纳米结构钛酸盐电极快速测定水体COD

分析了纳米结构钛酸盐电极快速测定COD的基本原理及COD标准物质定值方法。通过对纳米结构钛酸盐表征分析,钠型钛酸盐电极具有较高的灵敏度,外加0.7 V工作电位,测定COD溶液标准物质的线性相关系数大于0.995,误差在±8%以内;与国标方法比较,测量同一水样的误差在±15%以内。纳米结构钛酸盐电极可用于测量水体COD。     

Impact of titanate coupling agent on properties of high density polyethylene composite filled with coal gangue

In this study, surface modification of coal gangue (CG) was performed with titanate coupling agent 201 (isopropyl tri(dioctylpyrophosphate) titanate), and the effects of surface modifier on mechanical properties and thermal stability of high-density polyethylene filled with CG (HDPE/CG) and high-density polyethylene filled with modified CG (HDPE/mCG) composites were investigated. The coupling agent was successfully grafted on CG surface through chemical reaction according to the analyses of Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the coupling agent can effectively enhance the hydrophobicity of surface that was verified by water contact angle beyond 90° of modified CG sample. With the introduction of coupling agent, some enhancements of tensile strength, flexural strength, and impact strength were observed in HDPE/mCG compared with HDPE/CG, due to the improved compatibility between mCG fillers and matrix. The increased storage modulus and decreased loss factor of HDPE/mCG composite further confirm the stronger interface adhesion after modification. Moreover, it is found that titanate coupling agent 201 can improve the thermal stability of HDPE/mCG composite to some extent.     

钛酸锶光催化剂的改性研究进展

钛酸锶（SrTiO3）光催化剂是一种钙钛矿型三元氧化物,具有较强的氧化还原能力、良好的物理化学稳定性及环境友好等特点,在光催化各领域得到了广泛应用,如制氢/降解/光电催化等。SrTiO3对太阳光的利用率较低,且其本征光催化活性受光生载流子分离效率等因素限制,阻碍了实际应用。针对以上问题,将围绕国内外SrTiO3改性研究的现状进行综述,主要从掺杂、负载、复合改性等方面进行陈述。最后,对高效稳定SrTiO3光催化剂的未来发展趋势进行展望。     

Dielectric behaviour of La substituted BPZT ceramics

Here, we report dielectric behaviour of lanthanum substituted Ba_0.80Pb_0.20Ti_0.90Zr_0.10O₃ (BPZT) ceramics. The material series with compositional formula Ba_0.80−xLa_xPb_0.20Ti_0.90Zr_0.10O₃ (BLPZT) with x varying from 0 to 0.01 in the steps of 0.0025 was chosen for investigations. The material was synthesized by solid state reaction method. Reacted powder compacted in form of circular discs were sintered at 1325 °C. All the samples were subjected to X-ray diffraction (XRD) analysis and found to be single phase. Dielectric behaviour was studied as a function of frequency and temperature and Curie temperature (T_c) was determined. T_c was found to decrease with increasing x. The details are discussed and presented in this paper.     

Synthesis and microstructure of Ca-doped BaTiO3 ceramics prepared by high-energy ball-milling

The calcium-substituted barium titanate ceramics were prepared by solid state reaction technique. High-energy ball-milling was used for processing the powder. The microstructure of Ba_1−xCa_xTiO₃ ceramics was investigated by SEM techniques. The microstructure of Ba_1−xCa_xTiO₃ ceramics shows dense and uniform micrograph in all samples and the grain size is large. In this study the quantitative analysis of the ceramographs is shown and the variation of the different parameters with various doping concentration is discussed. Compositional analysis is ascribed to the occupancy of some Ca²⁺ to the Ti⁴⁺ sites.     

<Emphasis Type="Italic">In Situ</Emphasis> Synthesis of Field-responsive Nanocrystalline BaTiO<Subscript>3</Subscript> Particles Modified with Functional Organics

Nanocrystalline BaTiO₃ particles modified with polarizable ligands were synthesized through hydrolysis of modified metal–organics below 100°C. BaTiO₃ precursor was synthesized from barium metal, titanium isopropoxide and polarizable ligands in a mixture of ethanol and 2-ethoxyethanol. The modified Ba–Ti complex alkoxide was hydrolyzed yielding BaTiO₃ particles modified with organics. The crystallinty of nanometer-sized particles was dependent upon the hydrolysis conditions, and increased with increasing water amount and time. The nanocrystalline particles were identified to be BaTiO₃ by X-ray diffraction (XRD) and electron diffraction. A fluid consisting of modified BaTiO₃ particles and silicone oil revealed a typical electrorheological (ER) behavior on applying DC field. The ER behavior was found to depend upon the kind of ligand. 4-Fluorobenzyloxy modifier revealed the highest yield stress in the ER measurement among 4-substitued benzyloxy ligands examined.     

Coplanar Phase Shifters Based on Ferroelectric Thin Films

Barium strontium titanate (Ba_0.6Sr_0.4TiO₃, short for BST) thin films were prepared by RF-magnetron sputtering. The dielectric tunability, loss tangent, remanent polarization (2Pr) and coercive electric field (Ec) of the BST films are respectively 29.5%, 0.013, 2.29 μC/cm² and 22.27 kV/cm at 1 kHz and 20 V. The designed coplanar waveguide (CPW) phase shifter consists of 56 same sections. It is shown that the fabricated lines of electrodes are smooth and the widths at the tip of bottom electrodes are about 5 μm. At the central frequency of 28 GHz and a bias voltage of 20 V, the figure of merit is approximately 13°/dB.     

Preparation and characterization of titania based nanowires

A new method for preparation of titania nanowires with diameter around 10 nm and length up to 2–3 μm is described. The precursor was prepared from sodium titanate by adding ethylene glycole (EG) and heating at temperature of 198°C for 6 h under reflux. The sodium titanate glycolate formed by this way aggregated into 1D nanostructures and was subsequently transformed into titania glycolate during a chemical treatment with 98% sulfuric acid. Titania nanowires with variable amount of anatase and rutile were prepared by heating to temperatures in the range 350–1000°C. The precursor as well as titania based samples were characterized by X-ray diffraction, Infrared spectroscopy, Scanning electron microscopy, High resolution transmission microscopy, Thermogravimetry, Differential thermal analysis, Evolved gas analysis and Emanation thermal analysis. The nitrogen adsorption/desorption was used for surface area and porosity determination. The photoactivity of the prepared titania samples was assessed by the photocatalytic decomposition of 4-chlorophenol in an aqueous slurry under UV irradiation of 365 nm wavelength.