A molecular dynamics study on the liquid-amorphous-crystalline transition in a Lennard-Jonesian FCC system: II. Nanocrystalline plates

As a rapidly developing mass-data storage technology, phase change optical recording makes use of the difference in reflected light intensity between the amorphous and crystalline state of chalcogenide nanocrystalline plates. For a better understanding of the liquid-amorphous-crystalline transition behavior in such thin plates, a constant-pressure molecular dynamics simulation is performed for Lennard-Jonesian fee plates. The existence of the free surface leads the nanocrystalline plates to easy crystallization. Phase transition begins at a free surface and advances inward. Consequently, the critical quenching rate for amorphization displays a higher value for a nanocrystalline plate than for a bulk state. For a binary alloy, the critical quenching rate decreases with an increase in size misfit between solute and matrix atoms, with an increase in the solute concentration, and with an increase in the plate thickness. Crystallization on reheating from an amorphous phase initiates at a lower temperature for a nanocrystalline plate than that for a bulk state.