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Ge30AsxSe70-x bulk glasses from the point of view of chemistry
Year: 2020
Type of publication: článek v odborném periodiku
Name of source: Journal of Solid State Chemistry
Publisher name: Elsevier Science Inc.
Place: New York
Page from-to: 121599
Titles:
Language Name Abstract Keywords
cze Objemová skla Ge30AsxSe70-x z pohledu chemie. U skel Ge30AsxSe70-x byla studována struktua korelována s ternárním fázovým diagramem. Na tomto základě byla vysvětlena oblast sklotvornosti tohoto systému.
eng Ge30AsxSe70-x bulk glasses from the point of view of chemistry To elucidate the chemical structure of Ge-As-Se based glasses with selenium substoichiometry, Ge30AsxSe70-x homogeneous bulk glasses were prepared and the glass-forming region was found from x = 0 up to 40. The chemical structure of these glasses was characterized by basic structural units. The structure of Ge30Se70 (x = 0) glass is based on GeSe4/2 and GeSe4 structural units and traces of selenium. When selenium is gradually replaced with arsenic AsSe3/2 and Ge(II)As(2/3 )structural units appear in the equimolar ratio with gradually increasing concentrations at the expense of the units with Ge-Se bonds. Finally, for x = 40 the glass is formed exclusively by structural units AsSe3/2 and GeAs2/3. Thus, the structure of both border glasses is based only on two structural units whereas other glasses are based on four units. For this reason, the undercooled melts of both border glasses are less stable and undergo crystallization when heated. In terms of the geometry of the basic structures, the structure for x = 0 is formed solely by tetrahedral units with germanium as the central atom, and then is gradually transformed with increasing concentration of arsenic to a structure consisting only of trigonal pyramids with arsenic as a central atom. Chalcogenide glass; Chemical structure; Raman spectroscopy; Se-77 MAS NMR; 2D correlation spectroscopy; Thermal analysis