Journal Article

PreJuSER-19778

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Amorphous Ge_15Te_85: density functional, high-energy x-ray and neutron diffraction study

Kalikka, J. ; Akola, J. ; Jones, R. O.FZJ* ; Kohara, S. ; Usuki, T.

2012
IOP Publ. Bristol

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Please use a persistent id in citations: doi:10.1088/0953-8984/24/1/015802

Abstract: The structure and electronic properties of amorphous Ge(15)Te(85) have been studied by combining density functional (DF) simulations with high-energy x-ray and neutron diffraction measurements. Three models with 560 atoms have been constructed using reverse Monte Carlo methods constrained to (1) agree with the experimental structure factors S(Q), and have (2) energies close to the DF minimum and (3) a semiconducting band structure. The best structure is based on the melt-quenched DF structure and has a small number of Ge-Ge bonds. It shows interlocking networks of Te and GeTe with a significant fraction (22-24%) of voids (cavities). Ge occurs with both tetrahedral and 3 + 3 defective octahedral configurations, and the coordination of Te is slightly higher than indicated by the '8 - N rule' (N is the number of valence electrons). The GeTe network includes clusters of ABAB squares (A = Ge, B = Te), and the bonding is characterized by the chemical bond orders.

Keyword(s): J

Note: The calculations were performed on Jugene (IBM Blue Gene/P) and Juropa (Intel Xeon 5570) computers in the Forschungszentrum Julich with grants from the FZJ and the John von Neumann Institute for Computing (NIC). The synchrotron radiation experiment was approved by the Japan Synchrotron Radiation Research Institute (proposal No. 2006A1248). We thank the Academy of Finland and the Japan Science and Technology Agency for funding.

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Contributing Institute(s):

1. Quanten-Theorie der Materialien (PGI-1)

Research Program(s):

1. Grundlagen für zukünftige Informationstechnologien (P42)

Appears in the scientific report 2012

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Database coverage:
; Current Contents - Social and Behavioral Sciences ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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