Gamma-irradiated fluorophosphate glasses doped with various transition metals: A spectroscopic study

The 20NaF-60P2O5-20Na2O fluorophosphate glass systems doped with 3 wt% of CoO and NiO were manufactured using traditional melting techniques. Optical parameters were investigated for the studied composites before and after irradiation by 20 kGy of gamma rays. For the studied composites, the presence of defects within the glass network can explain the decrease of the Urbach energy (Eu) due to gamma irradiation or the increase in it due to the addition of the transition metals (nickel oxide and cobalt oxide) to the base composite. After gamma irradiation, a red shift was seen in the spectrum of the dissipation factor (tan delta). According to the calculated values of volume energy loss function (VELF), and surface energy loss function (SELF), the energy lost at the surface of the composites under investigation is larger than the energy lost within the composites' constituent materials. All investigated composites demonstrated an insulating property by obtaining the values of the covalency parameter (M) less than unity. All of the nonlinear optical parameters were increased after irradiation of the studied composites, whereas the highest values were recorded for the irradiated composite doped by CoO. Following the intrinsic and extrinsic defects produced by the former oxide itself and by added modified oxide dopants inside the glassy network was important to explain changes inside the network by ESR spectra for prepared fluorophosphate composites. Moreover; defects induced inside the glass network by 20 kGy of gamma-ray have been followed to continue the ongoing study of the nature of the prepared glassy network.