ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 58, (2) 95 - 98 (2014)


THERMODYNAMIC MODEL AND STRUCTURE OF As2S3-As2Se3 GLASSES BASED ON THE MCR ANALYSIS OF RAMAN SPECTRA
 
Liška Marek 1, Chromčíková Mária 1, Holubová Jana 2, Černošek Zdeněk 2
 
1 Vitrum Laugaricio - Joint Glass Center of IIC SAS, TnUAD, FChPT STU, and RONA, Študentská 2, Trenčín, SK-91150, Slovakia
2 Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, CZ-53210, Czech Republic

Keywords: Glass structure, Thermodynamic model, Aarsenic trisulfide, Aarsenic triselenide
 

Raman spectra and structure of six glasses with the composition of xAs2S3∙(1 - x)As2Se3 (x = 1; 0.75; 0.667; 0.50; 0.25; 0) were studied. In our previous work the Raman spectral data were interpreted on the basis of the Shakhmatkin and Vedishcheva thermodynamic model, 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 existence of mixed trigonal pyramids of the type As2S3-xSex. In the present work an alternative simple thermodynamic model was proposed based on two equilibrium reactions leading to formation of two types of mixed As2S3-xSex (x = 1, 2) pyramids. The results of multivariate curve resolution (MCR) analysis of the measured spectra were interpreted as proportional to the molar fractions of four system components: As2S3, As2Se3, As2SSe2, and As2S2Se. Using the nonlinear regression treatment the reaction Gibbs energies were optimized by minimization 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 behavior. It was found that the optimized values of reaction Gibbs energies fit the MCR data with acceptable accuracy.


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