Journal article

Publication year: 2018

Pages: 113-122

Journal: ACS Applied Energy Materials

Volume number: 1

Issue number: 1

ISSN: 2574-0962

DOI Link: https://doi.org/10.1021/acsaem.7b00015

Publisher: American Chemical Society

Abstract: 
We present a combined microscopic and macroscopic study of YbxCo4Sb12 skutterudites for a range of nominal filling fractions, 0.15 < x < 0.75. The samples were synthesized using two different methods - a melt-quench-annealing route in evacuated quartz ampoules and a non-equilibrium ball-mill route - for which we directly compare the crystal structure and phase composition as well as the thermoelectric properties. Rietveld refinements of high-quality neutron powder diffraction data reveal about a 30-40% smaller Yb occupancy on the crystallographic 2a site than nominally expected for both synthesis routes. We observe a maximum filling fraction of at least 0.439(7) for a sample synthesized by the ball-mill routine, exceeding theoretical predictions of the filling fraction limit of 0.2-0.3. A single secondary phase of CoSb2 is observed in ball-mill-synthesized samples, while two secondary phases, CoSb2 and YbSb2, are detected for samples prepared by the ampoule route. A detrimental influence of the secondary phases on the thermoelectric properties is observed for secondary-phase fractions larger than 8 wt % regardless of the kind of secondary phase. The largest figure of merit of all samples with a ZT similar to 1.0 at 723 K is observed for the sample with a refined Yb content of x(2a) = 0.159(3), synthesized by the ampoule route.

Harvard Citation style: Ryll, B., Schmitz, A., de Boor, J., Franz, A., Whitfield, P., Reehuis, M., et al. (2018) Structure, Phase Composition, and Thermoelectric Properties of Yb_xCo₄Sb₁₂ and Their Dependence on Synthesis Method, ACS Applied Energy Materials, 1(1), pp. 113-122. https://doi.org/10.1021/acsaem.7b00015

APA Citation style: Ryll, B., Schmitz, A., de Boor, J., Franz, A., Whitfield, P., Reehuis, M., Hoser, A., Mueller, E., Habicht, K., & Fritscht, K. (2018). Structure, Phase Composition, and Thermoelectric Properties of Yb_xCo₄Sb₁₂ and Their Dependence on Synthesis Method. ACS Applied Energy Materials. 1(1), 113-122. https://doi.org/10.1021/acsaem.7b00015