  We observe that pressure-induced amorphization of Ga2SeTe2 (a III-VI
semiconductor) is directly influenced by the periodicity of its intrinsic
defect structures. Specimens with periodic and semi-periodic two-dimensional
vacancy structures become amorphous around 10-11 GPa in contrast to those with
aperiodic structures, which amorphize around 7-8 GPa. The result is a notable
instance of altering material phase-change properties via rearrangement of
stoichiometric vacancies as opposed to adjusting their concentrations. Based on
our experimental findings, we posit that periodic two-dimensional vacancy
structures in Ga2SeTe2 provide an energetically preferred crystal lattice that
is less prone to collapse under applied pressure. This is corroborated through
first-principles electronic structure calculations, which demonstrate that the
energy stability of III-VI structures under hydrostatic pressure is highly
dependent on the configuration of intrinsic vacancies.
