Effect of Cr2O3 on Solubility and Thermo-Physical Properties of BaO-CaO-Al2O3-B2O3-SiO2 Glass System

BaO-CaO-Al2O3-(10-x)B2O3-xCr(2)O(3) SiO2 (BCABS), where 1.0 <= x <= 3.5, (mol%) glasses were prepared by melt-quench technique. Glass samples were characterized for density, microhardness, thermal expansion coefficient and glass transition temperature. Scanning electron microscopy was used to see the homogeneity/solubility of Cr2O3 in this glass system. UV-VIS absorption measurements were carried out to see the Cr speciation in the glass samples. Density values were found to vary from 3.97 to 3.92 g/cc and microhardness values varied from 283 to 503 kg/mm(2). Glass transition temperature increased from 635 to 671 degrees C while TEC value found to varies from 8.3 to 11.1x10(-6)/degrees C(30-300) with Cr2O3 content. SEM study revealed phase separation in these glasses. From absorption studies we infer the presence of small amount of Cr (VI) along with Cr(III) oxidation state.