Martensitic transformation of Cu on Ag(001) and Cu on Au(001) studied with classical molecular dynamics

摘要

The growth of Cu thin films on Ag(001) and Au(001) substrates was modeled using molecular dynamics with classical potentials. We observed that deposited atoms formed an unstable bcc or bcc/body-centered-tetragonal structure, in agreement with previous experiments. We show that the formation of such structures is related to film thickness and temperature that was analyzed in the interval from 200 to 600 K. bcc nucleation was measured by observing the relation between thickness and temperature of the deposited thin film. The martensitic transformation accompanied by a stripe pattern occurred as a consequence of the distortions caused by the underlying substrate lattice. The stripe patterns were measured as 57 and 61 A for Cu on Ag and Cu on Au, respectively. Monolayer spacing and coordination number of atoms were calculated, clearly evidencing the formed structures. Local structures were studied using the Ackland-Jones method, to determine the phases of the deposited films.