“…[8,9] The surface-active impurities are absorbed in the prismatic face of the hexagonal graphite lattice, creating a non-faceted interface, that requires low driving forces to grow, i.e., low undercooling, like in the case of LGI, while for SGI the faceted interface requires larger undercooling to grow. [2,4,7] Previous experiments show that a completely impurities-free melt would solidify as SGI, indicating that the preferential shape for graphite is spheroids in the total absence of active surface impurities. [9] However, the amount of impurities needed to promote the formation of LGI is extremely low, [2] being the presence of O and S the most detrimental to that effect due to their strong tendency to reduce the surface energy.…”