Radiation-induced defect formation and phase evolution in zirconium carbide ceramics

In this work, the evolution of defects in zirconium carbide (ZrC) nanocrystals under gamma irradiation was studied using both experimental and computational approaches. Positron Annihilation Spectroscopy (PAS) and Raman spectroscopy were used to characterize radiation-induced defects, structural changes, and vibrational modes in ZrC samples. Density Functional Theory (DFT) calculations revealed that the displacement damage in the ZrC lattice increased with irradiation dose, and the increase in defects led to a significant decrease in Young's modulus and to lower hardness. Irradiation at 3000 kGy enhances defect evolution by creating carbon vacancies that potentially combine with existing defects to form larger vacancy clusters. In the Raman spectra, a new peak due to Sp2 C-C was detected at 1795 cm⁻¹ at an absorption dose of 3000 kGy. The intensity ratio of the I_D/I_G band decreased from 1.133 (initial) to 1.09 (3000 kGy), reflecting amorphization and the formation of an oxide layer. These findings provide a foundation for future investigations aimed at optimizing the radiation tolerance of ZrC-based materials for advanced nuclear applications.