TY - JOUR
T1 - Off-center guest vibrations and their effect on lattice thermal conductivity in n- and p-type β-Ba 8Ga 16Sn 30
AU - Suekuni, Koichiro
AU - Tanaka, Tomoo
AU - Yamamoto, Shuhei
AU - Avila, Marcos A.
AU - Umeo, Kazunori
AU - Takasu, Yuichi
AU - Hasegawa, Takumi
AU - Ogita, Norio
AU - Udagawa, Masayuki
AU - Takabatake, Toshiro
N1 - Funding Information:
Thermal conductivity and specific heat were measured at N-BARD, Hiroshima University. This work was financially supported by Grants in Aid for Scientific Research (A) (Grant No. 18204032), the priority area ™Nanospace® (Grant No. 19051011) and ™skutterudite® (Grant No. 15072205) from MEXT, Japan, and the Sasakawa Scientific Research Grant from the Japan Science Society.
Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2009/7
Y1 - 2009/7
N2 - We report on thermoelectric and Raman scattering studies of single crystalline samples of a type I clathrate Ba 8Ga 16Sn 30. The n- and p-type samples have a thermopower of -300 μV/K and +270 μV/K, and electrical resistivity of 20 mΩ cm and 40 mΩ cm at room temperature, respectively. Regardless of the charge carrier type, the lattice thermal conductivity κ L shows typical glass-like behavior. The low-energy vibration of Ba(2) in the tetrakaidecahedron is manifested in the Raman scattering spectrum as a peak at 15 cm -1. This energy agrees with the characteristic vibrational temperature of 20 K derived from the analysis of the specific heat data with a soft-potential model. The fact that both the vibrational energy and the magnitude of κ L for Ba 8Ga 16Sn 30 are lowest among the type I clathrates is evidence that off-center vibrations are responsible for the strong reduction of κ L. Analysis of κ L(T) revealed that the positional disorder associated with the off-center vibrations acts as the Rayleigh scattering center, and the coupling between guest vibrational modes and acoustic phonons is stronger than that in Sr 8Ga 16Ge 30 and Eu 8Ga 16Ge 30.
AB - We report on thermoelectric and Raman scattering studies of single crystalline samples of a type I clathrate Ba 8Ga 16Sn 30. The n- and p-type samples have a thermopower of -300 μV/K and +270 μV/K, and electrical resistivity of 20 mΩ cm and 40 mΩ cm at room temperature, respectively. Regardless of the charge carrier type, the lattice thermal conductivity κ L shows typical glass-like behavior. The low-energy vibration of Ba(2) in the tetrakaidecahedron is manifested in the Raman scattering spectrum as a peak at 15 cm -1. This energy agrees with the characteristic vibrational temperature of 20 K derived from the analysis of the specific heat data with a soft-potential model. The fact that both the vibrational energy and the magnitude of κ L for Ba 8Ga 16Sn 30 are lowest among the type I clathrates is evidence that off-center vibrations are responsible for the strong reduction of κ L. Analysis of κ L(T) revealed that the positional disorder associated with the off-center vibrations acts as the Rayleigh scattering center, and the coupling between guest vibrational modes and acoustic phonons is stronger than that in Sr 8Ga 16Ge 30 and Eu 8Ga 16Ge 30.
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U2 - 10.1007/s11664-009-0686-6
DO - 10.1007/s11664-009-0686-6
M3 - Article
AN - SCOPUS:67650489046
VL - 38
SP - 1516
EP - 1520
JO - Journal of Electronic Materials
JF - Journal of Electronic Materials
SN - 0361-5235
IS - 7
ER -