The calcium borate added with zinc oxide glass samples with chemical formula 20CaO-(80-x)B2O3-xZnO (where x=0, 5, 15 and 20 mol%) were prepared by the melt quenching technique. Glass samples were melted at 1,200C for 3 h and annealed at 500C for 3 h. Glasses density decreases, while molar volume increase with increment of ZnO concentration. Based on the transmission and absorption spectra obtained, the direct and indirect optical band gap, as well as the Urbach energy were calculated. The

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... cal band gap expand with increasing of ZnO concentration that probably represents the NBOs located in glass network. Urbach energy increase with increasing of ZnO concentration due to the defects produced within the localized states. The optical basicity and polarizability of glass samples have been investigated in this work.