Journal Article

PreJuSER-15486

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Phase-Change Materials: Vibrational Softening upon Crystallization and Its Impact on Thermal Properties

Matsunaga, T. ; Yamada, N. ; Kojima, R. ; Shamoto, S. ; Sato, M. ; Tanida, H. ; Uruga, T. ; Kohara, S. ; Takata, M. ; Zalden, P. ; Bruns, G. ; Sergueev, I. ; Wille, H. C. ; Hermann, R.FZJ* ; Wuttig, M.

2011
Wiley-VCH Weinheim

This record in other databases:  

Please use a persistent id in citations: doi:10.1002/adfm.201002274

Abstract: Crystallization of an amorphous solid is usually accompanied by a significant change of transport properties, such as an increase in thermal and electrical conductivity. This fact underlines the importance of crystalline order for the transport of charge and heat. Phase-change materials, however, reveal a remarkably low thermal conductivity in the crystalline state. The small change in this conductivity upon crystallization points to unique lattice properties. The present investigation reveals that the thermal properties of the amorphous and crystalline state of phase-change materials show remarkable differences such as higher thermal displacements and a more pronounced anharmonic behavior in the crystalline phase. These findings are related to the change of bonding upon crystallization, which leads to an increase of the sound velocity and a softening of the optical phonon modes at the same time.

Keyword(s): J

Note: Some synchrotron radiation experiments were performed on BL01B1 and BL02B2 at SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI). We express our sincere gratitude to Dr. K. Kato and Dr. K. Osaka at JASRI for their assistance with the experiment. We also express our sincere thanks to Mr. Katsumi Kawahara at Panasonic for his precise preparations of Ge-Sb-Te film samples. The structural model in Figure 4 of the Supporting Information was displayed using Java Structure Viewer (JSV 1.08 lite), created by Dr. Steffen Weber. Financial support by the Deutsche Forschungsgemeinschaft (Wu 243/17) and from the Helmholtz Gemeinschaft Deutscher Forschungszentren (RH Young Investigator Group) is gratefully acknowledged. We thank the European Synchrotron Radiation Facility for provision of nuclear inelastic-scattering beamtime at beamline ID22N and Mr. D. Bessas for his assistance during the experiment. A part of this work was supported by Core Research for Evolutional Science and Technology (CREST) "X-ray pinpoint structural measurement project: Development of the spatial-and time-resolved structural study for nano-materials and devices" and by the Academy of Finland and the Japan Science and Technology Agency through the Strategic Japanese-Finnish Cooperative Program on "Functional materials".

---

Contributing Institute(s):

1. Streumethoden (PGI-4)
2. Jülich-Aachen Research Alliance - Fundamentals of Future Information Technology (JARA-FIT)
3. Streumethoden (JCNS-2)

Research Program(s):

1. Grundlagen für zukünftige Informationstechnologien (P42)
2. Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) (P55)

Appears in the scientific report 2011

---