Investigation of structural, optical and radiation attenuation properties of B2O3-TeO2 glass system doped with different heavy oxides

In this research, a borotellurite glass system doped with different heavy oxides for use in radiation shielding applications was studied. With this motivation, initially, xB2O3- (100-x) TeO2, x: 0, 5, 10, 15, 20, 25 ve 30 mol%; then, yBi2O3- [(100-y) ((xB2O3- (100-x) TeO2))], y: 0, 5, 10, 12.5, 15, 17.5, 20 ve 25 mol%; and finally, (100-z) [yBi2O3- ((100-y) (xB2O3- (100-x) TeO2))]- zHMO, z: 5 mol% and HMO: Gd2O3, Ta2O5, Nb2O5, La2O3, Sm2O3, glass formulations were designed as double, triple and quadruple systems. Glass series coded BT (BT5 to BT30), BT20-Bi (BT20-Bi0 to BT20-Bi25) and BT20Bi10-HMO (BT20Bi10-Gd5 to BT20Bi10-W5) were subjected to weighing, mixing, melting, forming and annealing steps, and eventually the samples were successfully synthesized. The synthesized glass series was subjected to some analyzes in terms of material characterizations and radiation shielding ability. Thus, physical, structural, thermal, optical, and radiation attenuation properties were revealed. Within the scope of physical properties, it was observed that the density values varied between 4.6504 and 5.5541 g.cm-3; hence, the density could be increased with increasing heavy oxide addition. In terms of structural properties, the all BT series, BT20Bi5, BT20Bi10, BT20-Bi12.5, BT20Bi10-Ta5, and BT20Bi10-La5 samples exhibited amorphous structure, while crystal phase formations were detected in the remaining. Further, by examining the bond structures and vibration modes, basically, B-O, B-O-B, Te-O, Te-O-Te, O-Te-O, and Bi-O bonds were found. Within the thermal properties framework, studies conducted specifically for the BT series observed that the glass transition point varied depending on different heating rates. That is, it generally altered between 321 and 348 ⁰C. Moreover, by carrying out crystallization kinetics studies, the activation energy required for crystallization and the activation energy required for viscous flow were calculated based on Ozawa, Kissenger, and Augis-Bennet methods. They were found to be between 161.5 and 303.2 kJ/mol and 65.7 and 596.9 kJ/mol, respectively. According to the studies carried out within the optical properties, it was shown that the absorption curves decrease due to different heavy oxide additions. Based on absorption spectra, the energy band gap and refractive index values showed changes in parallel. The energy band gap was calculated to be lower than 3.50 eV, and the refractive index was higher than 2.30. After material characterization tests, it was concluded that BT20, BT20-Bi10, and BT20Bi10-Ta5 glasses bring the most ideal results. Within the scope of radiation attenuation properties, each glass series was evaluated theoretically with Phy-X/PSD software, and LAC, HVL, and Zeff parameters were discussed in the photon energy range of 0.015 to 15 MeV. It was observed that LAC, HVL, and Zeff parameters decreased, increased, and decreased with increasing photon energy, respectively, while these three parameters improved with the addition of heavy oxide additions within the glass series. On the other hand, the experimental gamma ray spectroscopy test was applied to the ideal glass series, and their experimental radiation attenuation properties were determined. It was seen that the experimental results were in good agreement with the theoretical calculations, and the relative error margin varied between 0.59% and 2.91%. Experimental measurements at 662, 1173, and 1332 keV photon energy levels showed that the BT20Bi10-Ta5 sample was highly competitive with commercial radiation shielding glass materials in photon-shielding applications. On the other hand, in neutron attenuation applications, the BT20 sample showed extremely superior properties, revealing it to be a promising glass. As a result of all these, borotellurite-based glass formulations, which have unique and innovative glass compositions that can compete with their competitors and offer solutions for different radiation applications, have been developed to offer alternatives to the relevant application areas in a comprehensive and successful manner.