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Thermo‐structural characterization of (As 2 Se 3 ) 100‐x ‐(As 2 Te 3 ) x glasses for infrared optics
Author(s) -
Brandová Daniela,
Svoboda Roman
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15919
Subject(s) - differential scanning calorimetry , crystallization , crystallite , raman spectroscopy , infrared microscopy , infrared , monoclinic crystal system , materials science , infrared spectroscopy , analytical chemistry (journal) , relaxation (psychology) , glass transition , enthalpy , crystallography , spectroscopy , chemistry , crystal structure , thermodynamics , optics , physics , polymer , quantum mechanics , composite material , psychology , social psychology , organic chemistry , chromatography
Differential scanning calorimetry was used to study thermokinetic behavior of (As 2 Se 3 ) 100− x (As 2 Te 3 ) x infrared glasses (seven compositions along the pseudo‐binary were investigated). Glass‐transition kinetics was described in terms of the Tool‐Narayanaswamy‐Moynihan model and the relaxation motions were interpreted using Raman spectroscopy data. The enthalpy relaxation kinetics was found to be absolutely uninfluenced by changing Se/Te ratio. On the other hand, DSC crystallization behavior changed significantly with increasing As 2 Te 3 content: Te‐rich compositions show marked affinity toward crystallization, whereas in case of the compositions with 0‐34 mol.% As 2 Te 3 crystal growth is significantly suppressed. X‐ray diffraction analysis indicated presence of monoclinic As 2 Se 3 , As 2 Te 3 , and As 2 Se(Te) 3 phases. The complex crystallization behavior occurring in case of the Te‐rich compositions was described by superposition of two autocatalytic kinetic signals. Based on the information from infrared microscopy the two overlapping crystallization processes can be attributed to the respective formations of spherulitic and needle‐shaped crystallites. Best glass stability was identified in case of the (As 2 Se 3 ) 66 (As 2 Te 3 ) 34 composition, which appears to be a potential candidate for optic applications in the far‐infrared region of the spectrum.