In a series of Cs-doped tungsten oxides that underwent different degrees of reduction, new components and behaviors were found in X-ray photoelectron spectroscopy (XPS) signals of O−1s, W−4f, and Cs−3d and analyzed in terms of oxygen vacancies (V O s) and electron localization with the aid of first-principles calculations. Orthorhombic Cs 4 W 11 O 35 was reduced at high temperature to transform it to hexagonal tungsten bronze with increasing W 5+ trapped electrons, as detected in W−4f. The binding energy of W 5+ −4f showed a distinct redshift toward low saturation values that was implied to be due to W 5+ alignment on the hexagonal prismatic planes. The V O enthalpy of formation and the Bader charge calculated for each atom site supported this view, by identifying the preferred sites for V O and W 5+ on (020) in Cs 4 W 11 O 35 . The W 5+ component was newly admitted in O−1s at 531.25−531.94 eV and 532.35−533.04 eV, while the carbonation contributions were eliminated using C−1s deconvolution. In Cs−3d, a V O -related extra component was found on the high-energy side, which grew with increasing reduction time. These observations and calculations supported the proposition that electrons emitted from Cs should be delocalized, and those from V O s should be both localized and delocalized in Cs-doped tungsten oxides.
A rapid procedure of determination, without digestion, for trace metals in cow's milk was devised by the use of a polarized Zeeman atomic absorption spectrophotometer and graphite atomizers.The simplified standard addition method was employed using the sample diluted with 70 v/v % ethanol so as to prevent bumping during drying in the atomizer.Then, in order to promote the decomposition of organic matter and to unify the chemical form and valence of the metal, as well as of coexisting components, nitric acid was added to the standard metal solution to be added to the sample solution dried in the atomizer.In the determination attempted for copper, zinc, iron, lead and cadmium in milk, satisfactory results were obtained. Furthermore, this method was confirmed to be useful by comparing the result with those of other methods, such as the standard addition method and the wet digestion-solvent extraction method.The peak area mode was used for calculation. For the determination of cadmium, dilution of milk was necessary and wavelengths other than their primary resonance lines had to be used for the determination of zinc and iron.
LiMn1.5Ni0.5O4 is an excellent candidate as a cathode-active material in high-voltage lithium-ion batteries and studied using atomic resolution scanning transmission electron microscope. High-angle annular dark-field (HAADF) images obtained at [100] orientation demonstrate that Mn and Ni atoms are regularly ordered at octahedral sites in a spinel structure, in a 3:1 ratio between columns with high and low intensities. Simulations of HAADF images revealed that atomic columns including Mn exhibit a larger intensity than that by Ni columns, primarily because of the effect of the Debye-Waller factor.
We investigated the synthesis of Sr 3 SiO 5 :Eu 2+ (SSE) yellow-orange phosphors by three different gelation methods using Propylene Glycol-Modified Silane (Gelation with Sr, Eu nitrate solution, Gelation with Sr, Eu citrate solution, Gelation with SrCO 3 and Eu 2 O 3 slurry) and the effects of the synthetic methods on the main phase (Sr 3 SiO 5) purity and quantum efficiency of SSE phosphors. SSE phosphor synthesized by the nitrate solution method exhibited relatively low main phase purity and quantum efficiency due to segregation of Sr and Eu that occurred during a drying process of the synthesis. SSE phosphor with higher quantum efficiency was obtained by the citrate solution method, but decomposition of a large amount of citric acid was a problem. Obtaining a pasty white gel by adding PGMS to the slurry of SrCO 3 and Eu 2 O 3 without adding citric acid was the best way to obtain SSE phosphor having the highest phase purity and quantum efficiency with constituent elements evenly distributed. The slurry method was also effective from the viewpoint of not requiring decomposition of a large amount of organic components.
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