Polyamorphism and origin of spatially heterogeneous dynamics in network-forming liquids under compression: Insight from visualization of molecular dynamics data

Abstract

Polyamorphism and dynamical heterogeneities in network-forming liquids (SiO2, GeO2, Al2O3) at 3200 K and in a wide pressure range are investigated by molecular dynamics simulation. Results show that their structure comprises three structural phases: TO 4-, TO5-, and TO6-phases (T Si, Ge, or Al). The size of structural phase regions significantly depends on compression. Besides, the mobility of atoms in different structural phases is different. For SiO 2 and GeO2 systems, the TO5-phase forms mobile regions. For Al2O3 system, AlO6-phase forms mobile regions. The coexistence of TOx-phases (x 4, 5, 6) in the network-forming liquids is origin of the spatially dynamical heterogeneity. © 2013 AIP Publishing LLC.