Optical and mechanical studies of borate lithium glasses doped with potassium oxide and calcium oxide

Glasses with compositions 80B2O3-20Li2O, 80B2O3-(20-x)Li2O-xK2O and 80B2O3-(20-x)Li2O-xCaO (where x = 0 to 10 in steps of 2 mol %) have been prepared using normal melt quenching technique. Structure that was investigated using X-ray diffraction has indicated the amorphous state of the prepared glasses. The density and the molar volume have been determined. Decrease in density and the increase in molar volume of the glass samples indicated the largeness of glass network upon addition of K2O and CaO. Furthermore, the optical and mechanical characterizations of these glasses were carried out. Variations in the different physical parameters such as the oxygen packing density, refractive index, dielectric constant, molar refractivity, molar electronic polarizability and metallization criterion of borate lithium glass with K2O and CaO content have been analysed and discussed in terms of the changes in the glass structure. Results show anomalies with addition of K2O and CaO confirming the changes in the rigidity and the content of non-bridging oxygens (NBOs). The Vicker’s microhardness studies reveals the anisotropy nature of the material. It further confirms that the samples belong to soft glass category. Decreases in microhardness were attributed to decreases in elastic moduli and bond strength with increasing load. The effects of composition of the glasses on microhardness are discussed.