无氨湿法制备纳米晶In2O3及表征

Preparation of In₂O₃nano-scale powders by ultrasonic and homogeneous precipitation, using metal In and urea as raw materials, was reported for the first time, while the effects of reaction temperature, the ratio of the materials and the pH etc. on the preparation was dicussed. This method can be operated and industrialized easily with very low cost． The structural properties of precursor and In₂O₃were characterized by TG-DTA, XRD, ESCA and TEM. The results show that In₂O₃produced are very pure, monophase and spherical nano-scale powders with average size of 25 nm.     

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.     

球形Gd2O3∶Eu纳米发光材料的制备

Spherical nanometer Gd₂O₃∶Eu luminescent materials were prepared by homogeneous precipitation method, and the properties were studied also. TG, FTIR and XRD analysis showed that the precursor was carbonate, the cubic Gd₂O₃was obtained after calcination. TEM photographs indicated that the samples were spherical and well dispersed with nanometer and submicrometer size of 200～300 nm which is the nanoparticles’ aggregate. The mechanics of agglomerating growth is also discussed. ED photograph showed that the particle was crystalline. The PL analysis exhibited that CTB band of nanometer Gd₂O₃∶Eu was of 17 nm red shift to bulk materials, and the emission peak was broadened due to the surface and interface effect of nanocrystals.     

In2O3八面体的碳还原法制备及其发光性能研究

In₂O₃ octahedrons were synthesized by carbothermal reduction using In₂O₃ nanoparticles as the source material. The as-synthesized products were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray(EDX), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction analysis(SAED) and Room-temperature photoluminescence(PL) spectroscopy. The results show that the products are single-crystalline In₂O₃ octahedrons, the length of the octahedrons is in the range of 400～3 000 nm; the PL patterns display two peaks located at 447nm and 555 nm upon excitation at 380 nm, and the other two peaks located at 444 nm and 550 nm upon excitation at 325 nm; the excitation pattern shows two peaks located at 274 nm and 371 nm, respectively. The growth mechanism of the In₂O₃ octahedrons is discussed, and the high supersaturation ratio is considered as the key factor.     

电镀烧结法制备Ti/SnO2-Sb2O4电极的研究

The Ti/SnO₂-Sb₂O₄ electrode has been prepared by the electroplate-sinter method. The effect of SbCl₃ adding amount and sintering temperature on its electrode lifetime and oxygen evolution potential were investigated by means of EDX, SEM and XRD analysis. The results indicated that the electrode appeared the best performance when the SbCl₃ adding amounts was 0.2g and the sintering temperature was 550℃. In optimized conditions Ti substrate was entirely covered by SnO₂-Sb₂O₄ and the combinations among them were tight. Due to the use of electroplate method, the electrical conductivity, the oxygen evolution potential and the electrode lifetime were increased, so the elec-tro-catalytic activity and the electrochemical stability of the prepared electrode were found to be superior.     

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%.     

预氧化固气法合成LiNiO2的研究

LiNiO₂ was prepared by reaction of stoichiometric amounts of thoroughly-mixed LiOH·H₂O and preoxidation nanometer-scale Ni₃O₂(OH)₄ powders in O₂ at the temperature of 700℃ for 6h. The products were tested by XRD， XPS， SEM and electrochemistry methods. It was shown that product was LiNiO₂ single-phase， and the valence of nickel was +3; the average size of it was 40nm; its initial charge specific capacity is 168mAh·g^-1 and the coulomb efficiency is 90%; the second charge specific capacity is 160mAh·g^-1 and the coulomb efficiency is 96%.     

梯度材料LiNi0.8Co0.2O2的合成与表征

The gradient composite LiNi_0.8Co_0.2O₂ was synthesized using spherical Ni(OH)₂ particle coated by a sol-gel containing cobalt and lithium. The precursor was examined by DSC-TG. The gradient composite was characterized by SEM, EDS, XPS, XRD and ICP-AES. The XPS, EDS and ICP-AES results show that content of cobalt in the surface is higher than in the center of the spherical particle of the gradient composite. The first discharge specific capacity of the gradient composite sintered at 700 ℃ is 187.3 mAh·g^-1.     

混合溶剂前体法制备纳米CuO粉体及其性能表征

Nano-CuO was prepared by heating nano-Cu₂(OH)₂CO₃ precursors in different calcination temperatures. The precursor was synthesized from water-alcohol mixed solution of Cu(Ac)₂ using mixed solution of NaOH and Na₂CO₃as precipitants. XRD, FT-IR, TEM, TG-DTA and surface area measurement techniques were used to investigate the properties of the CuO powder. The results show that the spherical, well dispersed nano-CuO powder with the average size of 15 nm and higher catalytic activity for H₂O₂ decomposition was obtained at 300 ℃. With the increasing of calcination temperature, crystal of CuO grows up, agglomeration of the powder becomes heavier and catalytic activity decreases. FT-IR patterns revealed that the vibration fine structure of Cu-O bond in nano-CuO powder disappears and main absorption is red-shifted with the average size of nano-CuO reducing.     

超细掺锑SnO2制备工艺中前驱体洗涤分离的研究

Sb-doped SnO₂ ultrafine powders were prepared via oxidation-coprecipitation. Also the relation between surface characteristic (i.e. charged status and solvation) and precursor separation was studied. The results showed that the filter washing speed of precursor can be improved by reduced Precursor |ζ| values or lessen Precursor solvation. For example, adding to little organic solvents (such as ethanol )in Washing liquid morely accelerates to separation speed of precursor. This method and principle of washing and separation precursor can be used by other nona powders preparation with precipitation method, also sb doped SnO₂ ultrafine powders will be prepared easily in industry with it.     

(ZrO2)1-x(Yb2O3)x纳米晶的水热法合成及其烧结体的电性能

(ZrO₂)_1-x(Yb₂O₃)_x (x=0.07, 0.09, 0.11) nanocrystallites were hydrothermally prepared in basic media by using co-precipitated Zr(OH)₄ and Yb(OH)₃ as precursor. The nanocrystallites have small particle sizes of 5.8~7.5 nm, narrow size distribution, less agglomeration and high sinterability. The oxide-ionic conduction properties of the prepared ceramics were investigated by means of AC impedance spectroscope, oxygen concentration cell at 600~1 000 ℃. The results show that the ceramic with x=0.09 is superior to the ceramics with x=0.07 and 0.11 in oxide-ionic conduction.     

共沉淀法制备负热膨胀性ZrW2O8粉体及其粒径控制初探

Negative thermal expansion (NTE) material ZrW₂O₈ powders were synthesized using co-precipitation route. The precursor of ZrW₂O₈ was studied by Thermogravimetric and differential scanning calorimetry (TG-DSC). The structure and morphology of the resulting powders were characterized by Powder X-ray diffraction (XRD) and Scanning electron microscopy (SEM), respectively. The results showed that the samples were single phase of α-ZrW₂O₈ with regular shape. High temperature X-ray diffraction measurement indicated that the thermal expansion coefficient of ZrW₂O₈ was -10.35 × 10^-6 K^-1 in the temperature range from room temperature to 150 ℃, -3.08 ×10^-6 K^-1 from 200 ℃ to 600 ℃ and the average value was -5.38 × 10^-6 K^-1. At the same time, polyethylene glycol (PEG) was used as dispersant to primary control the size of ZrW₂O₈.     

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.     

LiMn2O4的湿法合成及锰的光度法测定研究

The LiMn₂O₄ spinel was prepared by wet method using Li₂CO₃， Mn(CH₃COO)₂·4H₂O and CO₂ as raw ma-terials. The products were measured by TG/DTA， XRD， IR. The results Showed that the sample calcined at 800℃ for 10h was well crystallized monophase product. The contents of Mn(Ⅲ) and Mn(Ⅳ) of LiMn₂O₄ spinel were determined simultaneously by spectrophotometric analysis with pyrophosphoric acid.     

纳米晶SnO2粉体的合成

Crystalline tin oxide nanoparticles were synthesized by the direct precipitation from the starting material granulated tin. TG-DTA of the precursor showed a heavy weight loss at about 130℃ accompanied by an endothermic peak， two exothermic peaks above 200℃ accompanied by small weight loss indicated the decomposition and the oxidation of residual NO₃^- ion and PEG. XRD showed that obtained particles agreed well with the determination result of bulk SnO₂. The broadened XRD patterns became sharper as the calcining temperature turned to higher， it was indicated that the growth of the particle was exhibited. The surface area of the particles calcined at 300℃ was 161.1m²·g^-1 and declined as the calcining temperature turned to higher. TEM showed an heavier agglomeration at higher temperature.     

锂离子电池正极材料LiMn2O4的合成与晶体结构（英）

Spinel LiMn₂O₄ powders were prepared using two-step synthesis method consisting of solid-state reaction method and citrate modified sol-gel method. The effects of the calcination temperature and the Li/Mn ratio of raw materials were studied on the physicochemical and electrochemical properties of the spinel LiMn₂O₄ powders, such as crystallinity, lattice constant and density. The title compound was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Polycrystalline LiMn₂O₄ powers calcined at 750 ℃ were found to be composed of very uniformly-sized microcrystal with an average particle size of 300 nm. The improvement in electrochemical properties was mainly attributed to the process of re-grinding by absolute alcohol.     

纳米三氧化二钴低温热容和热力学性质的研究

The isobaric molar heat capacities of nano Co₂O₃ were determined by an adiabatic calorimeter in the temper-ature range from 78 to 350K. No phase transition takes place in this temperature range. The relationship of C_p，m with respect to thermodynamic temperature T was established as C_p，m=-11.998X³-9.6431X²+63.478X+81.291(J·K^-1·mol^-1) ， where X=(T-201.903)/121.535， the correlation coefficient R₂=0.9996. Ac-cording to this relationship and the relationships between thermodynamic functions， the thermodynamic functions of nano Co₂O₃ relative to the standard temperature of 298.15K were derived based on the measured heat capacity data. The average grain size of the studied nano Co₂O₃ sample was determined to be 12nm by TEM.     

MgFe2O4纳米粉体的水热合成及其表征(英)

MgFe₂O₄ nanoparticles were hydrothermally synthesized at 150 ℃ using iron nitrate [Fe(NO₃)₃·9H₂O], magnesium nitrate [Mg(NO₃)₂·6H₂O] and sodium hydroxide (NaOH) as starting materials by carefully controlling the reaction conditions. The influences of several factors such as presence or absence of Na⁺, molar ratio of Fe³⁺ / Mg²⁺, concentration of mental ions, temperature and reaction time on resultant products were investigated in the hydrothermal process. The sample was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and its magnetic properties were measured using vibrating sample magnetometer (VSM).     

锐钛矿型TiO2水溶胶的低温制备及其表征

Anatase titanium dioxide hydrosol was prepared at low temperature by a simple method. The title material was characterized by TEM, XRD, FTIR and BET, respectively. The photocatalytic activity of the as-prepared TiO₂ was evaluated by the degradation of methyl orange solution under sunlight and the photocatalytic oxidation of acetone in air. The results showed that the titanium dioxide hydrosol was composed of anatase phase with average grain size of about 7 nm, and the crystallinity became more perfect with the increase of temperature. The BET surface areas were more than 220 m²·g^-1 for these samples. It is found that the photocatalytic activity was much better for the higher heat processing temperature. Especially, the photocatalytic activity of the sample with a heat treatment of 110 ℃ was better than that of P25. In addition, TiO₂ hydrosol also possessed good photocatalytic activity under the sunlight illumination.     

硬脂酸法制备超细K2La2Ti3O10及其酸交换性质研究

A new stearic acid method(SAM) has been used to prepare ultrafine K₂La₂Ti₃O₁₀ nanocrystalline. Each state of synthesis process was followed by the use of FT-IR analysis. The resulting materials have been characterized by means of XRD， TEM， BET surface area analysis. The acid-exchanging property of the obtained product was also studied. The experimental results showed that comparing with the product of traditional solid-state reaction， the particle size of the K₂La₂Ti₃O₁₀ synthesized by SAM is greatly reduced， BET surface area is high(more than 11.83m²·g^-1) and has different acid-exchanging properties. It can be easily exfoliated in 2mol·L^-1 HNO₃ so-lution.