Issue 24, 2017

Revealing the slow decomposition kinetics of type-I clathrate Ba8Ga16Ge30

Abstract

Inconsistencies in high temperature thermoelectric property measurements of Ba8Ga16Ge30 have prompted our study on the thermal stability of this heavily studied inorganic clathrate. Using X-ray diffraction, thermal analysis, and imaging techniques on both powder and spark plasma sintered pelletized samples, we probe the structure and decomposition characteristics of this important high temperature thermoelectric material. We demonstrate that the decomposition of Ba8Ga16Ge30 is extremely dependent on the heating conditions employed and, as a result of the slow decomposition kinetics of the clathrate, reveal that the true stability of this system has been overlooked in the extensive literature available. Loss of Ga and Ge from the clathrate cage is evident in all high temperature experiments under both air and inert environments. This study serves to highlight that the underlying structural chemistry and stability of thermoelectric materials at high temperature needs to be considered in parallel with the thermoelectric properties which constitute the figure of merit. Only then will reliable thermoelectric modules for real applications be realized.

Graphical abstract: Revealing the slow decomposition kinetics of type-I clathrate Ba8Ga16Ge30

Supplementary files

Article information

Article type
Paper
Submitted
19 Mar 2017
Accepted
21 May 2017
First published
25 May 2017

Phys. Chem. Chem. Phys., 2017,19, 15734-15744

Revealing the slow decomposition kinetics of type-I clathrate Ba8Ga16Ge30

H. Reardon, A. B. Blichfeld, H. Kasai, H. Yin, E. D. Bøjesen and B. B. Iversen, Phys. Chem. Chem. Phys., 2017, 19, 15734 DOI: 10.1039/C7CP01753G

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