The influence of fusion temperature on the defect center concentration of GeO2 glass

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Abstract
Paramagnetic resonance spectra of virgin glasses and γ‐ray irradiated GeO2 glasses were studied with the electron spin resonance (ESR) method as a function of fusion temperatures. Fusions were made in air at temperatures between 1200 and 1650 °C and cooled at constant rate. In virgin glasses, only the E′ center was detected at concentrations of about 1015/g. After a γ‐ray irradiation, a new resonance at the low‐field side (lfs) of the E′1 center and a symmetric line with g=1.91 were observed. Measurements at various temperatures, power levels, and frequencies provide a basis for resolving the overlapping resonances. We labeled the paramagnetic center causing the lfs signal the H0 center. The g values of the H0 center are the basis for attributing this center to a hole located on a nonbridging oxygen. The g=1.91 resonance is attributed to Cr5+ or M5+0 impurities in the GeO2 glasses. At constant γ‐ray dose, the H0 center concentration decreased and the E1 ‐center concentrations increased with increase of fusion temperature.