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Thermodynamic model and structure of As2S3-As2Se3 glasses based on the MCR analysis of Raman spektra
Autoři: Liška Marek | Chromčíková Mária | Holubová Jana | Černošek Zdeněk
Rok: 2013
Druh publikace: ostatní - článek ve sborníku
Název zdroje: Book of abstracts - 2nd Central and Eastern European Conference on Thermal Analysis and Calorimetry
Název nakladatele: Academica Greifswald
Místo vydání: Greifswald
Strana od-do: 120-120
Tituly:
Jazyk Název Abstrakt Klíčová slova
eng Thermodynamic model and structure of As2S3-As2Se3 glasses based on the MCR analysis of Raman spektra Raman spectra of six glasses with the composition of xAs2S3?(1-x)As2Se3 (x = 1, 0.75, 0.667, 0.75, 0) were studied. In our previous work the spectral data were interpreted on the basis of the Shakhmatkin and Vedishcheva thermodynamic model (TDM), where the glass was treated as an ideal solution of five components, namely: As2S3, As2Se3, As2S2, AsSe, and Se. The lack of mixed S-Se compounds in the model does not allow the interpretation of the measured spectra taking into account the experimentally proved existence of mixed trigonal pyramids of the type AsS3-xSex. In the present work an alternative TDM was proposed based on two equilibrium reactions leading to formation of two types of mixed AsS3 xSex pyramids.The results of multivariate curve resolution (MCR) analysis [5] of the measured spectra were interpreted as proportional to the molar fractions of four components As2S3, As2Se3, As2SSe2, and As2S2Se. Using the nonlinear regression treatment the reaction Gibbs energies, delta Gr,1 and delta Gr,2 were optimized by minimisation of the sum of squares of deviation between the MCR data and the equilibrium amounts of the systems components. The equilibrium system composition was calculated at experimentally determined glass transition temperature assuming the ideal behaviour. It was found that the optimised values of delta Gr fit the MCR data with acceptable accuracy. Raman spectra; thermodynamic modelling; multivariate curve resolution