非平衡晶化控制水滑石晶粒尺寸

本文采用非平衡晶化法通过在晶化后期补加原料合成了一系列不同晶粒尺寸的水滑石（LDH）样品,研究表明：非平衡晶化法可在一定范围内调控LDH的粒径,所合成的LDH样品组成稳定,晶体结构完整。     

Sol–gel synthesis of tetragonal ZrO2 nanoparticles stabilized by crystallite size and oxygen vacancies

In this letter, we present a facile route to produce metastable tetragonal zirconia (ZrO₂) nanoparticles via pH-controlled precipitation of dilute zirconyl nitrate dihydrate [ZrO(NO₃)₂·2H₂O] solution in liquid NH₃ under ambient conditions and calcination at 500 °C for 2 h. The phase pure tetragonal ZrO₂ nanoparticles are obtained at pH 9. The effect of pH on metastable phase stabilization in precipitated ZrO₂ nanoparticles is demonstrated with the help of XRD, SEM/EDX, and X-ray photoelectron spectroscopy techniques. The stability of tetragonal ZrO₂ phase is attributed to the smaller crystallite size and greater oxygen deficiency in phase-pure tetragonal ZrO₂.     

Preparation, characterization, and catalytic activity of rare earth metal oxide nanoparticles

In present study, a series of rare earth metal oxide (CeO₂, Pr₂O₃, and Nd₂O₃) nanoparticles have been prepared by sol–gel route using Ce(NO₃)₃·6H₂O, Pr(NO₃)₃·6H₂O and Nd(NO₃)₃·6H₂O, and citric acid as precursor materials. Powder X-ray diffraction, scanning electron microscopy, and transmission electron microscopy are employed to characterize the size and morphology of the nano oxide particles. The particles are spherical in shape and the average particle size is of the order of 11–30 nm. Their catalytic activity was measured on the thermal decomposition of ammonium perchlorate and composite solid propellants (CSPs) by thermogravimetry (TG), TG coupled with differential thermal analysis (TG–DTA), and ignition delay measurements. The ignition delays and activation energies are found to decrease when rare earth metal oxide nanoparticles were incorporated in the system. Addition of metal oxide nanoparticles to AP led to shifting of the high temperature decomposition peak toward lower temperature and the burning rate of CSPs was also found to enhance. However, E _a activation energy for decomposition was also found to decrease with each catalyst.     

Surfactant Assisted Hydrothermal Synthesis of Superparamagnetic ZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Efficient Visible-Light Photocatalyst for the Degradation of Organic Pollutant

Super paramagnetic ZnFe₂O₄ nanoparticles were prepared by a surfactant assisted (ethylamine) hydrothermal method along with heat treatment. The nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, high resolution scanning electron microscopy, Transmission electron microscopy, vibrating sample magnetometer and diffuse reflectance spectra technique. From the analyses, influence of calcination temperature on the structural, vibrational, morphological, magnetic and optical properties of ZnFe₂O₄ nanoparticles were investigated. The ZnFe₂O₄ nanoparticles with an average particle size of 17 nm showed high photocatalytic activity in the degradation of methylene blue (90 %). This work demonstrates that ZnFe₂O4 can be used as a potential monocomponent in visible-light photocatalysis for the degradation of organic pollutants. Furthermore, the products were super paramagnetic and could be conveniently separated within 15 min and recycled by using simple magnet, which is very beneficial for the degradation of organic pollutants.     

Synthesis of a magnetic micro/nano Fe x O y -CeO2 composite and its application for degradation of hexachlorobenzene

A micrometer-sized nanostructured, magnetic, ball-like Fe _x O _y -CeO₂ composite was synthesized through an ethylene-glycol mediated process. The synthesized samples were characterized by scanning electron microscopy combined with energydisperse X-ray analysis, transmission electron microscopy and X-ray powder diffraction. In the synthesis system, polyethylene glycol (PEG) and urea were found to play significant roles in the formation of the micrometer-sized spherical architecture of the precursor. The details of morphology and particle size could be changed with the initial concentration of Fe(NO₃)₃·9H₂O and Ce(NO₃)₃·6H₂O as the reactants. The magnetic Fe _x O _y -CeO₂ composite with a similar morphology was readily obtained by calcination from the precursor. The characterization of transmission electron microscopy showed the calcined ball-like architecture was a highly porous structure consisting of many nanoparticles. Because of the micrometer-sized nanostructure and the multi-components as well as the magnetism, the as-obtained Fe _x O _y -CeO₂ composite showed better activity and potentially easy recovery for the harmless degradation of hexachlorobenzene (HCB).     

Controlling the morphology of yttrium oxide through different precursors synthesized by hydrothermal method

Y₂O₃ sheets, rods, needles and tubes were synthesized from three precursors through hydrothermal reactions followed by calcination. The phase distribution and decomposition behaviors of the three precursors, Y₂(OH)_5.14(NO₃)_0.86·H₂O, Y₄O(OH)₉(NO₃) and hexagonal Y(OH)₃, were investigated. The reaction temperature and initial pH value during the hydrothermal reaction showed great influence on the shape and particle size of the products. The precursors were converted to Y₂O₃ particles with the retained original morphology of the precursors.     

COMPLEXES OF MOLYBDENUM(V) AND LANTHANUM(III) WITH 2′,2″′-(2,6-PYRIDINEDIYLDIETHYLIDENE)-DIOXAMOHYDRAZIDE (H2DAPSOX)

Abstract

In a template synthesis from ethanolic solution of MoOCl₃, 2,6-diacetylpyridine (dap), and semioxamazide (sox), in the molar ratio 1:1:2, a dimeric molybdenum(V) complex [Mo₂O₂(H₂dapsox)₂]Cl₆ · 4H₂O (where H₂dapsox = 2′,2″′-(2,6-pyridinediyldiethylidenedioxa-mohydrazide) was obtained. In a similar reaction, starting from La(NO₃)₃ · 6H₂O, the complex [La(H₂dapsox)(NO₃) _x ](NO₃)_3-x · 1/2EtOH (x = 1,2), having coordination number 9, was obtained. In the latter complex two NO₃ Groups were bidentately coordinated in the solid state, but only one in the solution.

Besides [Mo₂O₂(TPP)₂] (TPP = tetraphenylporphyrin), the molybdenum(V) complex [Mo₂O₂ (H₂dapsox)₂]Cl₆ · 4H₂O is the only other known example of a dimeric μ-oxodimolybdenum(V) species that is paramagnetic (μ = 0.95 BM). One of the Mo atoms has pentagonal bipyramidal coordination, and the other pentagonal pyramidal coordination. In aqueous solution a rare example of a pentagonal pyramidal ion [MoO(dapsox)]⁺ is presumably present. Solution EPR spectra (at 77K) cannot be related to either of the two known types of Mo(V) species based on the extent of g anisotropy. The substances also were characterized by IR and electronic spectroscopy, and by thermal analysis.     

大比表面积钛黑颜料的制备和表征

本文首次通过pH值控制沉淀法制备前驱物丁二酸钛肼复盐, 并进一步热分解制备大比表面积钛黑颜料-黑色钛氧化物。通过比表面积(BET)、电子能谱(EDS)、X射线光电子能谱分析(XPS)、X射线粉末衍射(XRD)、场发射扫描电子显微镜(HRSEM)、物理吸附仪、激光粒度仪和Color i5型台式分光测色仪对黑色钛氧化物进行了表征, 确定了黑色钛氧化物的组成为2TiO₂·Ti₂O₃, 其表面积为53.854 4 m²·g^-1。并考察了酸源、水合肼用量、酸钛比、反应时间、pH、NaOH浓度和煅烧温度等各种反应参数对黑色钛氧化物的颗粒尺寸、分布均匀性和黑色度的影响。用元素分析仪和等离子体光谱仪测定了前驱物组成, 确定其组成为[Ti(C₄H₄O₄)₂]_0.85·2Ti₂O₃·6N₂H₄·3H₂O, 并探讨了黑色钛氧化物形成机理, 为新型混合价材料黑色钛氧化物的制备提供重要参考依据。     

Chlorination as a means for changing the composition of iron-containing nanoparticles in a polyethylene matrix

Mössbauer spectroscopy, X-ray powder diffraction, and transmission electron microscopy were used to study the reactions of Fe₃O₄ or FeCl₂ · 4H₂O nanoparticles stabilized in a polyethylene (HPPE) matrix with gaseous chlorine and hydrogen chloride. These reactions produce FeCl₂ · 2H₂O nanoparticles, which retain the particle size and distribution over the HPPE matrix intrinsic to precursor nanoparticles. We propose chemical modification of iron-containing nanomaterials as a means for manufacturing iron(II) chloride nanoparticles.     

Study on the obtaining of cobalt oxides by thermal decomposition of some complex combinations,undispersed and dispersed in SiO<Subscript>2</Subscript> matrix

In order to obtain cobalt oxides nanoparticles we have used the thermal decomposition of some carboxylate type precursors. These precursors were obtained by the redox reaction between cobalt nitrate and ethylene glycol, either bulk or dispersed in silica matrix. The redox reaction takes place by heating the Co(NO₃)₂·6H₂O-C₂H₆O₂ solution or the Si(OC₂H₅)₄-Co(NO₃)₂·6H₂O-C₂H₆O₂ gels. Thermal analysis of the Co(NO₃)₂·6H₂O-C₂H₆O₂ solution and Si(OC₂H₅)-Co(NO₃)₂·6H₂O-C₂H₆O₂ gels allowed us to establish the optimal value for the synthesis temperature of the carboxylate precursors. By fast heating of the solution Co(NO₃)₂·6H₂O-C₂H₆O₂, the redox reaction is immediately followed by the decomposition of the precursor, which represents an autocombustion process. The product of this combustion contains CoO as unique phase. We have obtained a mixture of CoO and Co₃O₄ by annealing the synthesized carboxylate compounds for 2 h at 400°C. With longer annealing time (6 h), we have obtained Co₃O₄ as unique phase. The XRD study of the crystalline phases resulted by thermal decomposition of the precursors embedded in silica matrix, showed that the formation of Co₂SiO₄ and Co₃O₄, as unique phases, depends on the thermal treatment.     

Synthesis and Characterization of H3PW12O40 and H3PMo12O40 Nanoparticles by a Simple Method

In this study H₃PW₁₂O₄₀·9H₂O and H₃PMo₁₂O₄₀·6H₂O (HPA) particles were changed into nano forms by heat-treatment in an autoclave as a simple, repaid, inexpensive and one step method. The particle size of these nanoparticles was around 25 nm. The as-synthesized nanostructures were characterized by dynamic light scattering, X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and inductively coupled plasma analyzer. Thermal stability of nanoparticles was surveyed by thermal gravimeter analyse. Acidity of prepared nanoparticles was investigated by pyridine adsorption method. Results showed rising acidity by declining particle size of HPA.     

Crystallization process of lanthanum-substituted bismuth titanate synthesized by a facile sol–gel method

We present a facile sol–gel route to synthesize lanthanum-substituted bismuth titanate (BLT). The chemical reactions and crystallization process of this method using the initial materials of bismuth subnitrate [4BiNO₃(OH)₂·BiO(OH)], lanthanum nitrate [La(NO₃)₃·6H₂O] and tetrabutyl titanate [Ti(C₄H₉O)₄] were investigated by thermogravimetric and differential thermal analysis, IR spectroscopy, gas chromatography/mass spectrometry, Raman spectroscopy and XRD. The evaporation of the dissolved CO₂ in the amorphous BLT matrix is associated with the crystallization of BLT. The BLT gel is pure BLT perovskite when calcination temperature is higher than 500 °C. The grain size of the obtained nanoparticles ranges from 15 to 82 nm. The Arrhenius curve is obtained from the representation of the reduced sizes with respect to the calcination temperature. The activation energy of grain growth in BLT nanoparticles is 0.36 eV, which shows a rapidly growth process in the temperature range of 500–850 °C.     

纳米复合氧化物CuO·SnO2的制备与结构表征

0引言由于纳米材料在热学、电学、磁学、光学等方面具有的独特性能,使其在新功能材料、催化、光电能转换等许多领域引起了人们浓厚的研究兴趣[1]。近年来,纳米催化剂对固体推进剂的燃烧性能影响研究已成为热点[2～9]。但是由于固体推进剂燃烧的特殊性,要求不仅提高燃速,而且降低压力指数,因此并非所有的纳米催化剂都是有效的。大量实践已证明[10],多种催化剂的复合使用,将可获得远远优于单一催化剂的效果。研究已发现[11],纳米复合氧化物是由多种元素复合而成,使其在结构和性能上得到互补和叠加,加上纳米粒子所具有的各种效应,从而产生独特…     

无机过氧化物的研究——Ⅱ.从粉状白钨酸制备过氧钨酸钕

应用倒滴加法制备的粉状白钨酸,制备了两个新的不同组成的过氧钨酸钕:NH_4NdW_2(O_2)_5(OH)_2·4H_2O(1)和NH_4NdW_3(O_2)_3O_8·6H_2O(2)并对化合物的一些性质进行了表征。     

Tetranitratogoldsäure, (H5O2)[Au(NO3)4]·H2O: Synthese,Kristallstruktur und thermisches Verhalten des ersten sauren Nitrates des Goldes

Tetranitratogold(III) Acid, (H₅O₂)[Au(NO₃)₄]·H₂O: Synthesis, Crystal Structure, and Thermal Behaviour of the First Acidic Nitrate of Gold Yellow single crystals of (H₅O₂)[Au(NO₃)₄]·H₂O grow upon cooling of a solution of Au(OH)₃ in conc. nitric acid. The crystal structure contains (monoclinic, C2/c, Z = 4, a = 1214.5(2), b = 854.4(1), c = 1225.7(2) pm, β = 117.75(1)°, R_all = 0.0331) the Au³⁺ ion in coordination of four monodentate NO₃^— ligands. The [Au(NO₃)₄]^— units are linked by H₅O₂⁺‐ions. Significant hydrogen bonding is observed in the crystal structure between the H₅O₂⁺ ions and the H₂O molecules. The thermal analysis reveals a five step decomposition leading to elemental gold.     

Mehrkernige Kobaltkomplexe. IV. Darstellung und Struktur von [(papd)Co(O2)Co(papd)](S2O6)(NO3)2 · 4 H2O1)

Polynuclear Cobalt Complexes. IV. Preparation and Structure of [(papd)Co(O₂)Co(papd)](S₂O₆)(NO₃)₂ · 4 H₂O The binuclear peroxo complex [(papd)Co(O₂)Co(papd)](S₂O₆)(NO₃)₂ · 4 H₂O I crystallizes in the triclinic space group P1 . Lattice constants are a = 9.405(4), b = 9.270(4), c = 12.218(6)Å, α = 89.58(5), β = 99.08(6), γ = 114.79(5)° for Z = 1. The binuclear cation has a center of symmetry, so the Co? O? O? Co unit is planar. Three chelate rings have a common plane, the ligand configuration is δ.     

Synthesis,Characterization and Thermal Decompositions Studies of Some Malates Coordination CompoundsI. iron nickel compounds

The thermal behaviour of three coordination compounds, potential precursors of nickel ferrite [Fe₂Ni(C₄H₄O₅)_2.5(OH)₂]NO₃·5H₂O,[Fe₂Ni(C₄H₈O₃N₂)₄](NO₃)₈·24H₂O and (NH₄)[Fe₂Ni(C₄H₄O₅)₃(OH)₃]·3H₂O has been investigated to evaluate their suitability as precursors for nickel ferrite. For a complete and reliable assignment of the thermal transformations, the isolable solid intermediates and end products were characterized by IR, X-ray diffraction and Mössbauer investigations. A decomposition scheme is proposed.     

Coordination Reaction of Alanine with Neodymium(III) and Erbium(III) Nitrate. Thermochemical study

The solid-state coordination reaction: Nd(NO₃)₃·6H₂O(s)+4Ala(s) → Nd(Ala)₄(NO₃)₃·H₂O(s)+5H₂O(_l) and Er(NO₃)₃·6H₂O(s)+4Ala(s) → Er(Ala)₄(NO₃)₃·H₂O(s)+5H₂O(l) have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products in 2 mol L^–1 HCl solvent of these two solid-solid coordination reactions have been measured using a calorimeter. From the results and other auxiliary quantities, the standard molar formation enthalpies of [Nd(Ala)₄(NO₃)₃·H₂O, s, 298.2 K] and[Er(Ala)₄(NO₃)₃·H₂O, s,298.2 K] at 298.2 K have been determined to be Δ_f H _m ⁰ [Nd(Ala)₄(NO₃)₃·H₂O,s, 298.2 K]=–3867.2 kJ mol^–1, and Δ_f H _m ⁰ [Er(Ala)₄(NO₃)₃·H₂O, s, 298.2 K]=–3821.5 kJ mol^–1. This revised version was published online in August 2006 with corrections to the Cover Date.     

Redox reactions between metal nitrates and polyols with the formation of nanopowders

The reduction of metal nitrates (Cu(NO₃)₂ · 6H₂O, AgNO₃, and Ni(NO₃)₂ · 6H₂O) by polyols under hydrothermal conditions at temperatures of 150–250°C was studied. The possibility of synthesizing copper, silver, and nickel powders with average particle sizes of 10 to 150 nm depending on the concentration of initial reagents, the temperature, and the nature of a reducer was established using X-ray diffraction analysis and atomic force microscopy. Lanthanide and alkali-earth nitrates were shown to form highly dispersed powders of metal carbonates with an average particle size of ～23 nm under similar conditions.     

Phase formation in the ZrO(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>-CsF-H<Subscript>2</Subscript>O system at low concentration of the phosphorus-containing component

The ZrO(NO₃)₂-H₃PO₄-CsF-H₂O system was studied at 20°C along the section at a molar ratio of PO₄³⁻/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO₂ concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated for the first time: crystalline fluorophosphates CsZrF₂PO₄ · H₂O, amorphous oxofluorophosphate Cs₂Zr₃O₂F₄(PO₄)₂ · 3H₂O, and amorphous oxofluorophosphate nitrate CsZr₃O_1.25F₄(PO₄)₂(NO₃)_0.5 · 4.5H₂O. The compound Cs₃Zr₃O_1.5F₆(PO₄)₂ · 3H₂O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following new compounds was established: Cs₂Zr₃O_1.5F₅(PO₄)₂ · 2H₂O, Cs₂Zr₃F₂(PO₄)₄ · 4.5H₂O, and Zr₃O₄(PO₄)_1.33 · 6H₂O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical, thermal, and IR spectroscopic analyses.