The
domain structural transition and structural heterogeneity (SH)
in GeO2 glass at 300 K and pressures up to 100 GPa are
studied by means of molecular dynamics (MD) simulation. The results
demonstrate that the structure of GeO2 glass comprises
domain D4, domain D5, or domain D6, which depends strongly on pressure,
where domain Dx (x = 4, 5, or 6)
is a cluster of connected GeO
x
units,
in which all Ge atoms possess the same coordination number of x. In the range of 9–18 GPa, GeO2 glass
undergoes a structural transformation from domain D4 to domain D6
via domain D5. Under densification, structural evolution occurs along
with the O
xx
→ O
xy
atom variation, which comprises the processes of both merging
and splitting of domain Dx and the exchange of domain-boundary
(DB) atoms. The densification leads to a decrease of the Voronoi polygon
(VP) volume of atoms. We found that the coexistence of separate domain
structures is the origin of spatial SH in GeO2 glass. Pressure-dependent
structural heterogeneity in GeO2 glass is also discussed
in detail.