7-11 July 2014
Africa/Johannesburg timezone
<a href="http://events.saip.org.za/internalPage.py?pageId=16&confId=34"><font color=#0000ff>SAIP2014 Proceedings published on 17 April 2015</font></a>

Novel Rattling Dynamics Explain Low Thermal Conductivity in Aluminium-Doped Potassium Tungstate Defect Pyrochlore

10 Jul 2014, 14:00
20m
D Les 201

D Les 201

Oral Presentation Track A - Division for Physics of Condensed Matter and Materials DPCMM1

Speaker

Dr Elvis Shoko (University of the Witwatersrand)

Abstract content <br> &nbsp; (Max 300 words)<br><a href="http://events.saip.org.za/getFile.py/access?resId=0&materialId=0&confId=34" target="_blank">Formatting &<br>Special chars</a>

In a recent study, we reported an unusual quasielastic inelastic neutron scattering (INS) signal in the K analogue of the Al-doped series of cage compounds with the β-pyrochlore structure, AAl0.33W1.67O6 (A = K, Rb, Cs) [1]. We are studying this family of compounds because the rattling modes of the alkali metal atoms [2, 3] are similar to those found to enhance thermoelectric performance in both clathrates [4] and skutterudites [5]. This talk will discuss our recent thermal conductivity [6] and specific heat data in terms of the vibrational density of states calculated from ab initio molecular dynamics (MD) simulations validated against experimental INS spectra and show the significance of the novel K dynamics for these properties. I will conclude with a tentative sketch of the prospects of these compounds for thermoelectric development.

References
[1] E. Shoko, G. J. Kearley, V. K. Peterson, H. Mutka, M. M. Koza, J.-I. Yamaura, Z. Hiroi, G. J. Thorogood, submitted to Phys. Rev. B, ( arXiv:1310.8137).
[2] K. Oshiba and T. Hotta, J. Phys. Soc. Jpn. 80, 094712 (2011).
[3] J. Yamaura and Z. Hiroi, J. Phys. Soc. Jpn. 80, 054601 (2011), Z. Hiroi, J.-I. Yamaura and K. Hattori, J. Phys. Soc. Jpn. 81, 11012 (2012).
[4] B. C. Sales, B. C. Chakoumakos, R. Jin, J. R. Thompson and D. Mandrus, Phys. Rev. B 63, 245113
(2001).
[5] M. M. Koza, M. R. Johnson, R. Viennois, H. Mutka, L. Girard and D. Ravot, Nature Mater. 7, 805 (2008).
[6] E. Shoko, V. K. Peterson, and G. J. Kearley, J. Appl. Phys. 115, 033703, (arXiv:1310.8382v2)

Main supervisor (name and email)<br>and his / her institution

Prof. Daniel Joubert (daniel.joubert@wits.ac.za)

Apply to be<br> considered for a student <br> &nbsp; award (Yes / No)?

No

Level for award<br>&nbsp;(Hons, MSc, <br> &nbsp; PhD)?

No

Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?

No

Primary author

Dr Elvis Shoko (University of the Witwatersrand)

Co-authors

Prof. Gordon Kearley (Australian Nuclear Science and Technology Organisation) Dr Vanessa Peterson (Australian Nuclear Science and Technology Organisation)

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