The structural phase-transition pathway under compression and dynamic properties in liquid GeO2

Abstract

We perform a simulation of the structural phase-transition pathway under compression and dynamic properties in liquid germania (GeO2). The structure of liquid GeO2 is clarified through the pair radial distribution function (PRDF), distribution of GeO[Formula: see text] [Formula: see text] units, bond angle and length distribution, and three-dimensional (3D) visualization. The result shows that the structure of liquid GeO2 is built by GeO4, GeO5 and GeO[Formula: see text]units, which are linked to each other via common oxygen atoms. The GeO[Formula: see text] units lead to form into the separate GeO4-, GeO5- and GeO6-phases. The existence of separate phases is evidence of dynamical heterogeneity (DH) in liquid GeO2. The atoms in GeO5-phase are more mobile compared to other ones. The variation of the self-diffusions of Ge and O atoms under pressure is examined via the characteristics of separate GeO4-, GeO5- and GeO6-phases. We found that under compression, there is diffusion anomaly in liquid GeO2. This is suggested to be related to the very high mobility of Ge and O atoms in the GeO5-phase compared to GeO4- and GeO6-phase.