Structural characterization of ZnSO4-K2SO4-NaCl glasses.

Glasses with compositions x NaCl-(50- x /2)K 2 SO 4 -(50- x /2)ZnSO 4 , x = 0 to 30 (in mol%), were characterized via vibrational spectroscopy and X-ray pair distribution function (xPDF) analysis. The xPDF's were modeled using Empirical Potential Structure Refinement (EPSR). From the modeled xPDF, the deconvoluted xPDFs were obtained along with cation-anion coordination numbers. The sulfate environment was elucidated through analysis of the vibrational spectroscopy paired with xPDFs. As determined via these techniques, the SO 4 2− oxyanions remain as distinct tetrahedra and dominate the overall structure of these ionic glasses, even with up to 30 mol% addition of NaCl. Addition of NaCl lowers the glass transition temperature (T g) of these materials and increases the temperature between T g and the first crystallization temperature upon heating, as determined by differential thermal analysis (DTA). The composition-dependent xPDFs indicate that chloride ions are distributed equally and increasingly around Zn, K, and Na cations as x increases. • Ionic glasses in the system NaCl-ZnSO 4 -K 2 SO 4 were synthesized and characterized. • Sulfate units are non-bridging tetrahedra according to PDF and Raman • Increasing NaCl addition decreases the glass transition temperature. • Bond distances in the glass are similar to those in crystalline sulfate salts. [ABSTRACT FROM AUTHOR]