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Information × Registration Number 0211U006599, 0109U007239 , R & D reports Title Self-organization in chalcogenide glass-forming systems popup.stage_title Head Shpotyuk Oleg, Доктор фізико-математичних наук Registration Date 13-05-2011 Organization Scientific Research Company "Carat" popup.description2 It is shown from the quantum-mechanical calculations that structure of the As-Se binary system built by pyramids which interconnected through the selenium chains in full agreement with chain crossing model. Absence of the physical ageing combination of the basic structural units as optimally-coordinated network with nc = 3 (realized in the glass of stoichiometric composition As2Se3) are chosen as criterion for self-organization of glasses. It is shown that the chain crossing model requires some adjustments in the case of AsxSe100-x system, because length of Sen chains between two atoms of As could be changed in one atom of Se being Sen+-1 with ~ 10% probability . This change could be caused by nonideal conditions of the glass preparation or processing (photo-induced effects, ageing, etc.). It has not significant value for long chains of Se, playing the important role for the compositions with three or more Se atoms in the chain (25 < x < 40). The methodology of the first principle calculations for the AsxSe100-x system was considered. The structure of GexSe100-x glass with x < 12 is defined by chain crossing model (with an accuracy of ~ 5-6 %), by combination of chain crossing and cluster modelsin the range of 12 < x < 20, and only the cluster model for x > 20. Cluster model is based on energy fovarablility of formation of the structural fragments of high-temperature crystalline GeSe2 modification consisted by two edge-shared and four corner-shared tetrahedra. Excess of Se atoms (in according to the chemical composition) are connected to the Se-Se dimer of the such cluster complex or included into the bridges between clusters. It is shown that topological self-organization in the terms of optimally coordinated network is not observed in the GexSe100-x glasses. Pseudo self-organization is observed as combination of over-constrained cluster fragments connecting via optimally-coordinated Ge-Se-Se-Ge bridges in composition with x > 20. Provided quantum-mechanical calculations shows evidence of more energy utility of such a combination. Product Description popup.authors Балицька Валентина Олексіївна Бойко Віталій Теодорович Ваків Микола Михайлович Головчак Роман Ярославович Кавецький Тарас Степанович Клим Галина Іванівна Шпотюк Михайло Володимирович popup.nrat_date 2020-04-02 Close