Gamma ray interactions with MoO3-doped lead phosphate glasses

Abstract

The UV–Visible, Fourier transform infrared (FTIR) and Raman and electron spin resonance (ESR) spectra of undoped lead phosphate and MoO3-doped glassy samples have been investigated. The UV–VIS absorption spectra were re-measured after successive gamma irradiation. Before irradiation, undoped sample exhibited strong ultraviolet absorption, which was attributed to co-absorption due to trace iron impurities (mainly Fe3+ ions) and lead Pb2+ ions. With the introduction of MoO3 in progressive amounts, extra visible bands were recorded at about 400–440, 540, 750 and 870 nm. These bands are most likely correlated with the presence of Mo3+, Mo4+ and Mo5+ ions in the host glass. In the undoped specimen, gamma irradiation produced UV absorption bands that increased slightly with irradiation but no visible bands were recorded. Samples containing high MoO3 content showed some resistance to irradiation with no bands in the visible region being observed. FTIR absorption spectra of the undoped and MoO3-doped samples revealed the formation of metaphosphate and pyrophosphate structural units. Highly MoO3-doped samples exhibited additional bands due to molybdate groups. Raman and ESR spectra were in agreement with UV–VIS and IR data, indicating the presence of molybdenum ions in lead phosphate glass, as Mo3+, Mo4+ and Mo6+ with different ratios. However, such glassy systems favor the trivalent species.