Thr density of glass is usually considered as an important physical parameter and any observed changes in density value directly indicate the differences in the selected glass chemical composition and in turn the glass network structure. The molar volume of the glass systems under study changes with Cr2O3 content in a specific manner (Fig.1 ). This variation of VM can be divided into three regions. In the first region, VM increases with an increase in Cr2O3 content up to 0.02 mol%, which is attributed to the decrease in the number of non-bridging oxygen (NBOs). A further addition of Cr2O3 may accordingly result in an extension of the glass network, reflecting that the inter-atomic spacing is expanded [28]. In the second region, the molar volume increases slightly. In the studied glass where content of Cr2O3 are 0.02 – 0.05 mol %, Cr2O3 act as a partly of network former, packing decreases and molar volume increases.