Structural and physico-mechanical investigations of Na₂B₄O7 geopolymer for γ-radiation attenuating applications

Abstract

The impact of borax additive on the gamma radiation attenuating property of Geopolymer (GP) systems is presented in this study. Comparative study of control GP and borax blended GP after gamma irradiation is carried out in a Sodium Iodide (NaI) gamma-ray spectrometer. The results indicate a significant increase in linear attenuation coefficient (μ) by 23.4%. The relationship of molecular structure of a material to its radiation attenuation property is crucial to understand for further improving radiation shielding abilities with negligible variation in density or mass of the material. Therefore, the microstructures of the two systems after irradiation were analysed using X-ray Diffractometer (XRD), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy (MAS-NMR) and Raman spectroscopy. Raman active modes confirms formation of higher order polymer networks in B1g internal mode of Si–O after addition of borax. Solid state 29Si MAS-NMR spectrum of borax blended GP system indicate an enhanced resonance in the Q3 and Q4 region implying the formation of Q3 sheets and Q4 framework, thus indicating the increase in reactivity and polymerisation process after addition of borax. Finally, correlations are drawn between the systems’ microstructural morphology and the corresponding radiation attenuating property.