Germanium isotope effect induced guest rattling and cage distortion in clathrates

Ran Ang; Zhengshang Wang; Shang-Fei Wu; Pierre Richard; Zhenzhong Yang; Lin Gu; Gang Mu; Jingtao Xu; Ning Liu; Jun Tang

Journal of Materiomics (Dec 2018)

Germanium isotope effect induced guest rattling and cage distortion in clathrates

Ran Ang,
Zhengshang Wang,
Shang-Fei Wu,
Pierre Richard,
Zhenzhong Yang,
Lin Gu,
Gang Mu,
Jingtao Xu,
Ning Liu,
Jun Tang

Affiliations

Ran Ang: Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu, 610064, China; Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu, 610065, China
Zhengshang Wang: Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu, 610064, China
Shang-Fei Wu: Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
Pierre Richard: Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
Zhenzhong Yang: Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
Lin Gu: Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing, 100190, China; Corresponding author. Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Gang Mu: State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
Jingtao Xu: Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
Ning Liu: Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu, 610064, China
Jun Tang: Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu, 610064, China; Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu, 610065, China; Corresponding author. Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu, 610064, China.

Journal volume & issue: Vol. 4, no. 4
pp. 338 – 344

Abstract

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Intermetallic clathrates are materials characterized by a large cage structure where guest atoms can move anharmonically, providing these materials exotic thermoelectric properties. Unfortunately, the dynamical and atomic nature of the rattling phonons, and their interactions with the electronic structure, are not fully understood. Here, we report that a germanium isotope effect can trigger an inherent guest rattling and cage distortion in clathrate Ba8Ga16Ge30 (BGG). Raman-scattering spectroscopy and advanced electron microscopy demonstrate that the atomic germanium isotope effect induces an off-centre rattling at the 6d sites as well as a tetrakaidecahedron deformation which is anisotropic for n-type BGG but isotropic for p-type BGG. The present findings indicate that the large n-type germanium isotope effect arises from the strong electron-phonon coupling, which opens up a novel avenue for manipulating dynamical motions of phonons via atomic isotope engineering. Keywords: Thermoelectric, Clathrate, Isotope effect, Electron-phonon coupling

Published in Journal of Materiomics

ISSN: 2352-8478 (Print); 2352-8486 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials
Website: https://www.sciencedirect.com/journal/journal-of-materiomics

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