Structural, spectroscopic, and radiation shielding properties of Pb2+-doped borate and phosphate glasses

Abstract

Lead-containing alkali/alkaline-earth borate and barium lead phosphate glasses were prepared by melt-quenching for a detailed investigation of the Pb²⁺ ions’ optical properties. UV–Vis absorption and photoluminescence spectroscopy reveal variations in the s–p transition of Pb²⁺, which are shown to correlate with the optical basicity of the host glass in both borates and phosphates. Pb²⁺ emission differs significantly for borate and phosphate glasses, as the nature of the charged sites available to accommodate Pb²⁺ cations vary. Optical basicity values were determined from the composition (Λ_th) and the measured refractive index (Λ_n). The UV-cutoff shifts toward higher wavelengths with increasing optical basicity and lead content. In borate glasses, the frequency of the stretching modes due to nonbridging oxygen atoms of trigonal metaborate species is identified to be inversely proportional to the excitation wavelength (directly proportional to the excitation energy) of Pb²⁺. Lead-containing alkali and alkaline-earth borate glasses show additional correlations between the Pb²⁺ emission wavelength and the weighted average of the field strength of the modifier(s). Complementary to the investigation of optical properties, radiation and neutron shielding parameters were calculated, suggesting the potential utility of some of the studied compositions for radiation shielding applications.