2019年第66回応用物理学会春季学術講演会

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22 合同セッションM 「フォノンエンジニアリング」 » 22.1 合同セッションM 「フォノンエンジニアリング」

[10a-W371-1~12] 22.1 合同セッションM 「フォノンエンジニアリング」

2019年3月10日(日) 09:00 〜 12:15 W371 (W371)

塩見 淳一郎(東大)、馬場 寿夫(JST)

10:30 〜 10:45

[10a-W371-6] Anomalous Change of Heat Transfer in Sr(Ti,Nb)O3 solid solution

〇(D)Yuqiao Zhang1、Hai Jun Cho1,2、Masashi Mikami3、Sungmin Woo4、Myung-Chul Jung5、Woosuck Shin3、Woo Seok Choi4、Myung Joon Han5、Hiromichi Ohta1,2 (1.IST-Hokkaido Unv.、2.RIES-Hokkaido Unv.、3.AIST、4.Sungkyunkwan Univ.、5.KAIST)

キーワード:Thermal conductivity, Sr(Ti,Nb)O3, Solid solution

In this study, using SrTi1-xNbxO3 solid-solution (STNOss, 0.05 ≤ x ≤ 1) epitaxial films, we investigated heat transfer properties and observed anomalous behavior in the thermal conductivity. The lattice thermal conductivity (κlat) was extracted by κlat = κtotκele, where κtot is the total thermal conductivity measured by TDTR, and κele is electron thermal conductivity calculated with the Wiedmann-Franz law. Steep increases in both κtot and κlat were observed around x~0.5, suggesting a phase transition from SrTiO3-dominated phase to SrNbO3-dominated phase. This phase transition is also supported by polaron effect, which only exits in SrTiO3-dominated phase. Unlike the traditional alloy systems, SrNbO3, which has larger average atomic mass, shows much higher κlat than SrTiO3. According to the phonon dispersion calculations, SrTiO3 shows much more intense scattering between optical and acoustic branches than SrNbO3, which suppresses phonon mean free path for SrTiO3. The Grüneisen parameters of SrTiO3 were much higher than those of SrNbO3, which will reduce the phonon transport properties.Our findings of heat transports in STNOss will be a fundamental contribution to the current knowledge in heat transportation and may be utilized to develop new TE materials.