Для бінарних сполук виведено вираз ефективних зарядів, залежних від числа молекул в елементарній паралелограмі, площі його перетину поперек зовнішньому полю, модулі Юнга і діелектричній проникності. Для нітридів бору були отримані наступні напівемпіричні оцінки: h-BN-0.35 і 0.09, c-BN-0.49, і w-BN-0.76 і 0.50 Ключові слова: модель точкових атомних зарядів, напівемпіричні оцінки, нітриди бору Для бинарных соединений выведено выражение эффективных зарядов, зависящее от числа молекул в элементарном параллелограме, площади его сечения поперек внешнему полю, модуля Юнга и диэлектрической проницаемости. Для нитридов бора были получены следующие полуэмпирические оценки: h-BN-0.35 и 0.09, c-BN-0.49, и w-BN-0.76 и 0.50 Ключевые слова: модель точечных атомных зарядов, полуэмпирические оценки, нитриды бора

Soluble polyurethanes containing bisphenol fragments in the chain were synthesized on base of card-type diols. The characteristics of the resulting polymers were studied t o find the kinetic regularities in the formation of these polyurethanes. The effects of temperature, duration of the reaction, initial concentration of the components in the reaction medium, and of the structure of the diols and diisocyanates were investigated. The rate constants of the reaction and the activation energy of the process were determined. Synthese und Untersuchung yon Bisphenolfragmente enthaltenden DioEen und oon Polymeren auf dieser BasisLosliche Polyurethane, die Bisphenolfragmente in der Kette enthalten, wurden ausgehend von Diolen vom Cardo-Typ synthetisiert. Die Eigenschaften der erhaltenen Polymere wurden untersucht, um die kinetischen Besonderheiten der Bildung dieser Polyurethane festzustellen. Die Einflusse von Temperatur, Reaktionszeit, Anfangskonzentration der Komponenten im Reaktionsmedium sowie der Struktur der Diole und Diisocyanate wurden untersucht. Die Geschwindigkeitskonstanten der Reaktion und die Aktivierungsenergie des Prozesses wurden ermittelt. Acta Polymerica 39 (1988) Nr. 8 446 PAPAVA, MAISURADZE et al.: Synthesis and study of diols containing bisphenol fragments

Heating a mixture of boron (impurities: carbon ∼ B50C2, boric acid – H3BO3) and tantalum (Ta) powders in nitrogen flow in a xenon high-flux optical furnace was performed. As-received powder composed of h-BN, H3BO3, TaB2, B9H11 and a number of other phases including β-rhombohedral boron, apparently, heavily doped with Ta. FT–IR examination of any sample of the material reveals the complicated vibration spectrum containing, in particular, an absorption band near 2260 cm−1. The shapes of these bands are different for samples because powders were synthesized at different temperatures. Known, that in β-rhombohedral boron lattice, there are nano-sized voids of different types, which allow an accommodation of single atoms or small groups of atoms. Theoretical calculations performed by the method of quasi-classical type yields the same value, 2260 cm−1, for the vibrations frequency of Ta atoms in D-type crystallographic voids in β-rhombohedral boron lattice. Since, Ta atoms are known to prefer accommodation just in D-voids the experimentally detected bands can be identified with localized vibrations of Ta atoms.

Results of the effect of concentrated light energy in a xenon high-flux optical furnace on transformation of boron nitride (BN) and boron (B) powders in a flow of nitrogen are presented. Raman, Auger Electron (AES), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning and transmission electron microscopes (SEM and TEM), and the measurement of band gap using transmittance technique have been employed for investigation of the properties of produced nanostructures. According Raman, AES and FTIR study the surface of all prepared nano powders is composed of BN. XRD disclosed pure amorphous boron inside particle. Gradient transformation pure boron to BN in the framework of one particle as well as layered nanostructure was observed by TEM study. Dependence of a square of the optical absorption coefficient for a deposited BN film versus the photon energy of incident light has confirmed a gradient and layered nature of the prepared BN nanostructures. * Corresponding AuthorFax: +380 (0) 44-4242131 E-Mail: sart@ipms.kiev.ua [a

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