Role of Bi₂O₃ in altering the structural, optical, mechanical, radiation shielding and thermoluminescence properties of heavy metal oxide borosilicate glasses

With the main intention of developing a transparent radiation shielding as well as a gamma dosimetric material, a series a heavy metal oxide borosilicate glass of composition (60-x) B₂O₃- 20SiO₂- xBi₂O₃- 10ZnO- 10BaO with x = 0, 5, 10, 15 mol% was prepared by melt- quench technique. The glasses obtained were all transparent, except Bi-15 sample which is opaque and black in colour. The darkening is due to thermal reduction of Bi³⁺ ions, which is clearly indicated by absorption band around 377nm. XRD patterns showed the absence of crystalline peaks even in the opaque Bi-15 sample, confirming the glassy nature of all glasses. Furthermore, the structural changes in the glasses were confirmed with density measurement and FTIR studies. The Vickers hardness test done on transparent samples proved their higher mechanical strength, along with the theoretical calculation of elastic constants. The detailed analysis of gamma and neutron radiation shielding parameters for all the glasses was done using Photon Shielding and Dosimetry (PSD) software. The results suggested that the ϒ-ray shielding capacity increased, whereas the neutron attenuation ability decreased with the successive addition of Bi₂O₃. The opacity of Bi-15 can create problem in certain applications where transparency is needed. In order to assess the possibility of transparent glasses to be used as gamma dosimeter, they were irradiated with gamma rays of 1.25 MeV and thermoluminescence (TL) glow curves were recorded. An interesting behaviour of quenching of TL intensity for initial addition and enhancement of TL intensity for further addition of Bi₂O₃ was observed. The linearity of the dose- response curve for Bi-10 sample in two regions of gamma doses 100 Gy-3 kGy and 5- 50 kGy, showcased the chances of Bi-10 sample to be used as TL dosimeter for both low and high doses.