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Description
This study examines the phase and structural evolution of Si3N4 ceramics subjected to irradiation with heavy Kr (147 MeV) and Xe (231 MeV) ions over the fluence range of 1010–1015 ions/cm2. At low irradiation doses, shifts in diffraction maxima and variations in the intensity of X-ray reflections, indicating the onset of polymorphic transformations between β-Si3N4 and α-Si3N4 [1], were observed. With increasing fluence up to 1013 ions/cm2, overlapping radiation-damaged regions, accompanied by swelling of the crystal lattice and a noticeable growth of the α-phase fraction, were formed. Raman spectroscopy revealed the progressive accumulation of irradiation-induced defects, manifested through the broadening and attenuation of vibrational modes, which are indicative of partial amorphization and the build-up of residual stresses. At fluences above 5×1013 ions/cm2, a complete amorphization of the near-surface region, as evidenced by the disappearance of characteristic diffraction peaks corresponding to both Si3N4 phases, was observed [2]. Overall, the results demonstrate that irradiation with energetic heavy ions provides a viable approach for tailoring the phase composition of Si3N4 ceramics. However, this process is inherently accompanied by radiation-induced degradation, including structural swelling, defect accumulation, and amorphization of the near-surface layer, which collectively lead to a deterioration in mechanical performance.
