PACS 61.43.Dq -Amorphous semiconductors, metals, and alloys PACS 62.50.-p -High-pressure effects in solids and liquids PACS 61.05.C--X-ray diffraction and scattering Abstract -Ge0.15Sb0.85 is a phase change material that undergoes a transition from a semiconducting glass to a crystalline metal when being densified. In this work, we investigate some parameters controlling the crystallization pressure Pc in related compounds by conducting highpressure experiments on initially amorphous, germanium-and silicon-doped antimony. We find that the amorphous phase is stabilized to higher pressures when the dopant size is decreased. This result can be easily rationalized under the assumption that in the glass, Ge and Si atoms occupy tetrahedral or related small coordination shells. When pressure increases, the larger Ge atoms move sooner into the larger octahedral shells, which are characteristic for the crystal, than the smaller Si atoms do. We also find that Pc increases quickly with Ge and Si concentrations. This observation implies that the pressure-induced change of coordination cannot be a local, elementary event, but that the four-coordination of the group-14 atoms is stabilized by the presence of other four-coordinated atoms.

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