Optical conductivity of rattling phonons in type-I clathrates Ba 8Ga16Ge30 and Ba8Ga 16Sn30

K. Iwamoto; T. Mori; S. Kushibiki; H. Honda; H. Matsumoto; K. Suekuni; M. A. Avila; T. Takabatake; N. Toyota

doi:10.4028/www.scientific.net/KEM.508.341

Optical conductivity of rattling phonons in type-I clathrates Ba ₈Ga₁₆Ge₃₀ and Ba₈Ga ₁₆Sn₃₀

K. Iwamoto, T. Mori, S. Kushibiki, H. Honda, H. Matsumoto, K. Suekuni, M. A. Avila, T. Takabatake, N. Toyota

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

1 Citation (Scopus)

Abstract

We review our dynamical property measurements of rattling phonons in type-I clathrate compounds, the quasi-on-center Ba₈Ga₁₆Ge ₃₀ (BGG) and off-center Ba₈Ga₁₆Sn₃₀ (BGS), using a terahertz time-domain spectrometer. The lowest-lying vibrational modes of rattling Ba ions in the oversized cage show anomalous temperature dependence in their spectra. For BGG, the temperature dependence is mostly consistent with a local anharmonic potential approximation that predicts softening towards low temperature. On the other hand, for BGS, a single broad peak of off-center rattling phonons splits into two subpeaks below 120 K, and, with further lowering temperature, the spectra show anomalous broadening. While the splitting can be understood by the double well potential, the linewidth broadening must be attributed to some relevant interactions with such excitations as acoustic phonons and doped carriers.

Original language	English
Title of host publication	Materials Integration
Publisher	Trans Tech Publications Ltd
Pages	341-346
Number of pages	6
ISBN (Print)	9783037853764
DOIs	https://doi.org/10.4028/www.scientific.net/KEM.508.341
Publication status	Published - 2012
Externally published	Yes
Event	Int. Symposium of GCOE: Materials Integration, in Conjunction with the 2nd Int. Symposium on Advanced Synthesis and Processing Technology for Materials, ASPT 2011 and the 8th Materials Science School for Young Scientists, KINKEN-WAKATE 2011 - Sendai, Japan Duration: Dec 1 2011 → Dec 2 2011

Publication series

Name	Key Engineering Materials
Volume	508
ISSN (Print)	1013-9826
ISSN (Electronic)	1662-9795

Other

Other	Int. Symposium of GCOE: Materials Integration, in Conjunction with the 2nd Int. Symposium on Advanced Synthesis and Processing Technology for Materials, ASPT 2011 and the 8th Materials Science School for Young Scientists, KINKEN-WAKATE 2011
Country/Territory	Japan
City	Sendai
Period	12/1/11 → 12/2/11

All Science Journal Classification (ASJC) codes

Materials Science(all)
Mechanics of Materials
Mechanical Engineering

Access to Document

10.4028/www.scientific.net/KEM.508.341

Cite this

Iwamoto, K., Mori, T., Kushibiki, S., Honda, H., Matsumoto, H., Suekuni, K., Avila, M. A., Takabatake, T., & Toyota, N. (2012). Optical conductivity of rattling phonons in type-I clathrates Ba ₈Ga₁₆Ge₃₀ and Ba₈Ga ₁₆Sn₃₀. In Materials Integration (pp. 341-346). (Key Engineering Materials; Vol. 508). Trans Tech Publications Ltd. https://doi.org/10.4028/www.scientific.net/KEM.508.341

Iwamoto, K, Mori, T, Kushibiki, S, Honda, H, Matsumoto, H, Suekuni, K, Avila, MA, Takabatake, T & Toyota, N 2012, Optical conductivity of rattling phonons in type-I clathrates Ba ₈Ga₁₆Ge₃₀ and Ba₈Ga ₁₆Sn₃₀. in Materials Integration. Key Engineering Materials, vol. 508, Trans Tech Publications Ltd, pp. 341-346, Int. Symposium of GCOE: Materials Integration, in Conjunction with the 2nd Int. Symposium on Advanced Synthesis and Processing Technology for Materials, ASPT 2011 and the 8th Materials Science School for Young Scientists, KINKEN-WAKATE 2011, Sendai, Japan, 12/1/11. https://doi.org/10.4028/www.scientific.net/KEM.508.341

@inproceedings{1a83a9b90fc24d4db8924c9b30cf8c3c,

title = "Optical conductivity of rattling phonons in type-I clathrates Ba 8Ga16Ge30 and Ba8Ga 16Sn30",

abstract = "We review our dynamical property measurements of rattling phonons in type-I clathrate compounds, the quasi-on-center Ba8Ga16Ge 30 (BGG) and off-center Ba8Ga16Sn30 (BGS), using a terahertz time-domain spectrometer. The lowest-lying vibrational modes of rattling Ba ions in the oversized cage show anomalous temperature dependence in their spectra. For BGG, the temperature dependence is mostly consistent with a local anharmonic potential approximation that predicts softening towards low temperature. On the other hand, for BGS, a single broad peak of off-center rattling phonons splits into two subpeaks below 120 K, and, with further lowering temperature, the spectra show anomalous broadening. While the splitting can be understood by the double well potential, the linewidth broadening must be attributed to some relevant interactions with such excitations as acoustic phonons and doped carriers.",

author = "K. Iwamoto and T. Mori and S. Kushibiki and H. Honda and H. Matsumoto and K. Suekuni and Avila, {M. A.} and T. Takabatake and N. Toyota",

year = "2012",

doi = "10.4028/www.scientific.net/KEM.508.341",

language = "English",

isbn = "9783037853764",

series = "Key Engineering Materials",

publisher = "Trans Tech Publications Ltd",

pages = "341--346",

booktitle = "Materials Integration",

note = "Int. Symposium of GCOE: Materials Integration, in Conjunction with the 2nd Int. Symposium on Advanced Synthesis and Processing Technology for Materials, ASPT 2011 and the 8th Materials Science School for Young Scientists, KINKEN-WAKATE 2011 ; Conference date: 01-12-2011 Through 02-12-2011",

}

TY - GEN

T1 - Optical conductivity of rattling phonons in type-I clathrates Ba 8Ga16Ge30 and Ba8Ga 16Sn30

AU - Iwamoto, K.

AU - Mori, T.

AU - Kushibiki, S.

AU - Honda, H.

AU - Matsumoto, H.

AU - Suekuni, K.

AU - Avila, M. A.

AU - Takabatake, T.

AU - Toyota, N.

PY - 2012

Y1 - 2012

N2 - We review our dynamical property measurements of rattling phonons in type-I clathrate compounds, the quasi-on-center Ba8Ga16Ge 30 (BGG) and off-center Ba8Ga16Sn30 (BGS), using a terahertz time-domain spectrometer. The lowest-lying vibrational modes of rattling Ba ions in the oversized cage show anomalous temperature dependence in their spectra. For BGG, the temperature dependence is mostly consistent with a local anharmonic potential approximation that predicts softening towards low temperature. On the other hand, for BGS, a single broad peak of off-center rattling phonons splits into two subpeaks below 120 K, and, with further lowering temperature, the spectra show anomalous broadening. While the splitting can be understood by the double well potential, the linewidth broadening must be attributed to some relevant interactions with such excitations as acoustic phonons and doped carriers.

AB - We review our dynamical property measurements of rattling phonons in type-I clathrate compounds, the quasi-on-center Ba8Ga16Ge 30 (BGG) and off-center Ba8Ga16Sn30 (BGS), using a terahertz time-domain spectrometer. The lowest-lying vibrational modes of rattling Ba ions in the oversized cage show anomalous temperature dependence in their spectra. For BGG, the temperature dependence is mostly consistent with a local anharmonic potential approximation that predicts softening towards low temperature. On the other hand, for BGS, a single broad peak of off-center rattling phonons splits into two subpeaks below 120 K, and, with further lowering temperature, the spectra show anomalous broadening. While the splitting can be understood by the double well potential, the linewidth broadening must be attributed to some relevant interactions with such excitations as acoustic phonons and doped carriers.

UR - http://www.scopus.com/inward/record.url?scp=84859710794&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84859710794&partnerID=8YFLogxK

U2 - 10.4028/www.scientific.net/KEM.508.341

DO - 10.4028/www.scientific.net/KEM.508.341

M3 - Conference contribution

AN - SCOPUS:84859710794

SN - 9783037853764

T3 - Key Engineering Materials

SP - 341

EP - 346

BT - Materials Integration

PB - Trans Tech Publications Ltd

T2 - Int. Symposium of GCOE: Materials Integration, in Conjunction with the 2nd Int. Symposium on Advanced Synthesis and Processing Technology for Materials, ASPT 2011 and the 8th Materials Science School for Young Scientists, KINKEN-WAKATE 2011

Y2 - 1 December 2011 through 2 December 2011

ER -