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Issue 31, 2018
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Structural disorder in the high-temperature cubic phase of GeTe

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Abstract

In traditional materials science, structural disorder tends to break the symmetry of the lattice. In this work, however, we studied a case which may be opposite to this intuition. The prototypical phase change material, GeTe, undergoes the phase transition from the rhombohedral structure to a more symmetric cubic one at ∼625 K. Using ab initio molecular dynamics simulations, we demonstrated that even in the cubic phase, the lattice is constructed by random short and long bonds, instead of bonds with a uniform length. Such bifurcation of the bond lengths enabled by Peierls-like distortion persists in the entire temperature range (0–900 K), yet with different degrees of disorder, e.g., the atoms are distorted along a certain direction in the rhombohedral phase (i.e., structural order) but the distortion varies stochastically in terms of direction and amplitude at high T (i.e., structural disorder). A more symmetric lattice frame coexisting with severe local structural disorder is the signature of this cubic GeTe. Our simulations have provided a theoretical support on the disordered Peierls-like distortion in the high-T cubic phase discovered earlier by X-ray experiments. By modulating the physical properties that different degrees of disorder may induce, we are able to design better functional materials for various applications in electronic and photonic devices.

Graphical abstract: Structural disorder in the high-temperature cubic phase of GeTe

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Article information


Submitted
24 Mar 2018
Accepted
07 May 2018
First published
11 May 2018

This article is Open Access

RSC Adv., 2018,8, 17435-17442
Article type
Paper

Structural disorder in the high-temperature cubic phase of GeTe

M. Xu, Z. Lei, J. Yuan, K. Xue, Y. Guo, S. Wang, X. Miao and R. Mazzarello, RSC Adv., 2018, 8, 17435
DOI: 10.1039/C8RA02561D

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