Gamma ray interaction with lithium borate glasses containing WO₃

471-480Glasses from the system of undoped lithium diborate and WO3-doped were synthesized by the usual melting and annealing techniques. UV-visible absorption spectra of the prepared sample were measured before and after successive gamma irradiation. Undoped glass reveals strong UV absorption spectrum which is related to the presence of unavoidable trace iron impurity. The presence of tungsten ions in this glass system is observed to impart no colour or marked changes in the absorption spectrum of the host glass suggesting the presence of tungsten ions mostly as W6+ species. Gamma irradiation produces extended induced bands in the UV-visible regions in the undoped and WO3-doped glasses. These induced bands are related to the presence of intrinsic defects already present in the host lithium diborate glass and extrinsic defects due to the presence of both trace iron impurity and tungsten ions. Infrared absorption spectra reveal specific vibrational bands due to characteristic borate network beside modifier lithium ions (Li+) and tungsten groups. Raman spectra confirm the IR results regarding the presence of tungsten ions mainly as WO6 groups due to the oxidizing nature of the host glass. Tungsten ions are seen to cause shielding or retardation of the growth of the induced bands by gamma irradiation

Optical and infrared absorption of gamma irradiated ternary silicate glasses containing NiO

651-666<span style="font-size: 15.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">The optical and infrared absorption spectra of ternary silicate glasses containing NiO were studied systematically, as function of glass composition. The same properties were measured after successive gamma ray irradiation. The induced spectra and the rate of formation of the intrinsic defect of the base glass and the extrinsic detect due to the nickel ion were calculated. The experimental optical results were analysed and explained by assuming that, nickel exists in glass as divalent Ni ions in two different states of coordination, namely, octahedral and tetrahedral. The infrared spectra of the doped glasses reveal the same spectra of the undoped glasses retaining the main vibrational bands which indicate that the dopant oxide has no effect on the main structural building groups. The rates of formation and annihilation of the color centers produced by gamma irradiation are believed to approach saturation or equilibrium with prolonged irradiation. </span