A maximum in the hardness of nanotwinned cadmium telluride

By varying the twin thickness from 4 to 23 nm, a maximum of hardness is achieved by molecular dynamics simulations at a twin thickness of 16 nm. When the twin thickness is >16 nm, the hardness is consistent with the Hall-Petch effect, whereas the hardness of a twin ⩽16 nm thick is in a good agreement with the reverse Hall-Petch effect. This is attributed to a transformation of the synergistic effect between both twin boundaries from monotonically increasing to decreasing with increasing twin thickness.