Abstract
Accurate refractive indexes of Na2O-GeO2 glasses containing 5-30mol% Na2O were measured in the wavelength range of 0.334 to 1.710μm using the minimum deviation method. The influence of glass structure on the refractive index and its dispersion has been discussed in terms of the number of the oxygen ion in a unit volume and the apparent refractivity of the oxygen ion. With the addition of Na2O, the refractive index nd increased at 5<Na2O<15mol%, showed a maximum around 15mol% Na2O, and decreased with further addition. The Abbe number vd decreased monotonically. The variations of nd and vd with Na2O content were related to the oxygen coordination number of Ge ions.
