Defect-induced topological order-to-disorder transitions in two-dimensional binary substitutional solid solutions: A molecular dynamics study

The crystal to glass transition is investigated in two-dimensional Lennard-Jones random binary substitutional solid solutions using constant temperature and pressure molecular dynamics simulation. We find that defects generated by atomic size disorder are mainly dislocations and dislocation complexes. They are responsible for crystalline phase instability. The nature of the transition is shown to be determined by defect properties such as formation energy and density, and by kinetic constraints. We observe a continuous transition from crystal to glass with an intermediate hexatic phase characterized by short-range translational order and quasi-long-range orientational order. The implication of these results for melting and solid state amorphization is discussed.