新型阴极材料Ba0.5Sr0.5Co0.8Fe0.2O3-σ制备与性能研究

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-σ(BSCF), a new cathode material for solid oxide fuel cell (SOFC), was synthesized by polyacrylicacid (PAA) method. The lattice structures of samples calcined at different temperatures were characte-rized by XRD. Shrinkage, porosity and pore size of the porous BSCF as a function of sintering temperature were investigated. It was found that the cubic perovskite structure could be formed after calcination at 800 ℃ for 2 h, but not well crystallized as seen from some unknown phases, and the pure cubic perovskite structure was formed after calcination at 1 150 ℃ for 2 h. The particle size of BSCF was less than 1～2 μm. The shrinkage of the porous BSCF increased with sintering temperature, but the opposite was true for the porosity. After sintering at 1 100 ℃ for 4 h, the porous BSCF was still in an appropriate structure, with porosity of 29% and electrical conductivity above 400 S·cm^-1.     

固溶体结构对Ca2-xSrxZn4Ti15O36∶Pr3+发光性质的影响

Ca_2-xSr_xZn₄Ti₁₅O₃₆∶Pr red long decay phosphor was synthesized by high temperature solid state reaction. Photoluminescence property and crystalline and unit cell parameters of the orthorhombic were investigated by fluorescence spectrophotometer and by powder X-ray diffraction, respectively. The emission intensity at 618 nm changes sharply when the concentration of Sr²⁺ (x) is less than 0.1 and the emission intensity reaches the maximum when x is equal to 0.007. There is an obviously broad excitation band at 270 nm when x is equal to 0.003 and it disappears gradually when x is over 0.01. The unit cell a parameter of Ca_2-xSr_xZn₄Ti₁₅O₃₆∶Pr decreases while c parameter increases with the increases of the concentration of the doped Sr²⁺. When x is over 0.1 the value of the unit cell parameters a and c become stable. TL peaks of Ca₂Zn₄Ti₁₅O₃₆∶Pr, Ca_1.993Sr_0.007Zn₄Ti₁₅O₃₆∶0.002Pr³⁺, 0.002Na⁺, are located at 62 ℃, 88 ℃, respectively, which indicates that there are deeper traps in Ca_1.993Sr_0.007Zn₄Ti₁₅O₃₆∶0.002Pr³⁺, 0.002Na⁺.     

纳米尖晶石LixMn2O4的制备与电化学性能表征

Nano-spinel Li_xMn₂O₄(0.6 ≤x≤ 1.0) was synthesized by two steps of coprecipitation and calcination. The influences of calcination temperature, time and Li/Mn ratio on the crystal structure and the particle size of Li_xMn₂O₄ were investigated. It was shown that the higher the calcination temperature, the more complete the crystal structure, and the larger the particle size. Moreover, the influence of calcination time on the crystal structure was insignificant when it was more than 3h at 700℃. With the increase of x in Li_xMn₂O₄ in the range of 0.6～1.0, the d111 and lattice parameter a increased first and then decreased. The electrochemical properties of nano-spinel LiMn₂O₄ using as cathode material of lithium-ion battery were studied. The low discharge capacity might be due to the irreversible capacity loss brought by the large surface area and lattice vacancies of the nano-spinel.     

BaxCe0.8Y0.2O3-α固体电解质的氧离子导电性

Ba_xCe_0.8Y_0.2O_3-α(x=1.03，1，0.98) solid electrolyte samples show a single phase of orthorhombic perovskite of BaCeO₃. The oxide-ion conduction and transport number were detected in the temperature of 600～1000℃ by electrochemical oxygen permeation (oxygen pumping)， and compared with the results from the oxygen concentration cell. The relation between the ingredient of Ba and oxide-ion conduction was also researched. It was found that these electrolytes exhibited the mixed oxide-ionic and electronic hole conduction under the experimental temperature and oxygen gas. The oxide-ion transport numbers are 0.1～0.6， which are close to the results of the oxygen con-centration cell. They increase as the decrease of Ba content in the samples.     

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.     

CuO/Sn0.8Ti0.2O2催化剂的表征及对NO+CO反应活性研究

Reducibility and characteristics of CuO/Sn_0.8Ti_0.2O₂ catalysts were examined by using a microreactor-GC NO+CO reaction system, BET, TG-DTA, FTIR, XRD and H2-TPR techniques. CuO/Sn_0.8Ti_0.2O₂ had high activity in NO+CO reaction, showing 93% NO conversion at 300 ℃ in air, and 100% NO conversion at 225 ℃ after H₂ pretreatment. The pore size distribution of Sn_0.8Ti_0.2O₂ was mainly as micro-pores and meso-pores (1~5 nm), and the specific surface area and total pore volume of Sn_0.8Ti_0.2O₂ were 69 m²·g^-1 and 0.15 cm³·g^-1, respectively. As shown by XRD analysis, there was no CuO crystal diffraction peak at 9%CuO loading, but two CuO crystal diffraction peaks at 2θ 35.5° and 38.7° were present at 12% CuO loading. FTIR detected the adsorption of NO and CO on the surface of reduced 12%CuO/Sn_0.8Ti_0.2O₂. The Cu²⁺ sites and support surface adsorbed NO, and the process of NO adsorption led to the formation of N₂O and NO₃^-. In contrast, the Cu⁺、Cu⁰ sites and support surface adsorbed CO, and when the mixed gases of NO and CO were adsorbed by support surface, no NO₃^- was formed. H₂-TPR showed four reduction peaks (α, β, γ and δ). The α, β and γ peaks were the reductions of CuO species, and the δ peak was the reduction of Sn_0.8Ti_0.2O₂.     

Cu-Ni/La2O3热解C2H2制备碳纳米管的研究

Nano-sized and well-dispersed Cu-Ni/La₂O₃ can be obtained by reduction of LaCu_0.2Ni_0.8O₃ with the structure of perovskite. Using Cu-Ni/La₂O₃ as catalyst and C₂H₂ as carbon source, carbon nanotubes with a high yield and narrow diameter distribution can be obtained in the reaction temperature range of 650～700℃. Outer diameter of carbon nanotubes rangs from 9nm to 14nm. TG, Raman and XPS analysis indicate that carbon nanotubes prepared by Cu-Ni/La₂O₃ are relatively higher in graphitic degree.     

掺镍型层状LixNiyMn1-yO2正极材料的合成与电性能研究

A kind of cathode material of layered Li_xNi_yMn_1-yO₂ characterized with the O2 type has been synthesized by a simple method. Its precursor Na_xNi_yMn_1-yO₂ has been prepared from manganese dioxide， nickel hydroxide and sodium carbonate at high temperature in air and quickly cooled in cold water， then it has been exchanged by the melted LiNO₃ at 300～400℃ in air. The effects of calcine-temperature for the precursors and its compositions (the content of Na and Ni) on the electrochemical properties of the material Li_xNi_yMn_1-yO₂ have been investingated by XRD and electrochemical tests. The results show that the sample Li_0.7Ni_0.3Mn_0.7O₂， has the best electrochemical properties which shows only one charge-discharge potential stage of 2.8～3.0V and has a high specific capacity over 180mAh·g^-1 cycled between 2.0～4.20V. A significant structure transformation to the spinal-type phase has not been found in the charge-discharge cycling and the discharge specific capacity around 165mAh·g^-1 has re-mained after the 20th cyclings for the material.     

(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.     

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.     

Sol-gel synthesis of K3InF6 and structural characterization of K2InC10O10H6F9, K3InC12O14H4F18 and K3InC12O12F18

K₃InF₆ is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K₂InC₁₀O₁₀H₆F₉, K₃InC₁₂O₁₄H₄F₁₈ and K₃InC₁₂O₁₂F₁₈. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. The two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K₃InF₆ by decomposition at high temperature. The crystal structure of K₃InC₁₂O₁₄H₄F₁₈ is characterized by complex anions [In(CF₃COO)₄(OH_x)₂]^(5−2x)− and isolated [CF₃COOH_2−x]^(x−1)− molecules with x=2 or 1, surrounded by K⁺ cations. The crystal structure of K₃InC₁₂O₁₂F₁₈ is only constituted by complex anions [In(CF₃COO)₆]³⁻ and K⁺ cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K₂InC₁₀O₁₀H₆F₉ and K₃InC₁₂O₁₂F₁₈ were also performed at room temperature on pulverized crystals.     

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…     

Non-centrosymmetric Ba3Ti3O6(BO3)2

The compound previously reported as Ba₂Ti₂B₂O₉ has been reformulated as Ba₃Ti₃B₂O₁₂, or Ba₃Ti₃O₆(BO₃)₂, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO₃:BaTiB₂O₆ (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F²)=0.039 for 504 unique reflections. Ba₃Ti₃O₆(BO₃)₂ is isostructural with K₃Ta₃O₆(BO₃)₂. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba₃Ti₃O₆(BO₃)₂ is equal to 95% of that of LiNbO₃.     

A new 2212-type stair like structure: Bi14Sr21Fe12O61, m=5 member of the generic [Bi2Sr3Fe2O9]m[Bi4Sr6Fe2O16] family

A new oxide, Bi₁₄Sr₂₁Fe₁₂O_61, with a layered structure derived from the 2212 modulated type structure Bi₂Sr₃Fe₂O₉, was isolated. It crystallizes in the I2 space group, with the following parameters: a=16.58(3) Å, b=5.496(1) Å, c=35.27(2) Å and β=90.62°. The single crystal X-ray structure determination, coupled with electron microscopy, shows that this ferrite is the m=5 member of the [Bi₂Sr₃Fe₂O₉]_m[Bi₄Sr₆Fe₂O₁₆] collapsed family. This new collapsed structure can be described as slices of 2212 structure of five bismuth polyhedra thick along , shifted with respect to each other and interconnected by means of [Bi₄Sr₆Fe₂O₁₆] slices. The latter are the place of numerous defects like iron or strontium for bismuth substitution; they can be correlated to intergrowth defects with other members of the family.     

Ion-beam irradiation of lanthanum compounds in the systems La2O3-Al2O3 and La2O3-TiO2

Thin crystals of La₂O₃, LaAlO₃, La_2/3TiO₃, La₂TiO₅, and La₂Ti₂O₇ have been irradiated in situ using 1 MeV Kr²⁺ ions at the Intermediate Voltage Electron Microscope-Tandem User Facility (IVEM-Tandem), Argonne National Laboratory (ANL). We observed that La₂O₃ remained crystalline to a fluence greater than 3.1×10¹⁶ ions cm⁻² at a temperature of 50 K. The four binary oxide compounds in the two systems were observed through the crystalline-amorphous transition as a function of ion fluence and temperature. Results from the ion irradiations give critical temperatures for amorphisation (T_c) of 647 K for LaAlO₃, 840 K for La₂Ti₂O₇, 865 K for La_2/3TiO₃, and 1027 K for La₂TiO₅. The T_c values observed in this study, together with previous data for Al₂O₃ and TiO₂, are discussed with reference to the melting points for the La₂O₃-Al₂O₃ and La₂O₃-TiO₂ systems and the different local environments within the four crystal structures. Results suggest that there is an observable inverse correlation between T_c and melting temperature (T_m) in the two systems. More complex relationships exist between T_c and crystal structure, with the stoichiometric perovskite LaAlO₃ being the most resistant to amorphisation.     

Synthesis, crystal structure, infrared and Raman spectra of Sr4Cu3(AsO4)2(AsO3OH)4·3H2O and Ba2Cu4(AsO4)2(AsO3OH)3

The two new compounds, Sr₄Cu₃(AsO₄)₂(AsO₃OH)₄·3H₂O (1) and Ba₂Cu₄(AsO₄)₂(AsO₃OH)₃(2), were synthesized under hydrothermal conditions. They represent previously unknown structure types and are the first compounds synthesized in the systems SrO/BaO-CuO-As₂O₅-H₂O. Their crystal structures were determined by single-crystal X-ray diffraction [space group C2/c, a=18.536(4) Å, b=5.179(1) Å, c=24.898(5) Å, β=93.67(3)°, V=2344.0(8) Å³, Z=4 for 1; space group P4₂/n, a=7.775(1) Å, c=13.698(3) Å, V=828.1(2) Å³, Z=2 for 2]. The crystal structure of 1 is related to a group of compounds formed by Cu²⁺-(XO₄)³⁻ layers (X=P⁵⁺, As⁵⁺) linked by M cations (M=alkali, alkaline earth, Pb²⁺, or Ag⁺) and partly by hydrogen bonds. In 1, worth mentioning is the very short hydrogen bond length, D···A=2.477(3) Å. It is one of the examples of extremely short hydrogen bonds, where the donor and acceptor are crystallographically different. Compound 2 represents a layered structure consisting of Cu₂O₈ centrosymmetric dimers crosslinked by As1φ₄ tetrahedra, where φ is O or OH, which are interconnected by Ba, As2 and hydrogen bonds to form a three-dimensional network. The layers are formed by Cu₂O₈ centrosymmetric dimers of CuO₅ edge-sharing polyhedra, crosslinked by As1O₄ tetrahedra. Vibrational spectra (FTIR and Raman) of both compounds are described. The spectroscopic manifestation of the very short hydrogen bond in 1, and ABC-like spectra in 2 were discussed.     

Raman scattering investigations on lanthanum-doped Bi4Ti3O12-SrBi4Ti4O15 intergrowth ferroelectrics

The ferroelectric ceramics of Bi₄Ti₃O₁₂, SrBi₄Ti₄O₁₅, and lanthanum-doped Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅ were synthesized, and their Raman spectra were investigated. La-doping resulted in the enlargement of remnant polarization of Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅. The structure of the Bi₂O₂ layers and TiO₆ octahedra of the intergrowth was found to be different from those of Bi₄Ti₃O₁₂ and SrBi₄Ti₄O₁₅. La³⁺ ions exhibit pronounced selectivity for the occupation of A site as La content is lower than 0.50, and tend to be incorporated into Bi₂O₂ layers when the La content is higher than 0.50. Lanthanum substitution brings about the structural phase transition in Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅. The variation of ferroelectric property may be attributed to combined contribution from the decreasing of the oxygen vacancies, the relaxation of the lattice distortion, the destroying of the insulation and the space charge compensation effects of the Bi₂O₂ slabs.     

g-C_3N_4/CaTi_2O_5复合材料制备及其光催化性能

利用类石墨氮化碳(g-C_3N_4)和亚稳相钙钛氧化物(CaTi_2O_5)固相法制备C_3N_4/CaTi_2O_5复合材料。利用X射线衍射(XRD)、金相显微镜、扫描电子显微镜(SEM)及附带能谱分析仪(EDS)和N2吸附-脱附对样品的显微结构和比表面积进行检测分析,并用紫外-可见吸收光度计(UV-Vis)测试了样品的光吸收性能,研究C_3N_4与CaTi_2O_5物质的量之比(nC_3N_4/nCaTi_2O_5)对C_3N_4/CaTi_2O_5复合样品的物相结构和微观形貌的影响,同时考察C_3N_4/CaTi_2O_5复合样品在可见光照射下光催化降解罗丹明染料效果。实验结果表明:相比纯C_3N_4和CaTi_2O_5样品,C_3N_4/CaTi_2O_5复合样品在可见光下具有较高的光催化性能,随着nC_3N_4/nCaTi_2O_5增加,样品的光催化降解率随之增加而后降低,当nC_3N_4/nCaTi_2O_5=1∶1时,样品的光催化降解率达到最大值99.5%,并且循环重复利用5次后,样品的光催化剂降解率仍几乎保持不变。复合样品光催化性能提高主要归因于复合能级结构有效地抑制了电子和空穴复合所致。     

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.     

g-C3N4/CaTi2O5复合材料制备及其光催化性能

利用类石墨氮化碳（g-C₃N₄）和亚稳相钙钛氧化物（CaTi₂O₅）固相法制备C₃N₄/CaTi₂O₅复合材料。利用X射线衍射（XRD）、金相显微镜、扫描电子显微镜（SEM）及附带能谱分析仪（EDS）和N₂吸附-脱附对样品的显微结构和比表面积进行检测分析,并用紫外-可见吸收光度计（UV-Vis）测试了样品的光吸收性能,研究C₃N₄与CaTi₂O₅物质的量之比（n_C3N4/nCaTi₂O₅）对C₃N₄/CaTi₂O₅复合样品的物相结构和微观形貌的影响,同时考察C₃N₄/CaTi₂O₅复合样品在可见光照射下光催化降解罗丹明染料效果。实验结果表明：相比纯C₃N₄和CaTi₂O₅样品,C₃N₄/CaTi₂O₅复合样品在可见光下具有较高的光催化性能,随着n_C3N4/nCaTi₂O₅增加,样品的光催化降解率随之增加而后降低,当n_C3N4/nCaTi₂O₅=1：1时,样品的光催化降解率达到最大值99.5%,并且循环重复利用5次后,样品的光催化剂降解率仍几乎保持不变。复合样品光催化性能提高主要归因于复合能级结构有效地抑制了电子和空穴复合所致。