Mn4+ concentration effect on spectral properties of lithium-germanate glass-ceramics

A series of lithium-germanate glasses with different manganese concentration is synthesized. Li2Ge7O15 nanocrystals nucleate in the glass matrix via standard volume crystallization technique thus obtaining lithium-germanate glass-ceramics. The glass-ceramics possess intense emission near 660-670 nm under two-band excitation at 330 and 450 nm. The luminescence lifetime is 550 μs for 0.05 mol.% MnO2-doped glass-ceramics. The glass-ceramics obtained can be used as a source of deep-red radiation.

Effects of Reducing PbO Content on the Elastic and Radiation Attenuation Properties of Germanate Glasses: A New Non-toxic Candidate for Shielding Applications

This work presents a detailed study on the effects of reducing PbO content on the elastic and radiation shielding properties of germanate glasses described by the chemical formula 50GeO2-(50-x)PbO-xZnO, where x between 0 and 50 mol % with step of 10. A theoretical analysis based on Makishima-Mackenzie's theory (MM-theory) was employed to obtain the elastic moduli of the studied glass specimens. Moreover, the Monte Carlo simulations were applied via Geant4 platform to assess the radiation shielding ability of the GeO2-PbO-ZnO glass system by evaluating several fundamental properties such as gamma and neutron transmission factors, total cross sections, effective atomic numbers, 1/e penetration depths, and exposure buildup factors. We found that the bulk elastic modulus increased from 50.751 GPa to 85.389 GPa as the PbO content increased from 50 mol % to 0. The results of the linear attenuation coefficient show that the cross sections of (σ)PE, (σ)CE, and (σ)pp dominates the photon attenuation at 0.15 ≤ E ≤ 0.08; 0.8 < E < 8, and 8 < E < 15 MeV respectively. Moreover, the present glasses have superior photon absorbing capacity compared to ordinary and barite concrete; RS-253-G18 and RS-360 commercial glass shields. This suggests that the GeO2-PbO-ZnO glass system can be used as a non-toxic shielding material in the nuclear facilities.