单分散超细ZnO粉体的制备与表征

Monodispersed superfine ZnO powders with particle size of about 200～400nm were successfully prepared by the decompressed distillation process with n-butyl alcohol as the solvent. The starting materials were Zn(NO₃)2·6H₂O and NH₃·H₂O. TG-DSC， XRD， TEM and BET surface areas techniques were used to characterize the precursor and as-prepared superfine ZnO powders. In the preparation process of superfine ZnO powders， two techniques including the decompressed distillation with n-butyl alcohol and washing with absolute ethanol were used to avoid agglomeration. It is showed that the decompressed distillation process has a better effect in avoiding ag-glomeration than washing with absolute ethanol. The precursor obtained by the decompressed distillation technique has a lower calcination temperature than the one obtained by washing with absolute ethanol. Zincite phase of ZnO with some impurities was obtained when the precursor was calcined at 200℃ for 2h. After it was calcined at 300℃ for 2h， pure superfine ZnO powder was obtained.     

由镁、铝醇盐配合物合成纳米粒子MgAl2O4尖晶石

Mg and Al alkoxide complex was synthesized in a cell without battery separator by electrochemical dissolution of aluminum for 6 h and magnesium for 1.8 h at 45 ℃ in ethanol solution of 0.04 mol·dm^-3 (Bu₄N)Br with a current density of 100 mA·cm^-2. IR and Raman spectroscopy were used to characterize the structure of the precursor of MgAl₂O₄. The results show that the current efficiency attains 98.4% and the precursor is MgAl₂(OCH₂CH₃)₅(acac)₃. The acac^- group-containing precursor could prevent it from agglomeration. The xerogel was obtained by drying in vacuum for 24 h and hydrolysis under pH≈8.5 of the precursor, which was heated at 350 ℃ for 2 h to obtain the nano-MgAl₂O₄ powder. XRD and TEM were used to investigate the structure of nano-MgAl₂O₄. The result suggests that the xerogel with an average particle size of 10 nm and the Nano-sized Spinel MgAl₂O₄ Particle of 12 nm thus obtained are with high purity.     

不同原料对Li-Ni-Mn-O 5 V正极材料的结构和性能的影响

LiNi_0.5Mn_1.5O₄ was synthesized by solid-state reaction with different Ni containing precursors. The effect of precursor on electrochemical performance was studied. It was demonstrated that LiNi_0.5Mn_1.5O₄ synthesized with Ni(NO₃)₂·6H₂O as precursor had good charge-discharge performances. At the potential range of 3.0～5.0 V, the reversible capacity of the above LiNi_0.5Mn_1.5O₄ could reach to 145 mAh·g^-1 and remained 143 mAh·g^-1 after 10 cycles, while at 3.0～4.9 V, there was still 133 mAh·g^-1 reversible capacity, and was 125 mAh·g^-1 after 40 cycles. XRD results indicated that the synthesized compound was with spinel structure. The precursors and dispersion method had remarkable effect on the structures of the resulting compounds. Pure spinel phase could be obtained with mechanical ball-milled method and Ni(NO₃)₂·6H₂O as precursor, and trace amount of NiO phase could be detected in LiNi_0.5Mn_1.5O₄ with simple mixture method and using Ni(CH₃COO)₂·6H₂O, NiO and Ni₂O₃ as precurs-ors.     

铟锡氧化物纳米网的微波法制备及其光催化特性研究

By using ultrasonic and chemical liquid coprecipitation, the precursor was prepared with high purity In, SnCl₄·5H₂O and urea. The In₂O₃·SnO₂ nanonets were obtained from precursor by heating in microwave oven. The powders were characterized by XRD, TEM. The analyzed results show the sample is In₂O₃·SnO₂, and In₂O₃is rhombohedral system while SnO₂ is tetragonal system. The sample is in spherical grain shape, with average granularity of 35 nm, and the mesh diameter of 10～80 nm. The sample was with fluorescence and good photocatalytic performance for degradation of organic dyestuff.     

二水草酸亚铁热分解行为及脱水反应动力学研究

The thermal behavior of ferrous oxalate dihydrate (FeC₂O₄·2H₂O) was studied by thermogravimetry and differential thermal analysis (TGA and DTA). Three steps could be deduced for the decomposition from the TG,DTG and DTA curves obtained. One of the steps was the dehydration, the mass loss was 20.1%(the found value was in good agreement with the calculated value). Mathematical analysis with the integral and differential methods showed that the kinetics of dehydration of FeC₂O₄·2H₂O could be explained by F1 mechanism in nitrogen atmosphere. The kinetic equation of dehydration of FeC₂O₄·2H₂O could be expressed as: dα/dt=6.25×10¹⁹[exp(-170.27×10³/RT)](1-α)     

溶剂热-热解法制备具有纳米孔结构的Co3O4

Nanoporous rhombohedral Co₃O₄ was synthesized by thermal decomposition of the precursor obtained via a solvothermal method in the presence of Co(CH₃COO)₂·4H₂O, urea, sodium dodecyl sulfate (SDS), ethanol and water. The calcined sample was characterized by XRD, FTIR, SEM, TG-DTA, Nitrogen adsorption-desorption, cyclic voltammetry and galvanostatic charge/discharge measurements. The results show that the calcined sample at 400 ℃ is rhombohedral structure Co₃O₄ with nano-porosity assembled by uniform nanosheets. The BET surface area is 49 m²·g^-1 and its specific capacitance as single electrode is up to 233.4 F·g^-1 at 5 mA·cm^-2 current density.     

γ-Fe2O3纳米粉的低热固相制备及其电磁损耗特性(英)

The Fe(OH)₃ precursor was prepared by solid -state reaction with Fe(NO₃)₃·9H₂O, NaOH and dispersed poly-ethylene glycol at low heating temperature(25 ℃). Synthesis of iron oxide (γ-Fe₂O₃) nanoparticle was achieved by thermal decomposition of Fe(OH)₃·xH₂O precursor. The nanoparticle was characterized by TG-DTA, X-ray diffra-ction, TEM etc. The results showed that the nanoparticle was composed of γ-Fe₂O₃ and was a better absorber for electromagnetic wave within the low frequency band.     

草酸盐共沉淀法制备Y1.84La0.16O3纳米粉体

Nanopowder of Y_1.84La_0.16O₃ was prepared by oxalate co-precipitation method. The powder was characterized by TG-DTA, XRD and TEM. The results show that the precursor is Re₂(NO₃)₂(C₂O₄)₂·2H₂O (Re=Y, La), and the Y_1.84La_0.16O₃ nanopowders produced by calcining the precursor at 1 000 ℃ for 4 h are 20～40 nm spherical particles and well dispersed. The powders were with high sintering activity and could be fabricated to transparent ceramic without additive at 1 450～1 550 ℃ in H₂ atmosphere for 3 hours. The total transmission of the transparent ceramic could reach 80%.     

水合偏硼酸钾的热化学研究

Hydrated potassium monoborate(KBO₂·4/3H₂O) was obtained from an aqueous solution in a mole ratio of K₂O∶B₂O₃=2∶1 and characterized by powder X-ray diffraction(XRD)， infrared spectroscopy(FT-IR) and Raman spectroscopy. The enthalpy of solution of hydrated potassium monoborate， KBO₂·4/3H₂O， in approximately 1mol·dm^-3 aqueous hydrochloric acid was determined. Together with the previously determined enthalpies of so-lution of H₃BO₃ in approximately 1mol·dm^-3 HCl(aq) ，and of KCl in aqueous(hydrochloric acid+boric acid)， the standard molar enthalpy of formation of -(1411.11±0.84)kJ·mol^-1 for KBO₂·4/3H₂O was obtained from the standard molar enthalpies of formation of KCl(s)， H₃BO₃(s)， and H₂O(l). The standard molar entropy of formation of -422.94J·K^-1·mol^-1 and standard molar entropy of 163.47J·K^-1·mol^-1 for KBO₂·4/3H₂O were calculated from the thermodynamic relations. A group contribution method is applicable to KBO₂·4/3H₂O.     

氧钒(Ⅳ)碱式碳酸铵的热分析和纳米氧化钒的制备

The violet polycrystalline (NH₄)₅[(VO)₆(CO₃)₄(OH)₉]·10H₂O(NVCO) was simply synthesized by solution reaction using V₂O₅, HCl, N₂H₄·2HCl and NH₄HCO₃ as the starting materials. The results of TGA and DTA of NVCO under H₂(99.999%) atmosphere show that V₂O₃ forms at 620℃. The data of TG/DTG and DTA of NVCO under N₂(99.999%) atmosphere indicate that VO₂ forms at 367℃ and crystallizes at 390℃. In air atmosphere, the TG/DTG and DTA of NVCO show that V₂O₅ forms at 354℃, crystallizes at 366℃ and melts at 664℃. The three thermolysis processes of NVCO show that a large amount of H₂O, CO₂ and NH₃ gases fast releases during the thermolysis of NVCO, causing that the particles of the materials split and atomize strongly, thus to obtain V₂O₃, VO₂ and V₂O₅ nano-powders finally. According to the above of thermoanalytical results, V₂O₃, VO₂ and V₂O₅ powders were prepared respectively under H₂, N₂ and oxygen in a tube furnace. Chemical analysis and XRD ex-periments of the powders identify that pure V₂O₃ is obtained at 800℃ for 0.5h under H₂ atmosphere; crystalline VO₂ is obtained at 480℃ for 0.5h in N₂; amorphous VO₂ is obtained at 350℃ for 20min under N₂ atmosphere, this has been first reported to prepare amorphous VO₂ powder so far; pure V₂O₅ is obtained at 400℃ for 10min under oxygen. From the micrographs of the powders, the particle size of the V₂O₃, the crystalline VO₂ or the V₂O₅ powders is 35nm, 24nm or < 40nm, respectively. Above-mentioned results prove that NVCO is a good precursor for preparation of pure V₂O₃, VO₂ and V₂O₅ nano-powders under mild conditions.