Effect of Sm-, Gd-codoping on structural modifications in aluminoborosilicate glasses under β-irradiation

Two series of Sm-, Gd-codoped aluminoborosilicate glasses with different total rare earth content have been studied in order to examine the codoping effect on the structural modifications of β-irradiated glasses. The data obtained by electron paramagnetic resonance (EPR) spectroscopy indicated that the relative amount of Gd3+ ions located in network former positions reveals a non-linear dependence on the Sm/Gd ratio. Besides, codoping leads to the evolution of the EPR signal attributed to defects created by irradiation. The superhyperfine structure of boron oxygen hole centres EPR line becomes less noticeable and less resolved with the increase of Gd. This fact manifests that Gd3+ ions are mainly diluted in the vicinity of the boron network. By Raman spectroscopy, we showed that the structural changes induced by the irradiation also reveal non-linear behavior with the Sm/Gd ratio. In fact, the shift of the Si–O–Si bending vibration modes has a clear minimum for the samples containing equal amount of Sm and Gd (50:50) in both series of the investigated glasses. In contrast, for single-doped glass there is no influence of dopant’s content on Si–O–Si shift (in the case of Gd) or its diminution (in the case of Sm) occurs, which is explained by the reduction process influence. At the same time, no noticeable effect of codoping on Sm3+ intensity as well as on Sm2+ emission or on Sm reduction process was observed.