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  • Author or Editor: V. Koval x
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Abstract  

The radioactive kryptonate of silver has been prepared by ion bombardment. Some possibilities of its uses in analytical chemistry are reported. The influence of different solutions on Ag(85Kr) has been studied with respect to the use of kryptonate in the role of an end-point indicator in volumetric determination (determination of Ba2+ with the titrant K2Cr2O7) and in the technique of calibration curves [determination of HCl, Cr2O 7 2− and V(OH) 4 + ].

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Authors: G. Zagorowsky, G. Prikhod'ko, V. Ogenko and G. Koval'chuk

Abstract  

The kinetics of the interaction between lithium carbonate and silica with various degrees of dispersion was investigated by TG and DTA methods. It was found that the utilization of pyrogenic silica with a specific surface area of about 300 m2g-1 instead of aerosil with one of 175 m2g-1 leads to an increase of the reaction rate between lithium carbonate and silica, which depends on the formation and growth of lithium orthosilicate crystals in the first stage, and is conditioned by the diffusion of lithium and oxygen ions through the lithium orthosilicate layer formed at temperatures above 800 K. This supposition is supported by the kinetic analysis results obtained with the use of the different models. The optimal regime of heating is recommended.

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Authors: V. Koval, Y. Yasievich, M. Dusheyko, A. Ivashchuk, O. Bogdan and Y. Yakymenko

Silicon nanocomposites (nc-Si) with rare earth metals (REM) were synthesized by electron-beam evaporation. The structure of nanocomposites was studied by atomic-force microscopy. The size of nanocrystallites was about 10–40 nm. Also chemical composition of obtained material was examined. The distribution of rare earth elements (REE) was uniform in film thickness, but it was characterized by a presence of maximum peak at the interface film-substrate. In the work the electrical and optical properties of nanocomposites Si:REE were investigated. Silicon nanocomposites with Eu or Y were characterized by high sensitivity to visible radiation. The ratio of dark to light resistance was achieved to 2 orders of magnitude, making this material very promising to use in thin-film photosensors. After deposition of nanocomposites Si:REE on silicon substrate, the heterojunction was formed at the interface film-substrate, for which the sensitivity to visible radiation was observed too (1–2 mA/lmV). Also, the presence of photovoltaic effect in such structures was shown, so they can be the basis of cheap thin-film solar cells, using the relevant design solutions.

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