The effect of RO (R = Mg, Ca, Ba and Zn) on physical properties of Na2O/Al2O3/B2O3/SiO2 glasses for the preparation of gradient index micro lenses

Glasses in the system Na2O–Al2O3–B2O3–SiO2 doped with MgO, CaO, BaO or ZnO (concentrations: 2.5%–5 mol%) were melted from the raw materials and studied with respect to their densities, hydrolytic durabilities, crystal growth velocities, specific ionic conductivities, refractive indices, Abbe numbers and optical transmissions. The samples were ion exchanged in a NaNO3/AgNO3 salt melt in order to determine the Na+/Ag+ interdiffusion coefficients and the refractive indices, Abbe numbers and optical transmissions of the ion exchanged silver containing glasses. Glasses doped with ZnO are advantageous for the production of gradient index lenses due to their improved chemical durability and smaller crystal growth velocities at viscosities in the range of 105–106 dPa s. The optical properties of these glasses are similar to those of glasses without RO.