Fig. 1. Schematic diagram of sample irradiation and cross-sectional micro-Raman spectroscopy(a) The micro-Raman device, (b) Two-dimensional Raman spectroscopy physics and pixel size (color online)

Fig. 2. Energy loss of 30 MeV ⁵⁸Ni⁵⁺ and ¹⁰⁷Ag⁵⁺ ions in graphite carbon (ICRU-906) target calculated by using the all-cascade damage model, the vacancies and ion distributions generated by the two types of ions(a) Electron energy loss, (b) Nuclear energy loss, (c) Total energy loss, (d) ⁵⁸Ni⁵⁺, (e) ¹⁰⁷Ag⁵⁺

Fig. 3. Normalized Raman spectra of nuclear graphite irradiated by ¹⁰⁷Ag⁵⁺ ions as a function of different depths: the line scan graph (a) and typical Raman spectra at different depths (c) under dose of 0.3×10¹⁶ ions∙cm^-2; the line scan graph (b) and typical Raman spectra at different depths (d) under dose of 0.9×10¹⁶ ions∙cm^-2 (color online)

Fig. 4. Schematic diagram of the Raman spectra fitting for nuclear graphite (color online)(a) Pristine nuclear graphite, (b) Irradiated nuclear graphite

Fig. 5. Grayscale map of different Raman parameters for the D peak and G peak under different doses of 0.3×10¹⁶ ions∙cm^-2 (a~h) and 0.9×10¹⁶ ions∙cm^-2 (a1~h1): (a, a1) D Position, (b, b1) D area, (c, c1) FWHM(D), (d, d1) D height, (e, e1) G position, (f, f1) G area, (g, g1) FWHM(G), (h, h1) G height

Fig. 6. Comparison of I_D/I_G at different depths of nuclear graphite irradiated by ¹⁰⁷Ag⁵⁺ ions with different fluences: the grayscale map (a) and scatter plots (c) under dose of 0.3×10¹⁶ ions∙cm^-2; the grayscale map (b) and scatter plots (d) under dose of 0.9×10¹⁶ ions∙cm^-2

Fig. 7. Variation of the G peak position of nuclear graphite and comparison of Raman spectra between heavily irradiated regions and unirradiated regions under irradiation fluence of 0.3×10¹⁶ ions∙cm^-2 (a) and 0.9×10¹⁶ ions∙cm^-2 (b); Standard error plots of G peak at different depths under irradiation fluence of 0.3×10¹⁶ ions∙cm^-2 (c) and 0.9×10¹⁶ ions∙cm^-2 (d)

Fig. 8. Scatter plot showing the variation of Raman spectral characteristic parameters of IG-110 irradiated with ¹⁰⁷Ag⁵⁺ and ⁵⁸Ni^5+[23] ions as a function of DPA (a) I_D/I_G , (b) FWHM(G)

Fig. 9. I_D/I_Gvs. FWHM(G) for irradiated regions (solid symbols) and unirradiated regions (hollow symbols) under different ion irradiations (color online)

Table 1. Nominal physical and mechanical properties of IG-110

Table 2. Ion irradiation parameters of nuclear graphitic materials

Table 3. Comparison of fitting results for ¹⁰⁷Ag⁵⁺ and ⁵⁸Ni^5+[23]