ABO3型钙钛矿结构的可见光光催化剂LaCo0.5Ti0.5O3的设计与合成

采用溶胶-凝胶法在较低温度条件下设计合成了新型的具有ABO3型钙钛矿结构的三元金属复合氧化物LaCo0.5Ti0.5O3. 通过TG-DTA, XRD, XPS, UV-Vis DRS等测试技术和可见光光催化活性测试对其进行了表征. 结果表明, 与LaCoO3和La2Ti2O7相比, LaCo0.5Ti0.5O3样品表现出相对较高的可见光光催化活性, 并且合成温度较低. 这是由于原料中的Co2+和Ti4+离子通过电荷补偿作用使产物B位的两种金属均以+3价氧化态分布所致.     

Ti3C2Tx/Au@Pt纳米花复合膜的制备及其无酶H2O2传感器的应用

基于二维过渡金属碳化物(MXene)-Ti_3C_2T_x材料的导电性与Au@Pt纳米花的催化活性,组装了一种用于超灵敏和快速检测H_2O_2含量的Ti_3C_2T_x/Au@Pt纳米花无酶传感器。通过发射扫描电镜和X-射线衍射对制备的Ti_3C_2T_x进行表征。结果表明Ti_3C_2T_x材料表现出特有的手风琴结构,Ti_3C_2T_x/Au@Pt为以Au粒子为中心,Pt粒子环绕周围组成蒲公英状纳米球。研究了H_2O_2在Ti_3C_2T_x/Au@Pt纳米花修饰玻碳电极上的循环伏安曲线和时间电流曲线,结果显示该修饰电极检测H_2O_2具有线性范围良好(0.03～1 100μmol/L)、灵敏度高(检出限可达0.02μmol/L)、抗干扰性和再现性好等优点。与传统滴定法相比,该新型无酶传感器能在复杂环境下快速准确检出H_2O_2含量。     

Study of heterogeneities in steels and determination of soluble and total aluminium and titanium concentration by laser ablation inductively coupled plasma mass spectrometry

A methodology for bulk analysis of Al and Ti and for determination of soluble and total Al and Ti concentration in steel samples by laser ablation inductively coupled plasma mass spectrometry was developed. The spatial distribution (both at surface and within the sample) of the insoluble fraction of Al and Ti was also qualitatively estimated. Certified reference materials (CRMs) SS-451 to 460 (carbon steel) and 064-1 (Nb/Ti interstitial free steel), from BAS, and JK 2D (carbon steel) and JK 37 (highly alloyed steel), from SIMR, were studied. It was demonstrated that the insoluble fraction of Al and Ti is heterogeneously distributed. A series of nine glass samples (fused beads) with fixed Fe content and different Al and Ti contents was prepared by melting appropriate amounts of Fe₂O₃, Al₂O₃ and TiO₂ with a lithium tetraborate–sodium carbonate mixture. Quantitative determinations were performed by using calibration graphs obtained from the synthetic fused beads, with ⁵⁷Fe as internal standard; line scan laser sampling mode was used, focusing the laser beam at the sample surface. The optimized laser operating parameters were: laser pulse energy of 1.5 mJ, pulse repetition rate of 5 Hz, scanning speed of 5 μm s⁻¹ and preablation time of 20 s. The concentrations obtained for bulk analysis of CRM samples corresponded with the certified values within the experimental uncertainty. An acceptable concordance between certified and found values was attained for the determination of soluble and total Al and Ti in CRM 064-1 sample.     

电感耦合等离子体–原子发射光谱法同时测定铝合金中9种元素

建立电感耦合等离子体原子发射光谱同时测定铝合金中9种元素含量的方法。铝合金样品采用碱溶法预处理,以质量分数为40%的氢氧化钠溶液溶解,再用盐酸-硝酸混合酸酸化,然后用电感耦合等离子体原子发射光谱法同时测定样品中铁、硅、铜、镁、锰、锌、钛、镍、铬9种元素的含量。各元素的含量与对应的发射强度呈良好的线性关系,相关系数不小于0.9990;各元素检出限为0.0001%~0.0012%。应用该方法测定2个铝合金标准样品,测定结果与标示值一致,相对标准偏差为0.46%~2.14%(n=8)。将该法应用于试样测定时,加标回收率为92%~106%。该方法精密度和准确度高,操作简便、快速,适用于实验室铝合金多元素含量的检测。     

Effects of Ti and Zr Substituted on the Electrochemical Characteristics of MgNi-Based Alloy Electrodes

Mg-based hydrogen storage alloys MgNi, Mg0.9Ti0.1Ni, and Mg0.9Ti0.06Zr0.04Ni were successfully prepared by means of mechanical alloying （MA）. The structure and the electrochemical characteristics of these Mg-based materials were studied. The X-ray diffraction （XRD） result shows that the main phases of the alloys exhibit amorphous structure. The scanning electron microscopy （SEM） photograph shows that the particle size of Ti and Zr substituted alloys was about 2-4 μm in diameter. The cycle lives of the alloys were prolonged by adding Ti and Zr. After 50 charge-discharge cycles, the discharge capacity of Mg0.9Ti0.06Zr0.04Ni was 91.74% higher than that of MgNi alloy and 37.96% higher than that of Mg0.9Ti0.1Ni alloy. The main reason for the electrode capacity decay is the formation of Mg（OH）2 （product of Mg corrosion） at the surface of alloy. The potentiodynamic polarization result indicates that Ti and Zr doping improves the anticorrosion in an alkaline solution. The electrochemical impedance spectroscopy （EIS） results suggest that proper amount of Ti and Zr doping improves the electrochemical catalytic activity significantly.     

二氯二茂钛(锆)/格氏试剂体系在有机合成中的应用

介绍近几年来二氯二茂钛 (锆 ) /格氏试剂体系在有机合成中的应用 ,特别是使用该体系发展的新反应及其机理的研究情况     

EXAFS and XANES Studies of Silica-Titania Sol-Gel Films

A series of SiO₂-TiO₂ sol-gel films with and without heat treatment were analyzed by EXAFS and XANES spectroscopies. Both techniques indicate that essentially all Ti⁴⁺ ions remain four-fold coordinated, with a Ti–O bond distance between 1.82–1.85 Å. In the glassy films produced by heat treatment at 900° C, a gradual phase separation may occur at the nanoscale, as the TiO₂ concentration of the films increases.     

A novel method for the preparation of Bi4Ti3O12 nanoparticles in w/o microemulsion

Nanometer-sized Bi₄Ti₃O₁₂ particles have been prepared by chemical reaction of bismuth nitrate pentahydrate, titanium sulfate and ammonia solution in a reverse microemulsion system consisting of water, OP (P-octyl polyethylene glycol phenylether, non-ionic surfactant), n-butanol (co-surfactant), and cyclohexane (oil). Precursor hydroxides precipitated in the droplets of water-in-oil (w/o) microemulsion were calcined at 800 °C for 4 h to form Bi₄Ti₃O₁₂ nanoparticles. The samples were investigated with X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectrophotometer (FT-IR) and ultraviolet visible spectrophotometer (UV–vis). It was found that the as-prepared Bi₄Ti₃O₁₂ nanoparticles had small particle sizes (35 nm), high crystallinity, narrow size distributions and strong light absorption properties not only in the ultraviolet light but also in the visible light region.     

Microstructure and composition of annealed Al/Ti-metallization layers

Al/Ti multilayers with columnar grains were deposited by electron-beam evaporation on piezoelectric LiNbO₃ substrates. After annealing in air and under vacuum conditions dissolution of the Ti interlayer was observed for all samples. The original Ti interlayer dissolved completely and globular Al₃Ti grains were formed within an Al matrix. All samples had an oxidized adhesive Ti bottom layer and a 10 nm thin Al layer below this adhesive Ti bottom layer, which remains intact after the applied heat treatment. This resistance against dissolution by interdiffusion could be caused by the oxidation. These changes in the microstructure and in the chemical composition were investigated by conventional and analytical TEM.     

ICP-AES法测定钼酸铵及多钼酸铵中14个杂质元素

提出了用浓硝酸沉淀并分离大量基体钼，ICP-AES同时测定钼酸铵中14个杂质元素的方法，考虑了钼基体、酸度、谱线干扰及背景影响等情况。在未引入其它任何试剂的情况下，用硝酸既除去了大量的钼基体，又调整了溶液的酸度，用标准加入法测定钼酸铵中的杂质元素，无需加入高纯基准试剂进行基体匹配，有效降低了分析成本，又消除了由于忽略基准物质中杂质元素的含量给分析测定带来的误差。回收率在85％～112％之间。