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This paper gives a brief review of radiation damage caused by particle (ions and neutrons) bombardment in SiC at different temperatures, and its annealing, with an expanded discussion on the effects occurring on the surface. The surface effects were observed using SEM (scanning electron microscopy) with an in-lens detector and EBSD (electron backscatter diffraction). Two substrates were used, viz. single crystalline 6H-SiC wafers and polycrystalline SiC, where the majority of the crystallites were 3C-SiC. The surface modification of the SiC samples by 360 keV ion bombardment was studied at temperatures below (i.e. room temperature), just at (i.e. 350 °C), or above (i.e. 600 °C) the critical temperature for amorphization of SiC. For bombardment at a temperature at about the critical temperature an extra step, viz. post-bombardment annealing, was needed to ascertain the microstructure of bombarded layer. Another aspect investigated was the effect of annealing of samples with an ion bombardment-induced amorphous layer on a 6H-SiC substrate. SEM could detect that this layer started to crystalize at 900 °C. The resulting topography exhibited a dependence on the ion species. EBSD showed that the crystallites forming in the amorphized layer were 3C-SiC and not 6H-SiC as the substrate. The investigations also pointed out the behaviour of the epitaxial regrowth of the amorphous layer from the 6H-SiC interface. johan.malherbe@up.ac.za

Highlights • General solution to the Fick diffusion equation with an initially Gaussian profile. • Analyses the dominating property of this solution. • Compares approximate models/solutions to the exact solution.

Highlights• Glassy carbon samples were implanted with 200 keV Sr ions at room temperature to a fluence of 1 × 10 16 Sr + /cm 2 . The implanted samples were annealed in vacuum at temperature ranging from 23 °C-650 °C and in-situ real-time RBS analysis was carried out during the annealing process in order to investigate the diffusion behaviour of the implanted strontium.• The vacancy distribution profile derived from SRIM simulation shows that the radiation damage introduced by ion bombardment is concentrated towards the surface region of the glassy carbon substrate.• During low temperature annealing, the Sr atoms moved deeper into the bulk of the glassy carbon substrate due to the presence of vacancy and interstitial defects in the surface region of the glassy carbon. Migration of the implanted Sr towards the surface of the glassy carbon was observed at temperatures ranging from 560 °C-650 °C.• Migration of the implanted Sr towards the surface of the glassy carbon was observed at temperatures ranging from 560 °C-650 °C. The migration towards the surface was accompanied with segregation of Sr towards the surface. The segregated strontium was retained on the glassy carbon substrate and no loss of strontium was recorded.• The diffusion of Sr was limited to the damaged region of the glassy carbon and no diffusion into the pristine glassy carbon was observed. The results of the study show that glassy carbon is an excellent containment material for radioactive strontium. ABSTRACTThe diffusion behaviour of strontium in glassy carbon was investigated using in-situ real time

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