5/Bi PO₄双层异质结薄膜,并通过多种表征手段对薄膜的晶型结构、元素组成及化合价、形貌和尺寸特征、吸光性能和荧光强度进行了表征。结果表明,制备得到的复合薄膜呈现出上层为梭子状的 Bi PO₄颗粒层分散在下层为 Bi OCl_0.5Br_0.5固溶体层的双层结构。这样的双层膜排列顺序使得光生电子和空穴在不同组分之间的界面电场作用下分别向薄膜两侧流动,促进光致载流子的分离,提高了 Bi OCl_0.5Br_0.5/Bi PO₄复合薄膜的光催化活性。活性测试结果表明,在模拟太阳光照射 120 min 后,Bi OCl_0.5Br_0.5/Bi PO₄复合薄膜对苯酚的降解率达到了 99.97%,是相同条件下制备的 Bi OCl/Bi PO₄和 Bi O...     

Influence of coordination on N-H X hydrogen bonds. Part II. Zn(NH3)2Br2 and Ni(NH3)2X2 (X is Cl and Br)

Microcrystalline samples of Zn(NH₃)₂Br₂ and Ni(NH₃)₂X₂ (X is Cl⁻ and Br⁻) have been investigated from 100 to 293 K using X-ray diffraction and IR spectroscopy measurements (range 400–4000 cm⁻) performed with isotopically dilute (5% deuterated) samples. Values of Δν(ND)/ΔT for all compounds hint at the existence of hydrogen bonds. Zn(NH₃)₂Br₂ shows The dynamics of ammonia molecules even at 100 K, and no indications are apparent that dynamic disorder of ammonia molecules takes place in Ni(NH₃)₂X₂ (X is Cl⁻ and Br⁻). A comparison between octahedrally coordinated ammoniates [Ni(NH₃)₆]Br₂, Ni(NH₃)₂Br₂ and [Zn(NH₃)₆]Br₂ with tetrahedrally coordinated ones [Zn(NH₃)₂Br₂] leads to the conclusion that the lower coordination number increases the strength of the hydrogen bonds. Because this effect is small, it is not possible to separate the influence of the type of coordinating ions for one coordination number from the influence of the coordination number itself.     

Vibrational relaxation of N2(A3Σu+,υ = 1, 2,3) by CH4 and CF4

N₂(A, υ = 0-3) produced by the Ar(³P_0,2) + N₂ reaction and detected by laser-induced fluorescence undergoes rapid, stepwise vibrational relaxation but slow electronic quenching with added CH₄ or CF₄. Rate constants, k_Q^υ, of 1.5, 3.1, and 5.0 × 10^?12 cm³ s^?1 are measured for Q = CH₄, υ = 1-3, and 0.47, 1.8, and 5.5 × 10^?12 cm³ s^?1 for Q = CF₄, υ = 1-3, with ≈±20% accuracy (1σ). Information is also obtained for the unrelaxed, relative υ populations.     

A hybrid material based on [Mo6Br14] inorganic cluster units and [BEDO-TTF] organic monocationic radicals: Synthesis, structure and properties of (BEDO-TTF)2Mo6Br14(PhCN)4

The first charge transfer salt based on non- dimerized [BEDO-TTF]⁺ monocationic radical (BEDO-TTF=bis(ethylenedioxy)tetrathiafulvalene) associated with [Mo₆Br₁₄]²⁻ cluster anions has been synthesized by conventional electro-oxidation and characterized by single crystal X-ray diffraction, UV-VIS-NIR absorption and magnetic susceptibility measurements. (BEDO-TTF)₂Mo₆Br₁₄(PhCN)₄ crystallizes in the monoclinic system, space group P2₁/n, a=10.414(4) Å, b=21.711(7) Å, c=15.958(5) Å, β=93.65(3)°, V=3601(2) Å³, Z=2, R₁=0.0578, wR₂=0.0731. The structure of this hybrid compound is built up from a [BEDO-TTF]⁺ and PhCN (benzonitrile) organic framework in which are hosted the [Mo₆Br₁₄]²⁻ inorganic cluster units. It results in non- dimerized [BEDO-TTF]⁺ cations that exhibit a paramagnetic behavior characteristic of one unpaired electron.     

纯相和镍取代的Co_3O_4尖晶石催化剂用于N_2O直接分解(英文)

A series of NixCo1-xCo2O4(0 ≤ x ≤ 1) spinel catalysts were prepared by the co-precipitation method and used for direct N2O decomposition. The decomposition pathway of the parent precipitates was characterized by thermal analysis. The catalysts were calcined at 500 °C for 3 h and characterized by powder X-ray diffraction, Fourier transform infrared, and N2 adsorption-desorption. Nickel cobaltite spinel was formed in the solid state reaction between NiO and Co3O4. The N2O decomposition measurement revealed significant increase in the activity of Co3O4 spinel oxide catalyst with the partial replacement of Co2+ by Ni2+. The activity of this series of catalysts was controlled by the degree of Co2+ substitution by Ni2+, spinel crystallite size, catalyst surface area, presence of residual K+, and calcination temperature.     

Anomalous low-temperature behavior of the Co dimers in the oxo-halide CoSb2O3Br2

We report the synthesis, crystal structure determination, magnetic and low-temperature structural properties of a new cobalt antimony oxo-bromide. CoSb₂O₃Br₂ crystallizes in the triclinic crystal system, space group P−1, with the following lattice parameters: a=5.306(3) Å, b=7.812(4) Å, c=8.0626(10) Å, α=88.54(3)°, β=82.17(3)°, γ=80.32(4)°, and Z=2. The crystal structure was solved from single crystal X-ray data and refined on F², R₁=3.08. The structure consists of layers made up by three building blocks, [CoO₄Br₂], [SbO₃Br], and [SbO₃] that are connected via edge- and corner-sharing so that structural Co-Co dimers are formed. The layers have no net charge and are only weakly connected by van der Waals forces to adjacent layers. Above ∼25 K the magnetic susceptibility is independent of the magnetic field and can be very well described by a Curie-Weiss law. Below 25 K the susceptibility passes through a maximum and decreases again that is typical for the onset of long-range antiferromagnetic correlations. Long-range antiferromagnetic ordering is observed below T_N∼9 K indicating substantial inter-dimer exchange coupling between Co-Co dimers within the layers. However, according to the heat capacity results only a minute fraction of the entropy is associated with the long-range ordering transition. The phonon anomalies observed for T<6 K in Raman scattering and an anomaly in the specific heat point to a structural instability leading to a loss of inversion symmetry at lowest temperatures.     

On the INDO calculations of N32− and N4− free radicals

?-tensors as well as anisotropic and isotropic hyperfine coupling constants have been calculated for the N₃^2? and N₄^? free radicals. The adequacy of the INDO method is discussed in relation with the results of a previous ab initio calculation.     

Crystal structure and energy band and optical properties of phosphate Sr3P4O13

A single crystal of the compound Sr₃P₄O₁₃ has been found and the crystal structure has been characterized by means of single crystal X-ray diffraction analysis. The compound crystallizes in triclinic system and belongs to space group . It builds up from SrO₇ polyhedra and P₄O₁₃⁻⁶ anions and has a layered structure, and the Sr atoms are located in the interlayer space. The absorption and luminescence spectrum of Sr₃P₄O₁₃ microcrystals have been measured. The calculated results of crystal energy band structure by the DFT show that the solid state of Sr₃P₄O₁₃ is an isolator with direct band gap. The calculated total and partial density of states indicate that the top valence bands are contributions from P 3p and O 2p states and low conduction bands mostly originate from Sr atomic states. The calculated optical response functions expect that the Sr₃P₄O₁₃ is a low refractive index, and it is possible that the Sr₃P₄O₁₃ is used to make transparent material between the UV and FR light zone.     

Comparative high-pressure study and chemical bonding analysis of Rh3Bi14 and isostructural Rh3Bi12Br2

The binary compound Rh₃Bi₁₄ was synthesized from the elements. The compound is isostructural with Rh₃Bi₁₂Br₂, crystallizes with the orthorhombic space group Fddd (no. 70) and lattice parameters a=6.8959(15) Å, b=17.379(3) Å, c=31.758(6) Å. The crystal structure consists of a three-dimensional (3D) framework of edge-sharing cubes and square antiprisms (RhBi_8/2). It is closely related to the intermetallic compound RhBi₄, in which two Y-like frameworks of antiprisms interpenetrate. In Rh₃Bi₁₄ and Rh₃Bi₁₂Br₂, additional bismuth and bromine anions, respectively, fill the channels of the 3D polyhedral framework formed by covalently bonded rhodium and bismuth atoms. High-pressure X-ray powder diffraction data from synchrotron measurements of Rh₃Bi₁₄ and Rh₃Bi₁₂Br₂ indicate a high stability of both compounds in the investigated range from ambient pressure to ca. 30 GPa at ambient temperature.