Structure study on the thermoelectric materials CexCo4Sb12 (x = 0.5, 1.0) by neutron diffraction

In order to understand the relationship between crystal structure and thermoelectric properties, the neutron diffraction patterns of the thermoelectric materials with the nominal composition Ce_xCo₄Sb₁₂ (x = 0.5, 1.0) were measured at room temperature, the data were fitted by the Rietveld profile refinement method using the Fullprof2k program. It is found that the sample Ce_0.5Co₄Sb₁₂ is composed of two phases, its major phase is CoSb₃ with skutterudite-structure and the Ce atom is not incorporated into the lattice, the impurity is monoclinic CoSb₂. In the case of Ce_1.0Co₄Sb₁₂, the major phase is filled skutterudite, about 10% of the 2a site is occupied by Ce atom, the second phase is monoclinic CoSb₂.     

蒸发器母液循环泵、过料泵泵壳泄漏分析及对策

介绍我公司氧化铝厂KESTNER蒸发器母液循环泵、过料泵泵壳的泄漏情况 ,分析泄漏原因 ,提出相应的改进措施     

Growth and optical properties of Er,Yb:YAl3(BO3)4 crystal

Single crystal of erbium, ytterbium-codoped yttrium aluminum tetraborate Er,Yb:YAl₃(BO₃)₄(Er,Yb:YAB) has been grown by the flux method. The absorption spectrum in the visible and NIR regions of Er,Yb:YAl₃(BO₃)₄ crystal are measured at room temperature and fluorescence spectrum of Er,Yb:YAl₃(BO₃)₄ crystal are also measured at room temperature, excited by 976 nm laser. Not only the strong NIR emission peaks located at 1548 nm was observed, but also the visible up-conversion luminescence has been found. The specific heat of the Er/Yb:YAB crystal at room temperature is 0.81 J/g °C.     

A method for characterization and quantification of platelet graphite nanofiber edge crystal structure

Platelet graphite nanofibers are materials produced from the decomposition of carbon monoxide and hydrogen over iron powders. The surface consists of terminated graphite edges, differing from traditional graphite materials in which basal plane graphite surfaces dominate. The 3-dimensional morphology and crystal face exposure on the nanofiber surface was determined by selected area electron diffraction studies. From orientation of the “zigzag” and “armchair” directions, the concentration of and face families on the fiber surface, along with the overall geometry and shape of the nanofibers, were determined. To overcome the problem of large aspect ratio in such materials, the fibers were cleaved along the basal plane, which was oriented perpendicular to the fiber axis. Effectively, the materials were transformed into multiple single crystal graphite structures. The cleaved samples, because of the decreased depth of field, were then observed end on using transmission electron microscopy techniques. It was found that the zigzag/armchair face ratio for most observed structures was ∼1.7/1, but some samples deviated from this ratio. Such knowledge is useful in discerning types of graphite surfaces are exposed when nanostructured carbons are used as catalysts and catalyst supports.     

Microstructure and sliding wear assessment of Co–TiC composite materials

Monolithic Co and Co based composites reinforced by TiC precipitates were fabricated by vacuum arc melting process. The ratio of hexagonal to cubic phase cobalt was affected by the presence of the TiC precipitates. The microstructure of the produced materials was also associated with the presence of TiC crystals. The TiC primary precipitates are characterised by a strong faceted morphology which is explained in terms of Jackson’s theory of crystal growth. The solidification progress was altered by the presence of the TiC crystals. The sliding wear behaviour of the produced composites was assessed in terms of wear track and debris examination and compared to that of Co29Cr5Mo alloy.     

Controlled morphologies and optical properties of ZnO films and their photocatalytic activities

ZnO films with three different microstructures including hexagonal prisms, plates and rose-like twinned crystals were fabricated using chemical bath deposition with different concentration of gelatin. The growth mechanisms of ZnO films were discussed, and the gelatin played a vital role as a polyelectrolyte capping the formation of microstructures. The photoluminescence and Raman properties were found sensitive to the crystal morphologies of ZnO films. Significantly, the photodegradation efficiencies of methylene blue under UV light irradiation in the presence of ZnO films consisted of hexagonal prisms and rose-like twinned crystals were 95% and 96%, respectively. The excellent photocatalytic activities can be ascribed to the high oxygen vacancies concentration and high percentage of polar planes, and this result was important in addressing the origin of high photocatalytic activity.     

Unprecedented preparation of bis-Schiff bases and their manganese(III) complexes with urease inhibitory activity

Two new thiocyanato-coordinated manganese(III) complexes with bis-Schiff bases have been unprecedented prepared from N-ethylethane-1,2-diamine and N-(2-hydroxyethyl)ethane-1,2-diamine as the starting materials with equimolar quantities of 4-methoxysalicylaldehyde and 3-ethoxysalicylaldehyde, respectively. It was found that the reaction can process only in the presence of manganese salts and ammonium thiocyanate. The urease inhibitory activity of the complexes was tested.     

Controllable growth of zinc oxide nanosheets and sunflower structures by anodization method

Large scale of ZnO nanosheets and sunflower structures were fabricated by anodization of zinc in (NH₄)₂SO₄ and NH₄Cl aqueous electrolytes. The products were characterized via scanning electron microscope, transmission electron microscope and X-ray diffraction analysis. Results show that the sheets are about 20–50 μm in dimension and 20 nm in thickness. The sunflower microstructures are about 400–500 μm in dimension. The possible growth mechanism is suggested on the basis of experimental results.