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The role of vacancies and local distortions in the design of new phase-change materials

The role of vacancies and local distortions in the design of new phase-change materials Phase-change materials are of tremendous technological importance ranging from optical data storage to electronic memories. Despite this interest, many fundamental properties of phase-change materials, such as the role of vacancies, remain poorly understood. ‘GeSbTe’-based phase-change materials contain vacancy concentrations around 10% in their metastable crystalline structure. By using density-functional theory, the origin of these vacancies has been clarified and we show that the most stable crystalline phases with rocksalt-like structures are characterized by large vacancy concentrations and local distortions. The ease by which vacancies are formed is explained by the need to annihilate energetically unfavourable antibonding Ge–Te and Sb–Te interactions in the highest occupied bands. Understanding how the interplay between vacancies and local distortions lowers the total energy helps to design novel phase-change materials as evidenced by new experimental data. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Materials Springer Journals

The role of vacancies and local distortions in the design of new phase-change materials

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References (56)

Publisher
Springer Journals
Copyright
Copyright © 2007 by Nature Publishing Group
Subject
Materials Science; Materials Science, general; Optical and Electronic Materials; Biomaterials; Nanotechnology; Condensed Matter Physics
ISSN
1476-1122
eISSN
1476-4660
DOI
10.1038/nmat1807
Publisher site
See Article on Publisher Site

Abstract

Phase-change materials are of tremendous technological importance ranging from optical data storage to electronic memories. Despite this interest, many fundamental properties of phase-change materials, such as the role of vacancies, remain poorly understood. ‘GeSbTe’-based phase-change materials contain vacancy concentrations around 10% in their metastable crystalline structure. By using density-functional theory, the origin of these vacancies has been clarified and we show that the most stable crystalline phases with rocksalt-like structures are characterized by large vacancy concentrations and local distortions. The ease by which vacancies are formed is explained by the need to annihilate energetically unfavourable antibonding Ge–Te and Sb–Te interactions in the highest occupied bands. Understanding how the interplay between vacancies and local distortions lowers the total energy helps to design novel phase-change materials as evidenced by new experimental data.

Journal

Nature MaterialsSpringer Journals

Published: Dec 17, 2006

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