Effects of temperature and surface orientation on migration behaviors of helium atoms near titanium surfaces

The effects of temperature and surface orientation on migration behaviors of helium (He) atoms near titanium (Ti) surfaces have been investigated by molecular dynamics (MD) simulation. For the Ti (0 0 0 1) surface, He atoms can quickly escape out from the substrate and no trap mutation was observed near the surface at the temperature range of 500–1250 K. While for the Ti (0 1 $\overline{1}$ 0) and (2 $\overline{1}$ $\overline{1}$ 0) surfaces, trap mutations can occur within the neighboring region of the surfaces, which hinder the escape of He atoms. It is also found that the occurring probability of trap mutation near the surface depends on the temperature. The increasing temperature usually induces more trapped He atoms in the surface region. These results are useful for understanding the structural evolution and He thermal release on Ti surfaces.