A novel crystallographic location of rattling atoms in filled Eu
x
Co4Sb12 skutterudites prepared under high-pressure conditions
Author:
Rodrigues João Elias F. S.12ORCID, Gainza Javier1ORCID, Serrano-Sánchez Federico1ORCID, Nemes Norbert M.3ORCID, Dura Oscar J.4ORCID, Martínez Jose Luis1ORCID, Alonso Jose Antonio1ORCID
Affiliation:
1. Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC) , Sor Juana Inés de la Cruz 3, E-28049 , Madrid , Spain 2. European Synchrotron Radiation Facility (ESRF) , 71 Avenue des Martyrs, 38000 Grenoble , France 3. Departamento de Física de Materiales , Universidad Complutense de Madrid , E-28040 Madrid , Spain 4. Departamento de Física Aplicada , Universidad de Castilla-La Mancha , Ciudad Real , E-13071 , Spain
Abstract
Abstract
Thermoelectric M
x
Co4Sb12 skutterudites are well-known to exhibit a reduced thermal conductivity thanks to the rattling effect of the M-filler at the large cages occurring in the framework, centered at the 2a sites of the
I
m
3
‾
$Im\overline{3}$
space group. A novel Eu-filled skutterudite has been synthesized under high-pressure conditions at 3.5 GPa in a piston-cylinder hydrostatic press. The structural refinement from high-angular resolution synchrotron X-ray diffraction (SXRD) patterns unveils an unusual position for Eu filler atoms. By difference Fourier synthesis they are found at 12d sites, conforming statistically occupied octahedra within the mentioned cages around 2a positions. The Debye temperature was estimated by averaging the isotropic displacements by the atomic masses, leading to
θ
D
${\theta }_{D}$
of 273(2) K. Oftedal plots concerning the y and z Sb fractional positions, the unit-cell parameter
a
and M filling fraction include the novel Eu specimen in the trend observed for other filled materials prepared under high-pressure, including rare-earths, alkali or alkali-earth elements, all accepted as rattlers in filled skutterudites. A total thermal conductivity (κ) of 0.82 W m−1 K−1 is measured at 773 K for Eu0.02(1)Co4Sb12, below that of other filled skutterudites, which is promoted by the enhanced phonon scattering of Eu located at 12d sites. FE-SEM images showed large, homogeneous grains, well compacted after the high-pressure synthesis.
Publisher
Walter de Gruyter GmbH
Subject
Inorganic Chemistry,Condensed Matter Physics,General Materials Science
Reference33 articles.
1. Li, J.-F., Liu, W.-S., Zhao, L.-D., Zhou, M. High-performance nanostructured thermoelectric materials. NPG Asia Mater. 2010, 2, 152–158; https://doi.org/10.1038/asiamat.2010.138. 2. Snyder, G. J., Toberer, E. S. Complex thermoelectric materials. Nat. Mater. 2008, 7, 105–114; https://doi.org/10.1038/nmat2090. 3. Nolas, G. S., Morelli, D. T., Tritt, T. M. Skutterudites: a phonon-glass-electron crystal approach to advanced thermoelectric energy conversion applications. Annu. Rev. Mater. Sci. 1999, 29, 89–116. 4. Zhu, T., Liu, Y., Fu, C., Heremans, J. P., Snyder, J. G., Zhao, X. Compromise and synergy in high-efficiency thermoelectric materials. Adv. Mater. 2017, 29, 1605884; https://doi.org/10.1002/adma.201605884. 5. Slack, G. A. CRC handbook of hermoelectrics. In CRC Handbook of Thermoelectricshermoelectrics; Rowe, D. M., Ed.; CRC Press: Boca Raton, FL, 1995; pp. 407–440.
|
|