Hydrothermal synthesis,crystal structure and physical properties of {[Gd(H2O)4(μ2-C6NO2H5)2Gd(H2O)4](μ3-C6NO2H4)2(ZnCl3)2} · 2H2O · 2Cl

A bimetallic 4f–3d tetranuclear complex {[Gd(H₂O)₄(μ₂-C₆NO₂H₅)₂Gd(H₂O)₄](μ₃-C₆NO₂H₄)₂(ZnCl₃)₂} · 2H₂O · 2Cl (1) has been synthesized via hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. Complex 1 is characterized by a tetranuclear Gd₂Zn₂ structure with the gadolinium and zinc atoms interconnected by isonicotinic acid ligands. The tetranuclear species of {[Gd(H₂O)₄(μ₂-C₆NO₂H₅)₂Gd(H₂O)₄](μ₃-C₆NO₂H₄)₂(ZnCl₃)₂} link to isolated chlorine ions and water molecules via π?π interactions and hydrogen bonds to yield a 3-D supramolecular framework. Photoluminescent investigation reveals that the title complex displays an emission in ultraviolet region. The solid-state diffuse reflectance spectra of 1 reveal the presence of a sharp optical gap of 3.66 eV.     

Structure stability and microwave dielectric properties of double perovskite ceramics – Ba2Mg1−xCaxWO6 (0.0 ≤ x ≤ 0.15)

The structure stability of double perovskite ceramics – Ba₂Mg_1?xCa_xWO₆ (0.0 ≤ x ≤ 0.15) has been studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Raman spectrometry in this paper. The microwave dielectric properties of the ceramics were studied with a network analyzer at the frequency of about 8–11 GHz. The results show that small amount of Ca substitution for Mg increases the Mg/CaO bond strength, and hence the stability of the double perovskite. But it cannot completely suppress the decomposition of Ba₂Mg_1?xCa_xWO₆ at high temperature. Although space group Fm?3m is adopted for all compositions, nonrandom distribution of Ca²⁺ and Mg²⁺ on 4b-site within the short range scale is observed due to their large cation size difference. Small level doping of Ca (x ≤ 0.1) increases the dielectric permittivity monotonically, but does not affect the Q × f value greatly. As expected, the substitution of Ca tuned the temperature coefficient of resonant frequency (τ_f value) from negative to positive value. Excellent combined microwave dielectric properties with ?_r = 20.8, Q × f = 120,729 GHz, and τ_f = 0 ppm/°C could be obtained for x = 0.1 composition. However the Q × f value degrades considerably when the sample was stored under ambient conditions for a long time.     

Syndiospecific styrene polymerization by (tert-BuC5H4)TiCl2(O-2,6-iPr2C6H3) – borate catalyst system

(^tBuC₅H₄)TiCl₂(O-2,6-ⁱPr₂C₆H₃) (2) exhibited relatively high catalytic activity for syndiospecific polymerization of styrene at 25 °C if both [PhMe₂NH]B(C₆F₅)₄ and a mixture of AlⁱBu₃/Al(n-C₈H₁₇)₃ were used as the cocatalyst. Effects of both organoaluminum and organoboron compounds were explored, and the effect of cocatalyst was different from that observed in 1-hexene polymerization catalyzed by Cp*TiCl₂(O-2,6-ⁱPr₂C₆H₃) (1). Resultant syndiotactic polystyrene possessed narrow molecular weight distribution under the optimized conditions, and the M_w values were unchanged during the time course.     

Phase evolution and chemical durability of Zr1-xNd xO2-x/2 (0 ≤ x ≤ 1) ceramics

A series of Zr_1-xNd _xO_2-x/2 (0 ≤ x ≤ 1) ceramics was prepared by solid-state reaction method. The effects of Nd content on the phase evolution were investigated. The chemical durability of resulting waste forms was also examined. The results show that the ceramics with x < 0.1 show monoclinic and cubic zirconia phase, with 0.2 ≤ x < 0.4 exhibit a single cubic phase, with 0.4 ≤ x ≤ 0.6 exhibit a single pyrochlore phase, with 0.6 < x < 0.8 exhibit a single cubic phase and remain cubic phases and hexagonal Nd₂O₃ when 0.8 ≤ x ≤ 1. The unit cell parameters of the Nd-doped zirconia samples increase as the Nd content increases. Moreover, the normalized element release rates of Nd element in Nd-doped zirconia ceramics firstly decrease with leaching time and almost no change after 21 days (∼0⁻⁶ g m⁻² d⁻¹), demonstrating its good chemical durability.     

Synthesis and negative thermal expansion properties of solid solutions Yb2−xLaxW3O12 (0 ≤ x ≤ 2)

A new series of rare earth solid solutions Yb_2?xLa_xW₃O₁₂ were successfully synthesized by the solid-state method. Effects of substituted ion lanthanum on the microstructures and thermal expansion properties in the resulting Yb_2?xLa_xW₃O₁₂ ceramics were investigated by X-ray diffraction (XRD), thermogravimetric analyzer (TGA), field emission scanning electron microscope (FESEM) and thermal mechanical analyzer (TMA). Results indicate that the structural phase transition of the Yb_2?xLa_xW₃O₁₂ changes from orthorhombic to monoclinic with increasing substituted content of lanthanum. The pure phases can form in the composition range of 0 ≤ x < 0.5 with orthorhombic structure and 1.5 < x ≤ 2 with monoclinic one. High lanthanum content leads to a low hygroscopicity of Yb_2?xLa_xW₃O₁₂. Negative thermal coefficients of the Yb_2?xLa_xW₃O₁₂ (0 ≤ x ≤ 2) also vary from ?7.78 × 10^?6 K^?1 to 2.06 × 10^?6 K^?1 with increasing substituted content of lanthanum.     

Mesoporous CuO/TixZr1 − xO2 catalysts for low-temperature CO oxidation

Mesoporous CuO/Ti_xZr_1 − xO₂ catalysts were prepared by a surfactant-assisted method, and characterized by N₂ adsorption/desorption, TEM, XPS, in-situ FTIR and H₂-TPR. The catalysts exhibited high specific surface area (S_BET = 241 m²/g) and uniform pore size distribution. XPS and in-situ FTIR displayed that Cu⁺ and Cu²⁺ species coexisted in the catalysts. The CuO/Ti_xZr_1 − xO₂ catalysts presented obviously higher activity in CO oxidation reaction than the CuO/TiO₂ and CuO/ZrO₂ catalysts. Effect of molar ratios of Ti to Zr and calcination temperature on catalytic activity was investigated. The CuO/Ti_0.6Zr_0.4O₂ catalyst calcined at 400 °C exhibited excellent activity with 100% CO conversion at 140 °C.     

Thermal expansion and thermal conductivity of SmxZr1−xO2−x/2 (0.1 ≤ x ≤ 0.5) ceramics

A study was conducted of the effect of additions of samarium oxide on the thermal expansion and thermal conductivity of zirconium oxide for thermal barrier coatings. Sm_xZr_1?xO_2?x/2 (0.1 ≤ x ≤ 0.5) ceramic powders synthesized with a chemical-coprecipitation and calcination method were sintered at 1873 K for 15 h. Structures of the synthesized powders and sintered ceramics were identified by X-ray diffractometer. The morphologies of ceramic powders were observed by transmission electron microscope. The thermal expansion coefficients and thermal diffusion coefficients of Sm_xZr_1?xO_2?x/2 ceramics were studied with a high-temperature dilatometer and a laser flash diffusivity technique from room temperature to 1673 K. The thermal conductivity was calculated from thermal diffusivity, density and specific heat of bulk ceramics. Sm_0.1Zr_0.9O_1.95 ceramics consists of both monoclinic and tetragonal structures. However, Sm_0.2Zr_0.8O_1.9 and Sm_0.3Zr_0.7O_1.85 ceramics only exhibit a defect fluorite structure. Sm_0.4Zr_0.6O_1.8 and Sm_0.5Zr_0.5O_1.75 ceramics have a pyrochlore-type lattice. With the increase of Sm₂O₃ content, the linear thermal expansion of Sm_xZr_1?xO_2?x/2 ceramics increases except for Sm_0.1Zr_0.9O_1.95. The thermal conductivities of Sm_xZr_1?xO_2?x/2 ceramics ranged from 1.41 at 873 K to 1.86 W m^?1 K^?1 at room temperature in a test temperature range of room temperature to 1673 K, and the results can be explained by phonon scattering mechanism.     

Heterogeneous oxidation of 2-octanol on 5 wt%Pt–1 wt%Bi/Carbon catalyst

The low activity of 5%Pt–1%Bi/Carbon for the oxidation of 2-octanol at atmospheric pressure and 343 K was investigated. Using solvents such as heptane and p-xylene, it was shown that the reaction rates decrease dramatically shortly after the start of the reaction due to poisoning by product adsorption. Hence this work investigates the effect of using different solvent mixtures on the oxidation reaction of 2-octanol with 5%Pt–1%Bi/Carbon. Mixtures with different volumetric ratios of heptane and dioxane were investigated to find the best composition capable of effectively removing the adsorbed amphiphilic ketone. It is apparent that the reaction rate is correlated with the adsorption coefficient of ketone on the catalyst, such that the maximum reaction rate occurs at the lowest ketone adsorption coefficient, corresponding to a concentration of 16–18%v/v dioxane. A model based on a Langmuir–Hinshelwood mechanism has been successfully fitted to the experimental rates.     

Crystal structure,mixture behavior,and microwave dielectric properties of novel temperature stable (1 − x)MgMoO4 − xTiO2 composite ceramics

Novel temperature stable MgMoO₄–TiO₂ microwave dielectric ceramics were prepared by a solid state reaction process at low temperature (950 °C). As TiO₂ content increases, the relative permittivity increases while the Q × f value decreases, and the variation mechanisms are proposed, respectively. The temperature coefficient of resonant frequency (τ_f) shifts to the positive direction as TiO₂ is added. The mixture mechanisms of τ_f value for two-phase composite materials are supposed. A near-zero τ_f value (3.2 ppm/°C) is obtained when x = 0.3, with ε_r = 9.13 ± 0.03 and Q × f = 11,990 GHz. The 0.7MgMoO₄–0.3TiO₂ composites are considered to be appropriate as a low temperature co-fired ceramic material for microwave wireless communication applications.     

Frequency and temperature dependent electrical properties of Ni0.7Zn0.3CrxFe2−xO4 (0 ≤ x ≤ 0.5)

Series of the ferrite samples with a chemical formula Ni_0.7Zn_0.3Cr_xFe_2?xO₄ (x = 0.0–0.5) were prepared by a sol–gel auto-combustion method and annealed at 600 °C for 4 h. The prepared samples have the cubic spinel structure with no impurity phase. As the Cr³⁺ content x increases, the unit cell dimensions decrease with an increase in Cr³⁺ content x. The crystallite size is decreases from 37 nm to 21 nm as the Cr³⁺ content increases from x = 0.0 to 0.5. Resistivity increases whereas dielectric constant decreases with an increase in Cr³⁺ content x. Maxima in the dielectric loss tangent versus frequency appear when the frequency of the hopping charge carriers coincides with the frequency of the applied alternating field. Dielectric constant and dielectric loss tangent increases with increase in temperature. Saturation magnetization of sintered samples showed higher values as compared to as-prepared sample. Curie temperature deduced from AC susceptibility data decreases with increasing x.     

2，2，6，6－四氯环己酮的研制

阐述了以环己酮为原料液相法制备２，２，６．－四氯环己酮的方法，就催化剂的种类、用量、加料速度、水的存在等诸多因素对反应的影响进行了讨论。     

Synthesis,structure of a coordination polymer: {Na2[Zn(C2O4)1.5H2PO4] · 2H2O}n

A phosphatooxalate compound {Na₂[Zn(C₂O₄)_1.5H₂PO₄] · 2H₂O}_n 1 was synthesized under hydrothermal condition and characterized by single-crystal X-ray diffraction, IR spectroscopy, thermal gravimetric analysis (TGA) and fluorescent spectroscopy. X-ray single-crystal analysis revealed that its structure was a new mixed inorganic–organic ligand supramolecular framework building up through multilayer assembly.     

A novel uranyl complex UO2(tci)(C3H5N2) · H2O: Synthesis,crystal structure and characterization

Reaction of uranium oxynitrate hexahydrate with tris(2-carboxyethyl)isocyanurate (tciH₃) in acidic aqueous solution (pH ～4–5) yields the compound UO₂(tci)(C₃H₅N₂) · H₂O. X-ray diffraction shows that the uranyl ion is in a hexagonal bipyramid structure. Uranium ion in the complex is found to be ligated with three chelating COO^? groups at the equatorial plane, two oxygen atoms linking to uranium atom formed the vertical axis. The complex has the layered topology structure in the space. The thermal analysis verifies the component and the structure of the complex.     

K2SiF6沉淀容量法测定H2SiF6和Na2SiO3

Ｋ_２ＳｉＦ_６沉淀容量法测定Ｈ_２ＳｉＦ_６和Ｎａ_２ＳｉＯ_３朱光华（江西第二机床厂，３４３４００）１前言装饰性滚镀铬、尺寸复合镀铬都要用Ｈ２ＳＯ４和Ｈ２ＳｉＦ６作催化剂。由于含有Ｈ２ＳｉＦ６的镀铬溶液可采用较高的电流密度，电流效率较高１８～２５％，光...     

A Michael-type reaction between acrylato ions and ethylenediamine coordinated to Ni(II). Synthesis,crystal structure and magnetic properties of [Ni2(EDDP)2(H2O)2] · 2H2O (H2EDDP = ethylenediamine-N,N-dipropionic acid)

The reaction between NiCO₃ · Ni(OH)₂, acrylic acid and ethylenediamine in a 2:4:1 molar ratio affords the binuclear complex, [Ni₂(EDDP)₂(H₂O)₂] · 2H₂O 1. The organic ligand, EDDP^2? (the dianion of the ethylenediamine-N,N-dipropionic acid ligand), results from the addition of one amine group to the carbon–carbon double bonds of two acrylato ions. The crystal structure of 1 consists of neutral centrosymmetric entities, with the nickel ions connected by two carboxylato groups, each one acting as a monoatomic bridge. The intramolecular Ni?Ni distance is 3.212 Å. The metal ions exhibit an octahedral geometry. The cryomagnetic investigation of 1 reveals an antiferromagnetic coupling of the nickel(II) ions (J = ?21.8 cm^?1, H = ?JS_Ni1S_Ni2).     

Organic–inorganic hybrid oxides: Structure and magnetic properties of [{Cu(terpy)}2Mo6O17(H2O)(O3PCH2NH2CH2PO3)2] · H2O,a bimetallic oxide constructed from novel {Mo6O17(H2O)(O3PCH2NH2CH2PO3)2}4− clusters

The hydrothermal reaction of MoO₃, CuSO₄ · 5H₂O, 2,2′:6′:2″-terpyridine (terpy) and bis-N,N-(methylphosphonic acid) amine (H₂O₃PCH₂NHCH₂PO₃H₂) provided blue crystals of the bimetallic oxide [{Cu(terpy)}₂Mo₆O₁₇(H₂O)(O₃PCH₂NH₂CH₂PO₃)₂] · H₂O (1 · H₂O). The three-dimensional structure of 1 is constructed from {Mo₆O₁₇(H₂O)(O₃PCH₂NH₂CH₂PO₃)₂}⁴⁻ clusters linked through {Cu(terpy)}²⁺ subunits. The cluster consists of three pairs of edge-sharing {MoO₆} octahedra linked through corner-sharing interactions into a {Mo₆O₆} ring. One phosphonate ligand spans the diameter of the ring, bridging four molybdenum sites and leaving at a pendant {PO} group at each terminus. The second diphosphonate ligand exploits one {–PO₃} unit to cap the hexamolybdate ring and bridge all six molybdenum sites while the second {–PO₃} terminus bridges two molybdenum sites, leaving a pendant {PO} unit. Crystal data: C₃₄H₄₅Cu₂Mo₆N₈O₃₅P₄: monoclinic, P2₁/n, a = 11.9431(7) Å, b = 17.382(1) Å, c = 27.524(2) Å, β = 90.429(1)°, V = 5713.7(6) Å³, Z = 4, D_calc = 2.270 g cm⁻³, R₁ = 0.0466.