The effect of WO3 dopant on the structural and optical properties of ZnO–P2O5 glass and the effect of gamma irradiation

Zinc phosphate glasses doped with different ratios of tungsten trioxide were prepared. Optical and infrared absorption spectra were investigated before and after subjecting the glasses to 80 kGy gamma ray dose. The base undoped zinc phosphate glass shows strong and broad UV absorption band centered at about 240 nm but with no visible bands. The WO3-doped glasses reveal the same UV absorption bands beside extra three bands at 330, 380 and 575 nm which are related to the presence tungsten ions in the pentavalent state. Infrared absorption spectra show characteristic variable phosphate groups with limited variations when introducing WO3 in the doping level up to 0.75%. Electron spin resonance measurements of the selected high doped tungsten glass indicate that mixed penta- and hexa-valent states of the tungsten ions and on gamma irradiation the pentavalent increases. The result supports the optical absorption after gamma irradiation which involves photochemical reactions in the UV region and the transformation of some W6+ to W5+ by absorbing electrons during the irradiation process.