Oxygen Reactions at the Interface of Nonstoichiometric Fluorides LaF3 and CeF3 with Chemically Modified Electrodes

The oxygen reaction at the interface LaF₃(CeF₃)|electrode,O₂(g) is studied in air on Pt and C electrodes and electrodes modified by supported oxides of Co, Sr, and/or La on C, Si, or Pt substrates. The experimental methods used are voltammetry with a linear potential change and stripping voltammetry and cyclic voltammetry. The voltammetric response is dependent on the nature of solid electrolyte and electrode, the balance between the substrate and active agent, and on the conditions of thermal treatment of electrodes. Mobile oxygen forms are discovered at interfaces CeF₃|C (Co _x O _y ), ₂ ([C] : [Co] = 1 : 10, 1 : 20); CeF₃|C (Co _x O _y ), ₂([C] : [Co] = 1 : 10); and CeF₃|Pt (Co _x O _y ), O₂([Pt] : [Co] = 1 : 40). The peak current I _pa in the anodic curves increases with extending the limit of cathodic potential scan E _rc. The peak current I _pc in the cathodic curves increases with extending the limit of anodic potential scan E _ra.     

Composition of oxygen precipitates in Czochralski silicon wafers investigated by STEM with EDX/EELS and FTIR spectroscopy

In this work, we investigated the stoichiometry of oxygen precipitates in Czochralski silicon wafers. The thickness dependence of the Cliff–Lorimer sensitivity factor for the silicon/oxygen system was determined and applied for the investigation of the stoichiometry of oxygen precipitates by EDX. The results show that both plate‐like oxygen precipitates and a transitional form between plate‐like and octahedral precipi‐ tates consist of SiO₂. This was confirmed by EELS low loss spectra where the typical spectrum for amorphous SiO₂ was observed. Moreover, the absorption band of plate‐like precipitates at 1227 cm^–1 was found in the low temperature FTIR spectrum. It was demonstrated that this band can only be simulated by the dielectric constants of amorphous SiO₂. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

N-Polyfluoro(trimethylsilyl)ethyl azole derivatives

A facile synthetic route to N-polyfluoro(trimethylsilyl)ethyl azole derivatives was developed starting from N-bromo(chloro)polyfluoroethyl-substituted azoles. The silanes thus obtained were reacted with various electrophiles in the presence of the fluoride ion to yield the corresponding fluorinated carbinols, ketones, carboxylic acids, and methyl dithiocarboxylates as well as N-pentafluoroethylbenzimidazole.     

Surface potential and surface tension of aqueous 2-halogenoethanol-ethanol solutions

The surface properties of aqueous 2-fluoro-, 2-chloro-, 2-bromoethanol-ethanol mixtures were studied by surface tension measurements, applying the drop weight method, and by surface potential using the flowing jet method. The addition of ethanol to 2-halogenoethanol solutions causes a synergetic effect on surface tension. In the case of surface potential the synergetic influence exists only in the mixtures of ethanol-2-fluoroethanol. The studies on the surface interactions of the adsorbed molecules of particular components in the mixed film were carried out by the Rosen and Hua method. The weak interaction between adsorbed molecules was observed.     

сОДЕРжАНИь РАБОт, ОпУБлИкОВАННых тОлькО В ЧЕшскОМ ИжДАНИИ НАстОьЩЕгО жУРНАлА

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Abstracts of Papers which have appeared only in the Czech Edition of this Journal

     

On some properties of almost-analytic tensors in an *O-space

Summary We consider an *O-space which is a kind of almost-Hermitian space. There is stated a theorem, that is, in a compact *O-space a skew-symmetric covariant almost-analytic tensor is closed. From this theorem, we get many important properties of almost-analytic tensors in an almost-K?hlerian space or a K-space and an interesting result related to the Lie derivative.