Effects of Small Additives on Stress Build-up in Glass by Ultra-violet Irradiation: Rare Earth Oxides

The stresses built up by ultra-violet irradiation in glasses containing rare earth (Pm and Lu were not examined.) oxides were measured. The effects of the additives were classified as follows: a-group; The stresses were large when added in amounts about 0.5g oxide per 100g of the base glass, b-group; The effects of the amount added were the intermediate ones between a- and c-group, and c-group; The stresses were only slightly dependent on the amounts added. It was noted that the ions belonging to the a-group corresponded to those which show f→d or charge transfer bands in optical absorption and change valencies by light or ionizing radiation. The enhancement effect of the stress by these ions was discussed. The ions belonging to the c-group behaved similarly with the rare gas type ions (such as alkali and alkaline earth ions). They seemed to be simple fillers of the glass network.