EFFECTS OF LOW CONCENTRATIONS OF RARE EARTH OXIDES UPON REFRACTIVE INDEX AND DENSITY OF A LEAD GLASS

摘要

Minor additions of rare-earth oxides have been found to have effects upon density and refractive index of a lead sili¬cate glass dependent upon ionic size of the rare-earth ion. A generalized effect for the whole series is diagrammatically pre¬sented and is postulated as due to a sequential polarizing and deforming effect upon the lead silicate lattice. Scandium and lanthanum demonstrate anomalies