TY - JOUR
T1 - Phase-change materials
T2 - Vibrational softening upon crystallization and its impact on thermal properties
AU - Matsunaga, Toshiyuki
AU - Yamada, Noboru
AU - Kojima, Rie
AU - Shamoto, Shinichi
AU - Sato, Masugu
AU - Tanida, Hajime
AU - Uruga, Tomoya
AU - Kohara, Shinji
AU - Takata, Masaki
AU - Zalden, Peter
AU - Bruns, Gunnar
AU - Sergueev, Ilya
AU - Wille, Hans Christian
AU - Hermann, Raphaël Pierre
AU - Wuttig, Matthias
PY - 2011/6/21
Y1 - 2011/6/21
N2 - 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. Crystallization of amorphous solids is usually accompanied by significant changes of transport properties, such as an increase in thermal conductivity. Phase-change materials, however, reveal a remarkably low thermal conductivity in the crystalline state. This phenomenon is caused by the change of bonding upon crystallization which leads to an increase of the sound velocity and a softening of the optical modes.
AB - 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. Crystallization of amorphous solids is usually accompanied by significant changes of transport properties, such as an increase in thermal conductivity. Phase-change materials, however, reveal a remarkably low thermal conductivity in the crystalline state. This phenomenon is caused by the change of bonding upon crystallization which leads to an increase of the sound velocity and a softening of the optical modes.
KW - anharmonic lattice modes
KW - condensed matter
KW - gamma-ray spectroscopy
KW - phase-change materials
KW - phonon measurements
KW - thermal conduction
UR - http://www.scopus.com/inward/record.url?scp=79959524689&partnerID=8YFLogxK
U2 - 10.1002/adfm.201002274
DO - 10.1002/adfm.201002274
M3 - Article
AN - SCOPUS:79959524689
SN - 1616-301X
VL - 21
SP - 2232
EP - 2239
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 12
ER -