Publication Date

10-30-2018

Department

Ames Laboratory; Physics and Astronomy

Campus Units

Ames Laboratory, Physics and Astronomy

OSTI ID+

1543566

Report Number

IS-J 9804

DOI

10.1016/j.jnoncrysol.2018.10.028

Journal Title

Journal of Non-Crystalline Solids

Volume Number

503-504

First Page

382

Last Page

388

Abstract

Phase-change material such as Ge2Sb2Te5 is usually utilized to store data due to the pronounced contrast in optical and electrical properties between crystalline and amorphous phases. As the density differs in the two phases, it is necessary to explore the influence of pressure on the structures of Ge2Sb2Te5, especially for the supercooled liquid which is an inevitable state in the formation of the two phases. The short-range structures in supercooled liquid Ge2Sb2Te5 under compression have been investigated by using ab initio molecular dynamics simulation. The supercooled liquid eventually changes to a solid with an increase in pressure. During the process, tetrahedrons decrease slightly, revealing that tetrahedral structures are insensitive to the pressure. Octahedrons increase as the pressure is less than 3.7 GPa and then decrease, suggesting that a moderate pressure can promote the formation of octahedrons. The body-centered-cubic, face-centered-cubic and hexagonal closed-packed structures are observed at 9.9 GPa and then increase gradually. Additionally, it is noticed that Sb- and Te-centered clusters prefer Ge-centered clusters to forming the high-coordinated short-range structures during the compression process. Our research make us aware of the effects of pressure on short-range structures in supercooled liquid, which is of great importance in the application of phase-change materials.

DOE Contract Number(s)

AC02-07CH11358

Language

en

Department of Energy Subject Categories

36 MATERIALS SCIENCE

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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