Crystal structure and electrochemical behaviors of Pt/mischmetal film electrodes

The Ml(La-rich mischmetal) films with a thin Pt layer on the substrate of chemically coarsen ITO glass or silicon slices were prepared by magnetic sputtering technique. The crystal structure and surface morphology of the films were investigated by X-ray diffraction(XRD) analysis and atomic force microscopy(AFM), respectively. The electrochemical hydridation/dehydridation behaviors of the films in KOH solution were studied by using cyclic voltammagraph and electrochemical impedance spectrum(EIS) as well. The AFM results show that the Pt cover layer on the Ml films is of island structure with a grain of 150200 nm in size. The presence of a thin Pt layer can provide sufficient high electrocatalytic activity for the electrochemical charge-transfer reaction. The electrochemical reduction and oxidation reaction occur on the Pt layer, and the diffusion of H into the Ml film is the rate-controlled step. The Pt coatings also act as protective layers, preventing oxidation and/or poisoning of the underlying Ml films in air.

Synthesis, Bioactivity, and Crystal Structure Analysis of 2-(3-Oxobenzo[d]isothiazol-2(3H)-yl)ethyl Benzoates

Fifteen novel 2-（3-oxobenzo[d]isothiazol-2（3H）-yl）ethyl benzoates were synthesi- zed by the condensation of 2-（2-hydroxyethyl）benzo[d]isothiazol-3（2H）-one with substituted benzoic acids in dichloromethane. All the compounds were characterized by elemental analysis, IR, ESI-MS and 1H NMR. The crystal structures for 2-（2-hydroxyethyl）benzo[d]isothiazol-3（2H）-one （2） and 2-（3-oxobenzo[d]isothiazol-2（3H）-yl）ethyl 2-methoxybenzoate （30） have been determined by X-ray crystal structure analysis. Compound 2 （C9H9NO2S） crystallizes in the monoclinic system, space group Pn with a = 10.552（3）, b = 7.849（2）, c = 10.765（4） A, β = 103.128（4）°, V= 868.3（5） A3, Mr = 195.24, Dc = 1.493 Mg.m-3, μ = 0.33 mm-1, F（000） = 408, Z = 4, R= 0.0314 and wR= 0.0628. Compound 30 （C17H15NO4S） crystallizes in the triclinic system, space group P1 with a = 8.028（2）, b = 9.300（2）, c = 10.430（3）A, V= 752.1（3）A3, Mr = 329.36, D,= 1.454 Mg.m-3, p = 0.24 mm-1, F（000） = 344, Z = 2, R = 0.0377 and wR = 0.0904. The preliminary biological test indicated that the title compounds show better growth inhibitory activity against the gram-positive bacteria than the gram-negative bacteria.

Electrical and Mechanical Properties of PMMA/nano-ATO Composites

Conducting nanocomposites of poly （methyl methacrylate） （PMMA） and antimony doped tin oxide （ATO） were prepared by solution blending. The influences of ATO content on the electrical conductivity, thermal stability, and mechanical properties of the nanocomposites were investigated. A homogeneous dispersion of silane coupling agent modified ATO was achieved in PMMA matrix as evidenced by scanning electron microscopy. The resultant PMMA/silane-ATO nanocomposites were electrically conductive with significant conductivity enhancement at 4 wt pct. It was found that the composition at 4 wt pct ATO gave the higher tensile strength. Furthermore, it gave the largest elongation at break value among all the compositions. Thermal stability of the nanocomposites was remarkably enhanced by the incorporation of silane-ATO.

Influence of composition and heat-treatment on damping capacity of Cu-Al alloys

The compositions,structures and properties of four kinds of Cu-Al alloys with different constituents were researched by means of optical microscopy,scanning electron microscopy,X-ray diffractometry and damping detection. The structures and properties of Cu-11Al-5Mn-RE experienced different heat-treatment processes were also studied. The results indicate that the damping capacity and microstructure of the alloys are improved by adding Mn and RE elements. Cu-11Al-5Mn-RE obtains the best comprehensive physical performance because of the cooperation of Mn and RE elements. Aging at 200 ℃,the damping capacity gets to the maximum. At 400 ℃,its mechanical property decreases while its damping capacity still remains,indicating its resistance to martensite decomposition and aging at moderate temperature.

Crystal structure and switchable optical properties of yttrium hydride films covered by palladium layer

The palladium/yttrium films were prepared using magnetron sputtering technique. The changes of crystal structure, morphology and optical properties of the films during the hydrogen absorption/desorption process were investigated. The results of SEM and AFM analysis show that yttrium films have columnar structure, and the Pd cover layers on the surface of the yttrium films are composed of nanometer-sized Pd particles, which contain a large amount of smaller crystalline grains. During the gas hydrogen absorption/desorption process, YH3 and YH2 hydrides form on the sites of Pd grains contacting with Y grains. Upon hydrogenation, YH3 hydride forms and the switchable optical properties can be observed. The light transparency of the films increases with the increasing of hydrogen loading time and the light wavelength, and the absorption limitation occurs at λ=400 nm. Upon dehydrogenation, YH3 hydride dissociates into YH2 hydride, and the maximum transparency occurs at λ=689 nm.

Photoelectrochemical characteristics of AB_5-type hydrogen storage alloy modified with SrTiO_3 photocatalyst

Perovskite-type SrTiO3 powders were prepared by using strontium acetate, tetrabutyl titanate and sodium hydroxide via direct hydrolysis-precipitation process. AB5-type hydrogen storage alloy（HSA） electrodes modified with SrTiO3 powders were prepared and the photoelectrochemical characteristics of the as-prepared electrodes were investigated. The results of cyclic voltammograph show that the current of reduction peak increases remarkably under the light irradiation. The obvious photochargeable properties are obtained for the hydrogen storage alloys modified with Perovskite-type SrTiO3 powders. During photocharging process, the potential of the electrode shifts quickly to negative direction and a potential plateau occurs. HSA electrode modified with SrTiO3 powders prepared by direct hydrolysis-precipitation process gives the higher potential of about -0.90V（vs Hg/HgO） under the light irradiation. SEM observation discloses that a large amount of microcracks occur on the surface of the electrode after photocharging process, which is caused by the formation of hydride in the bulk of electrode.

Bridgman growth of LiYF_4 single crystal in nonvacuum atmosphere

Using LiF and YF3 as starting materials,we prepare feed material from fluorides according to the molar ratio of LiF：YF3=51.5：48.5.The anhydrous LiYF4 polycrystalline material is synthesized via the fluoridation process with a dried HF flow at elevated temperature.By charging the feed material and adding a small amount of active carbon powder in a sealed platinum crucible,the crystal can be grown via the vertical Bridgman method in a nonvacuum atmosphere.This is possible because the oxidization and volatilization of the melt is avoided.Using optimum conditions,that is,a growth rate of 0.5-0.6 mm/h and a temperature gradient of 25-30℃/cm across the solid-liquid interface under a furnace temperature of 920-930℃,the colorless crystal LiYF 4 with the size of φ25 × 50 （mm） is successfully grown.The optical transmittance of the crystal is as high as 85% above the absorption edge at 190 nm.The induced absorption bands are observed below 700 nm in the transmission spectrum after the crystal is subjected to a high dose of γ-ray irradiation.