FORMATION AND PROPERTIES OF RARE-EARTH GALLIOGERMANATE AND ALUMINOGERMANATE GLASSES

The density, glass transformation temperature and hardness of these gl asses increase with increasing atomic number and concentration of the rare earth ion present in the glass, while the thermal expansion co-ef ficient is independent of rare earth identity. Glasses containing alum ina are less dense and have lower refractive indices and thermal expan sion coefficients than those containing gallia, but they are also more refractory and harder. The magnetic susceptibility and Verdet coeffic ients of these glasses are consistent with other studies of glasses co ntaining various rare earth ions. These glasses exhibit excellent chem ical durabilities in water.