碳纳米管负载的Fe2O3催化剂制备

Carbon nanotubes were modified by FeSO₄-H₂O₂ system, iron hydroxides were adsorbed on the wall of carbon nanotubes simultaneously. These precursors were treated at 723K for 2 h under hydrogen, nitrogen and air atmosphere to prepare carbon nanotubes supported γ-Fe₂O₃catalyst, γ-Fe₂O₃and α-Fe₂O₃compound catalyst and amorphous Fe₂O₃catalyst, respectively. This is green method to prepare high Fe₂O₃loading (≥50 %) catalyst without adding other cation. The different structures Fe₂O₃catalysts can be synthesized by controlling the condition of thermal treatment to content active phase requirements for different catalytic reactions. The paper presents a new method to prepare carbon nanotubes supported catalysts.     

Ceramic Filter Balls Loaded with α-Fe2O3 and Their Application to NH3-N Wastewater Treatment

Hydrolysis reaction of Fe(NO₃)₃ at a high temperature in the presence of urea as the homogeneous precipitant was studied. With the prepared ceramic filter balls loaded with α-Fe₂O₃ after high temperature calcination, the loading of α-Fe₂O₃ on the porous ceramic filter balls from Fe(NO₃)₃ solutions of different concentrations and mechanical stability of the loaded α-Fe₂O₃ were studied. The product was characterized using XRD and SEM. Adsorption experiments were conducted to evaluate the performance of the product in adsorbing NH₃-N. It turned out that the specific surface area of the ceramic filter balls loaded with α-Fe₂O₃ had increased to 36.5387 m²/g from original 4.6127 m²/g. When the concentration of Fe(NO₃)₃ was 0.40 mol/L, the loading of α-Fe₂O₃ on the ceramic filter balls accounted for 8.4% of the total mass of the adsorbent and α-Fe₂O₃ was adsorbed on the filter balls very well. The adsorption isotherm of NH₃-N on the ceramic filter ball adsorbent loaded with α-Fe₂O₃ was of Langmuir type. The saturated adsorption capacity was 3.33 mg/L, and the adsorption constant K was 0.1873. NH₃-N was adsorbed by α-Fe₂O₃ more easily, which was a kind of specific adsorption.     

准球形α-Fe2O3的形成过程研究

The formation process of pseudo-spherical α-Fe₂O₃ particles obtained through the hydrolysis of 0.01 mol·L^-1 FeCl₃ solution was studied by means of TEM and XRD. The results show that the growth of α-Fe₂O₃ nuclies is through the diffusion mechanism. Although the presence of CTAB in the FeCl₃ solution has no effect on the growth process of pseudo-spheric α-Fe₂O₃ particles, more uniform particles are obtained, and the particles are self-assembled to form two-dimensional ordered structure due to the effect of CTAB. The optical character of these α-Fe₂O₃ particles was investigated, and the band-gap of which is about 2.49 eV.     

球形α-Fe2O3纳米粉体的超声水解法合成与表征

Hematite (α-Fe₂O₃) nanopowder was synthesized from 0.1 mol·L^-1 FeCl₃ solution by sonochemical hydrolysis method, and characterized by X-ray diffraction (XRD), transmission electron micrograph (TEM), Fourier transform infrared (FTIR), Fourier transform Raman (FT-Raman) and X-ray photoelectron spectroscopy (XPS). The results showed that the spherical, well-dispersed α-Fe₂O₃ nanopowder was obtained with the average size of 20 nm. The possible mechanism for the formation of α-Fe₂O₃ nanoparticals was also discussed.     

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.     

磁性Fe3O4 /壳聚糖的化学修饰及包覆机理研究

Nano-sized Fe₃O₄ powder was prepared through an Oxygenation-Hydrothermal method. The chitosan magnetic complex was prepared by coating chitosan on the surface of Fe₃O₄ powders through Microlatex-Crosslinking Method. The product was characterized by IR， XRD， TEM， Vibrating Sample Magnetometer (VSM)， TG methods. Results show that the as-prepared powder is 25 nm in size and shows supermagnetism. The content of magnetite in microspheres is 37.8%. The mechanism for the coating reaction of chitosan to Fe₃O₄ nanoparticles is also suggested.     

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.     

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.     

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%.     

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.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

B2O3-Bi2O3-ZnO-Al2O3玻璃助烧剂对BaTiO3陶瓷烧结条件、晶体结构和介电性能的影响

通过调节B₂O₃-Bi₂O₃-ZnO-Al₂O₃(BBZA)玻璃的添加量研究其对钛酸钡(BaTiO₃)陶瓷烧结条件、晶体结构和介电性能的影响。结果表明：添加适量的BBZA玻璃能够有效地将BaTiO₃陶瓷烧结温度由1 350℃降至950℃,并使其致密化。同时,添加BBZA玻璃后,BaTiO₃的晶体结构随着烧结温度的升高而发生转变(立方相→四方相)。另外,BBZA玻璃的引入使BaTiO₃陶瓷的居里峰得到了有效的抑制和拓宽。陶瓷微观形貌显示,玻璃相均匀分布在BaTiO₃晶粒表面。优化的BaTiO₃陶瓷制备条件如下：BBZA添加量(质量分数)为2.0%,烧结温度为950℃。在该条件下制备的BaTiO₃陶瓷介电常数达到1 364,介电损耗低至1.2%。     

MgAl2O4尖晶石对锂离子电池正极材料LiMn2O4的循环性能影响研究

MgAl₂O₄ spinel doping into cathode materials LiMn₂O₄ was used to improve the cyclic performance of the cathode. X-ray analysis results showed, when MgAl₂O₄ precursors were mixed with LiMn₂O₄ and sintered at 770 ℃ for 12 hour, MgAl₂O₄-LiMn₂O₄ mulriple spinel with the same physical characteristics as pure LiMn₂O₄ were synthesized. The electro-chemical performance testing showed, comparing with pure LiMn₂O₄, the first charge-discharge capacity of doping materials somewhat reduced, but the cyclic performance improved. The mechanism for doping material was also discussed.     

B2O3-Bi2O3-ZnO-Al2O3玻璃助烧剂对BaTiO3陶瓷烧结条件、晶体结构和介电性能的影响

通过调节B₂O₃‐Bi₂O₃‐ZnO‐Al₂O₃(BBZA)玻璃的添加量研究其对钛酸钡(BaTiO₃)陶瓷烧结条件、晶体结构和介电性能的影响。结果表明：添加适量的BBZA玻璃能够有效地将BaTiO₃陶瓷烧结温度由1350℃降至950℃,并使其致密化。同时,添加BBZA玻璃后,BaTiO₃的晶体结构随着烧结温度的升高而发生转变(立方相→四方相)。另外,BBZA玻璃的引入使BaTiO₃陶瓷的居里峰得到了有效的抑制和拓宽。陶瓷微观形貌显示,玻璃相均匀分布在BaTiO₃晶粒表面。优化的BaTiO₃陶瓷制备条件如下：BBZA添加量(质量分数)为2.0%,烧结温度为950℃。在该条件下制备的BaTiO₃陶瓷介电常数达到1364,介电损耗低至1.2%。     

BaO-Al2O3-B2O3系密封玻璃的结构与性质

The BaO-Al₂O₃-B₂O₃ glasses manufactured for solid oxide fuel cell(SOFC) sealing were studied. The effect of different n_BaO/n_B2O3 on crystal, thermal properties, density and infrared spectra of this system has been discussed. The results show that the trends of crystallization, glass transformation temperature, dilatometric softening temperature and density increase with n_BaO/n_B2O3 values. But a typical property deviation occurs when n_BaO/n_B2O3 is 0.875, and its coefficient of thermal expansion has the maximum at this point. The changes of properties can attribute to the conversion of boron from tetrahedral coordination to trigonal, breakage of the local glass network and interaction between the network modifiers. These can be proved by infrared spectra of glasses. Thermal properties of some studied samples are suitable for the sealing of SOFC using Sm doped ceria electrolyte and operating at 400～600 ℃.     

The crystal structure determinations and refinements of K2S2O7, KNaS2O7 and Na2S2O7 from X-ray powder and single crystal diffraction data

The crystal structures of K₂S₂O₇, KNaS₂O₇ and Na₂S₂O₇ have been solved and/or refined from X-ray synchrotron powder diffraction data and conventional single-crystal data. K₂S₂O₇: From powder diffraction data, monoclinic C2/c, Z=4, a=12.3653(2), b=7.3122(1), , β=93.0792(7)°, R_Bragg=0.096. KNaS₂O₇: From powder diffraction data; triclinic , Z=2, a=5.90476(9), b=7.2008(1), , α=101.7074(9), β=90.6960(7), γ=94.2403(9)°, R_Bragg=0.075. Na₂S₂O₇: From single-crystal data; triclinic , Z=2, a=6.7702(9), b=6.7975(10), , α=116.779(2), β=96.089(3), γ=84.000(3)°, R_F=0.033. The disulphate anions are essentially eclipsed. All three structures can be described as dichromate-like, where the alkali cations coordinate oxygens of the isolated disulphate groups in three-dimensional networks. The K-O and Na-O coordinations were determined from electron density topology and coordination geometry. The three structures have a cation-disulphate chain in common. In K₂S₂O₇ and Na₂S₂O₇ the neighbouring chains are antiparallel, while in KNaS₂O₇ the chains are parallel. The differences between the K₂S₂O₇ and Na₂S₂O₇ structures, with double-, respectively single-sided chain connections and straight, respectively, corrugated structural layers can be understood in terms of the differences in size and coordinating ability of the cations.     

Magnetic diphase nanostructure of ZnFe2O4/γ-Fe2O3

Magnetic diphase nanostructures of ZnFe₂O₄/γ-Fe₂O₃ were synthesized by a solvothermal method. The formation reactions were optimized by tuning the initial molar ratios of Fe/Zn. All samples were characterized by X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and Raman spectra. It is found that when the initial molar ratio of Fe/Zn is larger than 2, a diphase magnetic nanostructure of ZnFe₂O₄/γ-Fe₂O₃ was formed, in which the presence of ZnFe₂O₄ enhanced the thermal stability of γ-Fe₂O₃. Further increasing the initial molar ratio of Fe/Zn larger than 6 destabilized the diphase nanostructure and yielded traces of secondary phase α-Fe₂O₃. The grain surfaces of diphase nanostructure exhibited a spin-glass-like structure. At room temperature, all diphase nanostructures are superparamagnetic with saturation magnetization being increased with γ-Fe₂O₃ content.     

The Al2O3-Fe2O3 Mixed Oxidic System, I. Preparation and Characterization

A series of Al₂O₃-Fe₂O₃ mixed oxidic solids with composition ranging from 0 to 100% of Fe₂O₃ were prepared and examined for structural characteristics. XRD diagrams showed the presence of α-Al₂O₃ and hematite phases. The analysis of M?ssbauer spectra revealed the existence of two iron containing phases. The specific surface area of the mixture decreases by the addition of iron and depends on the crystal phases of the mixture. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Ternary System Li2O-Al2O3-B2O3: Compounds and Phase Relations

The ternary system Li₂O-Al₂O₃-B₂O₃ is reinvestigated with solid-state reaction and X-ray powder diffraction technique to clarify some long-standing uncertainties. The phase relations are constructed based on the phase identifications of 51 ternary samples. Six ternary compounds, Li₂AlB₅O₁₀, LiAlB₂O₅, Li₃AlB₂O₆, Li₂AlBO₄, LiAl₇B₄O₁₇ and a compound with a composition close to 0.66Li₂O·0.06Al₂O₃·0.28B₂O₃, are observed or confirmed in this system, and the thermal stability of these ternary compounds is also discussed on the basis of DTA experimental results.     

The Al2O3-Fe2O3 Mixed Oxidic System, II. Catalytic Decomposition of N2O

N₂O decomposition was examined over a series of Al₂O₃-Fe₂O₃ mixed oxidic solids with composition ranging from 0 to 100% of Fe₂O₃. The catalytic activity of the solids runs parallel to the number of atoms of iron in the Al_2−x Fe_xO₃ solid solution phase. Two compensation effects are present. The first corresponds to catalysts rich in alumina, and the second one to catalysts rich in hematite. This revised version was published online in June 2006 with corrections to the Cover Date.