Evaluation of radiation-induced amorphization of α-quartz in concrete aggregates using Raman spectroscopy

This study investigated the feasibility of Raman spectroscopy as a rapid and nondestructive chemical analysis tool for assessing radiation-induced amorphization in aggregate-forming minerals. Metachert and sandstone concrete aggregates, rich in quartz and containing additional minerals, such as albite and microcline in the case of sandstone, were exposed to various neutron fluence levels (1.2, 2.2, 7.0, and 14.3 × 10 19 n/cm², E ≥ 0.01 MeV) at ∼53.3°C. The Raman spectra of both the nonirradiated and irradiated samples were collected with a specific focus on quartz characterization. Concurrently, X-ray diffraction (XRD) refinement was employed to calculate the cell volume expansions of the studied mineral. The crystal lattice defects in α-quartz induced by neutron irradiation cause changes in the Raman band attributes (band position, full width at half maximum, and relative intensity), and are also responsible for the growth of defect bands. The behavior of the most intense vibrational bands can be used to estimate the change in the cell volume of irradiated α-quartz in different rocks. The data analysis presented in this study demonstrates a good correlation between the changes in the cell volume of quartz, as measured using XRD, and the Raman band attributes. This correlation enhances our understanding of structural alterations, emphasizing the potential of Raman spectroscopy as a reliable method for investigating the structural changes induced by the irradiation of minerals and highlighting its agreement with well-established XRD analyses.