An intrinsic photoluminescence in tellurite glasses was suggested to be caused by intrinsic defects such as Te–Te bonds and bi-coordinated Te. The defects were due to O vacancies which were created during glass melting. Up to 0.5wt% in volatilization loss from the melt occurred, and this corresponded to a loss of up to 2.5at% loss with respect to the total at% of O. Thus, for every 100 O atoms in the melt, 2.5 were missing.

Intrinsic Defects and Glass Stability in Er3+-Doped TeO2 Glasses and the Implications for Er3+-Doped Tellurite Fiber Amplifiers. V.K.Tikhomirov, A.B.Seddon, D.Furniss, M.Ferrari: Journal of Non-Crystalline Solids, 2003, 326-327, 296-300