Structural Study of Germanate Glasses Irradiated with γ-Rays and Thermal Neutrons

Abstract

Abstract 119Sn Mössbauer study of 60Co-γ ray and thermal neutron irradiated potassium germanate glasses containing a small amount of SnO2 has been performed to investigate the structural change of the glasses. The γ- and the thermal neutron-irradiation results in a disappearance of the distinct composition dependence of the Mössbauer parameters (quadrupole splitting and linewidth) observed before the irradiation. DTA measurement of the irradiated glasses also reveals drastic decreases in glass transition temperature (Tg) amounting to 20–120 °C and a simultaneous disappearance of the distinct composition dependence of Tg observed before the irradiation. This suggests a disruption of the chemical bond between germanium and oxygen atoms constituting GeO6 units. On the other hand, Mössbauer measurement at lower temperatures reveals that a parameter of intermolecular force constant (θ2M) obtained from the temperature dependence of the absorption area undergoes little change by the irradiations. This suggests that the irradiations bring about little changes in the ionic bond and the interatomic distance between tin and oxygen atoms, and that the irradiated germanate glasses can still be regarded as polymers from the lattice vibrational point of view.