表面活性剂辅助水热合成氧化钛纳米针溶胶

TiO₂ nanoneedles sol with particle size of 10～15 nanometer was synthesized by hydrothermal method using peroxo titanic acid as the precursor, cetyltrimethyl ammonium bromide(CTAB) as the surfactant. The product was characterized by XRD, TEM, HRTEM and selected area electron diffraction(SAED). The results show that the as-prepared products have high crystallinity and grow along the c-axis, with homogeneous morphology and good monodispersity. In addition, TiO₂ hydrosol possessed good photocatalytic activity for the photocatalytic degradation of methyl orange aqueous solution under the sunlight illumination.     

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.     

N 掺杂TiO2光催化剂的制备及其可见光活性研究

A visible-light-active photocatalyst was prepared by calcination of the hydrolysis product of tetrabutyl titanate with ammonia as precipitant. The photocatalyst was characterized by X-ray diffraction (XRD), UV-Vis diffuse reflection spectra (DRS), thermal gravimetric-differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM). The color of the photocatalyst was yellow and could absorb light wavelength under 550 nm as measured by DRS. The catalyst calcined at higher temperature will give lower absorbance for visible light. Structures of the sample were characterized mainly to be anatase by XRD except for the sample calcined at 700 ℃ which gave mixtures of anatase and rutile. TG-DTA results showed that temperature for anatase formation was 415 ℃. XPS results showed that doped-nitrogen was presented in the sample, they are important to show visible-light absorbency. The photocatalytic activities were evaluated using methyl orange and phenol as model pollutants, the results showed that over 90% of phenol could be degraded under visible light using N/TiO₂ as the catalyst after 4 hours reaction. Almost the same activity was found for the TiO₂ photocatalyst calcined at different temperature under sunlight but activities were different when the treatment was under UV light.     

微乳法制备纳米TiO2 /SiO2的结构及光催化研究

Nanosized TiO₂ and TiO₂/SiO₂ particles were prepared by hydrolysis of tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS) in the TX-100 reverse microemulsion. These particles were characterized by TG-DSC, XRD, FTIR, TEM，N₂ adsorption-desorption. Their photocatalytic activity was tested by degradation of methyl orange. The result shows that TiO₂/SiO₂ nanoparticles are with a monodispersed spherical phase and a uniform size distribution，and TiO₂ particles are dispersed on the surface of SiO₂. The band for Ti-O-Si vibration in FTIR was observed, the Ti-O-Si bond increased the stability of anatase TiO₂, suppressed the phase transformation of titania from anatase to rutile. And due to the addition of SiO₂, the average size of titania decreased from 38 nm in pure TiO₂ to 5 nm in TiO₂/SiO₂. It was found, under UV light irradiation, TiO₂/SiO₂ particles showed higher activity than pure TiO₂, and TiO₂/SiO₂(1/1) particles showed the highest photocatalytic activity on the photocatalytic decomposition of methyl orange, which was influenced by crystal structure, particle size, crystallinity and Surface area Characteristics.     

高分散纳米二氧化钛混合晶体的合成、结构与光催化性能

Using TiCl₄ and urea as the raw materials and nanometric carbon black as plate, nanometric mix-crystals of rutile and anatase TiO₂ were prepared at 100 ℃ for 10～180 min by homogeneous precipitation method. The effects of pH on the ratio of nanometer TiO₂ mix-crystals were also discussed. TEM measurement indicates that the TiO₂ is spherical particles, and the average diameter of the particles is 20 nm. XRD and TG-DTA were also used to characterize the nanometer mix-crystal materials. The photocatalytic experiment show that the mix-crystal material has the best photocatalytic reactivity. After being irradiated under the sunlight for 40 min, the compound can completely degrade the acid-red 3R.     

铁、氮共掺杂二氧化钛粉末的制备及光催化活性

Using TiCl₄ as the titanium source, nanoparticles of TiO₂ doped with nitrogen(N-TiO₂) were synthesized by triethylamine. TiO₂ powder codoped with iron and nitrogen(Fe/N-TiO₂) were prepared by adsorption-deposition of Fe³⁺ on N-TiO₂ and calcining at 400 ℃ for 2 h. From the XPS results for N1s binding energy at 399.6 eV and 396.6 eV, it is proposed that the partial N atoms as substitution atoms replace for O atoms in TiO₂ lattice. The onset of the absorption spectrum of Fe/N-TiO₂ has a 45 nm red-shift compared with that of TiO₂. The results of photocatalytic degradation of methylene blue solution indicate that Fe/N-TiO₂(0.45% Fe³⁺) has a higher activity. Its photocatalytic activity is about 2 times as high as that of pure TiO₂ under UV-light, and 3 times under sunlight. Doping of nitrogen in TiO₂ enhances photoresponse in visible light region and doping of Fe³⁺ reduces the recombination of electrons and holes. Both of the above effects are beneficial for improving the performances of Fe/N-TiO₂ photocatalyst.     

TiO2 / SiO2核 / 壳结构复合粒子的组装及其电化学性能

TiO₂ coated SiO₂ materials as anode for lithium-ion batteries were synthesized via an in situ hydrolysis of tetraethyl orthosilicate under ultrasonic irradiation using nanometer-sized TiO₂ colloids as precursors. The XRD patterns indicate that the as-prepared core/shell particles remain anatase after calcining below 800 ℃. TEM observation shows that the particle size of TiO₂ / SiO₂ composites is ca. 200 nm, and a homogeneous SiO₂ layer is coated on the surfaces of TiO₂ particles. FTIR spectra demonstrate that SiO₂ could have been coated on the surfaces of TiO₂ particles via a chemical bonding. In addition, the first specific charge and discharge capacities of the coated particle electrode were 66.4 mAh·g^-1 and 90.7 mAh·g^-1, respectively, which indicates that the TiO₂ / SiO₂ particles are more stable than the monodispersed TiO₂. Meanwhile, the new material has good lithium intercalation-deintercalation performances.     

Fe/La2O3纳米催化剂制备碳纳米管

Nanocrystalline LaFeO₃ was synthesised by the citrate method with La(NO₃)₃·6H₂O,Fe(NO₃)₃·9H₂O and citric acid as the raw materials. Before and after reduction, its structure was characterized by means of X-ray diffraction and transmission electron microscopy(TEM). And after reduction of LaFeO₃ oxide, the rare earth oxide, La₂O₃, prevents Fe particles from agglomerating and promotes the dispersion of nano-scale Fe particles (ca.40nm), which is one of the key factors for the growth of carbon nanotube. The carbon nanotubes from the catalytic de-composition of C₂H₂ were obtained using Fe/La₂O₃ nano-scale catalyst, which was formed from LaFeO₃ oxide as the catalyst precursor. The morphological structures of the carbon nanotube obtained have been examined by TEM. The results indicate that they are multi-walled nanotubes of good quality with inter diameter ranging from 20～25nm and length ranging from 25～40μm. The yields of carbon nanotube are 1.25g·gcat^-1 at the reaction temperature of 973K for 30min.     

A partially projected wave function for radicals

A partially projected wave function for odd electron systems with quantum number M=1/2, containing μu spin functions α and μ spin functions α, with fractional spin component αS_z=1/2 and 3/2 are derived from the totally projected wave function. To obtain these wave functions new symmetry relations between Sanibel coefficients for the odd electron case have been found, as well as the relations between primitive spin functions and their spin permutations. The wave function for the doublet state is shown not to contain contamination of the quadruplet state, and the wave function for the quadruplet does not have contamination of the duplet. Both wave functions exhibit equal forms except in the signs of their summation terms. The number of primitive spin functions depends on the number of electrons (n_s), it grows linearly as n_s=(N+3)/2. It can be considered as a generalization of the half projected Hartree–Fock wave function to the odd electron case. The HPHF wave function is defined for even electron systems and consists of only two Slater determinants, it has been shown to introduce some correlation effects and it has been successfully applied to calculate the low-lying excited states of molecules. Therefore, this investigation is the first step to propose a method to calculate the excited states of radicals when other methods are impracticable. This revised version was published online in July 2006 with corrections to the Cover Date.     

Highly Efficient Oxidative Coupling of Methane over LiCl-B2O3／MnO2 and Li2SO4-MnxOy／TiO2 Catalysts

Because of the ever-increasing consumption of crude oil. the role played by the natural gas as a raw material has become more and more important in chemical industry and the potential of methane used as a source for the production of ethylene has attracted much attention. In this paper, the LiCl-B2O3/MnO2 and Li2SO4-MnxOy/TiO2 catalysts for Oxidative Coupling of Methane (OCM) have been studied, and the results show that the catalysts exhibit high activity and selectivity, Furthermore. The influence of the components in the catalyst and the reaction conditions on OCM performance has been studied and a possible active new component, cubic Li4B7O12Cl. has been found.     

Crystal growth, structure determination, and optical properties of new potassium-rare-earth silicates K3RESi2O7 (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu)

Single crystals of K₃RESi₂O₇ (RE=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were grown from a potassium fluoride flux. Two different structure types were found for this series. Silicates containing the larger rare earths, RE=Gd, Tb, Dy, Ho, Er, Tm, Yb crystallize in a structure K₃RESi₂O₇ that contains the rare-earth cation in both a slightly distorted octahedral and an ideal trigonal prismatic coordination environment, while in K₃LuSi₂O₇, containing the smallest of the rare earths, lutetium is found solely in an octahedral coordination environment. The structure of K₃LuSi₂O₇ crystallizes in space group P6₃/mmc with a=5.71160(10) Å and c=13.8883(6) Å. The structures containing the remaining rare earths crystallize in the space group P6₃/mcm with the lattice parameters of a=9.9359(2) Å, c=14.4295(4) Å, (K₃GdSi₂O₇); a=9.88730(10) Å, c=14.3856(3) Å, (K₃TbSi₂O₇); a=9.8673(2) Å, c=14.3572(4) Å, (K₃DySi₂O₇); a=9.8408(3) Å, c=14.3206(6) Å, (K₃HoSi₂O₇); a=9.82120(10) Å, c=14.2986(2) Å, (K₃ErSi₂O₇); a=9.80200(10) Å, c=14.2863(4) Å, (K₃TmSi₂O₇); a=9.78190(10) Å, c=14.2401(3) Å, (K₃YbSi₂O₇). The optical properties of the silicates were investigated and K₃TbSi₂O₇ was found to fluoresce in the visible.     

Li_(1.3)Ti_(1.7)Al_(0.3)(PO_4)_3,Na_(1.3)Ti_(1.7)Al_(0.3)(PO_4)_3的离子交换研究

研究了在不同温度下的NaNO3和AgNO3水溶液中Li1.3Ti1.7Al0.3(PO4)3和Na1.3Ti1.7Al0.3(PO4)3离子交换行为.实验表明Li1.3Ti1.7Al0.3(PO4)3和Na1.3Ti1.7Al0.3(PO4)3均显示出了高选择性与Na+和Ag+进行离子交换的特征,且对Ag+的选择性高于Na+.升高温度可显著提高Ag/Li和Ag/Na的交换反应速度.     

The crystal chemistry of Bi6TP2O15+x, T=Fe, Ni, Zn: Isomorphism and polymorphism, structural relationship to Bi6TiP2O16

The crystal structures of compounds with nominal compositions Bi₆FeP₂O_15+x (I), Bi₆NiP₂O_15+x (II) and Bi₆ZnP₂O_15+x (III) were determined from single-crystal X-ray diffraction data. They are monoclinic, space group I2, Z=2. The lattice parameters for (I) are a=11.2644(7), b=5.4380(3), c=11.1440(5) Å, β=96.154(4)°; for (II) a=11.259(7), b=5.461(4), c=11.109(7) Å, β=96.65(1)°; for (III) a=19.7271(5), b=5.4376(2), c=16.9730(6) Å, β=131.932(1)°. Least squares refinements on F² converged for (I) to R1=0.0554, wR₂=0.1408; for (II) R₁=0.0647, wR₂=0.1697; for (III) R₁=0.0385, wR₂=0.1023. The crystals are complexly twinned by 2-fold rotation about , by inversion and by mirror reflection. The structures consist of edge-sharing articulations of OBi₄ tetrahedra forming layers in the a-c plane that then continue by edge-sharing parallel to the b-axis. The three-dimensional networks are bridged by Fe and Ni octahedra in (I) and (II) and by Zn trigonal bipyramids in (III) as well as by oxygen atoms of the PO₄ moieties. Bi also randomly occupies the octahedral sites. Oxygen vacancies exist in the structures of the three compounds due to required charge balances and they occur in the octahedral coordination polyhedron of the transition metal. In compound (III), no positional disorder in atomic sites is present. The Bi-O coordination polyhedra are trigonal prisms with one, two or three faces capped. Magnetic susceptibility data for compound (I) were obtained between 4.2 and 350 K. Between 4.2 and 250 K it is paramagnetic, μ_eff=6.1 μ_B; a magnetic transition occurs above 250 K.     

Near infrared study of aqueous rare-earth ethylsulfates

The near infrared spectra of aqueous solutions of the ethylsulfates of La, Nd, Gd, Tb, Er, Yb, Lu, Y, and Na have been determined from about 0.2 mol-dm^–3 to nearly saturation. The extinction coefficients of water have been calculated taking into account the absorption of ethylslfate anions determined in separate experiments. Their values appeared to be nearly the same as that of pure water. The relative contents of free OH groups in 0.5 and 0.7M solutions have been estimated from the absorbances at 1160 nm. They were lower in solutions of the heavy rare-earth ethylsulfates (Tb, Er, Yb, Lu) than in equimolar solutions of the lighter ones (La, Nd), confirming our previous view that secondary hydration of the heavy trivalent rare-earth cations is distinctly stronger than that of the lighter ones. A comparison of the spectra of these aqueous ethylsulfates with those of perchlorates shows that the structure-breaking ability of the C₂H₅SO ₄ ^– ion is much smaller than that of perchlorate anion.     

电感耦合等离子体光谱法(ICP-AES)测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量

针对银精矿样品复杂,难消解的特点,研究了不同酸溶法和碱熔法对样品的消解情况,建立了硝酸,盐酸,氢氟酸,高氯酸消解银精矿的方法。根据元素灵敏度和抗干扰性,选定各元素的测定波长。通过酸溶样和碱熔样测定结果比对,验证了方法准确性。建立了四酸消解-电感耦合等离子体光谱法测定银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的方法,元素的线性相关系数均在0.9999以上。通过共存元素干扰实验,确定了银精矿中高含量元素(铜、铅、锌、铁、锑、铋等)对测定元素结果没有影响。方法检出限：Cu 0.0063 mg/L, Pb 0.0159 mg/L ,Zn 0.0090 mg/L,As 0.0192 mg/L, Cd 0.0093 mg/L ,Ca 0.0084 mg/L, Mg 0.0075 mg/L, Mn 0.0081 mg/L。测定下限：Cu 0.0105mg/L,Pb 0.0265 mg/L, Zn 0.0150 mg/L, As 0.0320 mg/L, Cd 0.0155 mg/L, Ca 0.0140 mg/L, Mg 0.0125 mg/L,Mn 0.0135 mg/L。3个样品的相对标准偏差在0.87%~3.56%之间,加标回收率在95.00%~103.56%之间。方法流程短,操作简单,快速,灵敏度和再现性高,结果准确可靠,可以满足银精矿中铜、铅、锌、砷、镉、钙、镁、锰含量的测定。     

Structural studies of five layer Aurivillius oxides: A2Bi4Ti5O18 (A=Ca, Sr, Ba and Pb)

The room temperature structures of the five layer Aurivillius phases A₂Bi₄Ti₅O₁₈ (A=Ca, Sr, Ba and Pb) have been refined from powder neutron diffraction data using the Rietveld method. The structures consist of [Bi₂O₂]²⁺ layers interleaved with perovskite-like [A₂Bi₂Ti₅O₁₆]²⁻ blocks. The structures were refined in the orthorhombic space group B2eb (SG. No. 41), Z=4, and the unit cell parameters of the oxides are a=5.4251(2), b=5.4034(1), c=48.486(1); a=5.4650(2), b=5.4625(3), c=48.852(1); a=5.4988(3), b=5.4980(4), c=50.352(1); a=5.4701(2), b=5.4577(2), c=49.643(1) for A=Ca, Sr, Ba and Pb, respectively. The structural features of the compounds were found similar to n=2-4 layers bismuth oxides. The strain caused by mismatch of cell parameter requirements for the [Bi₂O₂]²⁺ layers and perovskite-like [A₂Bi₂Ti₅O₁₆]²⁻ blocks were relieved by tilting of the TiO₆ octahedra. Variable temperature synchrotron X-ray studies for Ca and Pb compounds showed that the orthorhombic structure persisted up to 675 and 475 K, respectively. Raman spectra of the compounds are also presented.     

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%。     

Preparation of ZrO2-TiO2-CeO2 and Its Application in the Selective Catalytic Reduction of NO with NH3

TiO₂,ZrO₂-TiO₂,andZrO₂-TiO₂-CeO₂ were prepared by co-precipitation method and characterized by X-ray diffraction (XRD), specific surface area measurements (BET), temperature programmed desorption (NH₃-TPD), oxygen storage capacity (OSC), and temperature programmed reduction (H₂-TPR). The results showed that ZrO₂-TiO₂-CeO₂ exhibited large number of surface strong acid, possessed some oxygen storage capacity, and strong redox property. The three materials were used as supports and the monolith catalysts were prepared with 1% (w) V₂O₅ and 9% (w)WO₃ for selective catalytic reduction (SCR) of NO with ammonia in the presence of excessive O₂, and the results of catalytic activity showed that the catalyst used ZrO₂-TiO₂-CeO₂ as support yielded nearly 100% NO conversion at 275 °C at a gas hourly space velocity (GHSV) of 10000 h⁻¹, and it had the best catalytic activity and showed great potential for practical application.     

The Phase Relations in the System In2O3–TiO2–MgO at 1100 and 1350°C

The phase relations in the system In₂O₃–TiO₂–MgO at 1100 and 1350°C are determined by a classical quenching method. In this system, there are four pseudobinary compounds, In₂TiO₅, MgTi₂O₅ (pseudobrookite type), MgTiO₃ (ilmenite type), and Mg₂TiO₄ (spinel type) at 1100°C. At 1350°C, in addition to these compounds there exist a spinel-type solid solution Mg_2−xIn_2xTi_1−xO₄ (0≤x≤1) and a compound In₆Ti₆MgO₂₂ with lattice constants a=5.9236(7) Å, b=3.3862(4) Å, c=6.3609(7) Å, β=108.15(1)°, and q=0.369, which is isostructural with the monoclinic In₃Ti₂FeO₁₀ in the system In₂O₃–TiO₂–MgO. The relation between the lattice constants of the spinel phase and the composition nearly satisfies Vegard's law. In₆Ti₆MgO₂₂ extends a solid solution range to In₂₀Ti₁₇Mg₃O₆₇ with lattice constants of a=5.9230(5) Å, b=3.3823(3) Å, c=6.3698(6) Å, β=108.10(5)°, and q=0.360. The distributions of constituent cations in the solid solutions are discussed in terms of their ionic radius and site preference effect.     

Microstructures of Some Bi-W-Nb-O Phases

Microstructures of three Bi-W-Nb-O phases have been examined by using high-resolution transmission electron microscopy. Bi₁₇W₂Nb₃O₃₉ and Bi₁₇WNb₃O₃₆ have incommensurate superstructures derived from the defect fluorite-type δ-Bi₂O₃ and can be regarded as intermediate phases between the type II solid solutions in the Bi-Nb-O and Bi-W-O systems. Bi₈W₂Nb₂O₂₃ has a Bi₂WO₆-like subunit cell with a stepped superstructure. Formation mechanisms of various superstructures are discussed.