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Please indicate whether<br>this abstract may be<br>published online<br>(Yes / No)
Yes
Level for award<br> (Hons, MSc, <br> PhD, N/A)?
PhD
Apply to be<br> considered for a student <br> award (Yes / No)?
Yes
Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?
Yes
Abstract content <br> (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>
A low thermal conductivity material is a good choice for a thermoelement provided the power factor is not affected adversely. In this study, the suppression of thermal conductivity, using the high temperature phase in the three binary type-I Sn clathrates, Cs8Sn44, K8Sn44 and Rb8Sn44 was studied using Density Functional Theory in the Local Density
approximation. Analysis of the projected density of state suggests a decoupled oscillations of the guest atoms which is believed to scatter the acoustic phonons and hence reduce the lattice thermal conductivity [1]. Using ab initio molecular dynamics phonon calculations, an indication of any anharmonicity was investigated. Our result is confirmed by a detailed analysis of the lattice vibrations and the role the guest atoms play in reducing the lattice thermal conductivity from similar studies using Raman spectroscopy and inelastic neutron scattering [2].
[1] Voneshen, D. J., Refson, K., Borissenko, E., Krisch, M., Bosak, A., Piovano, A., ... & Roger, M. (2013). Suppression of thermal conductivity by rattling modes in thermoelectric sodium cobaltate. Nature materials, 12(11), 1028-1032.
2] Christensen, Mogens, Fanni Juranyi, and Bo B. Iversen. "The rattler effect in thermoelectric clathrates studied by inelastic neutron scattering." Physica B: Condensed Matter 385 (2006): 505-507.
Main supervisor (name and email)<br>and his / her institution
Prof. Daniel P Joubert [daniel.joubert2@wits.ac.za ]
University Of Witwatersrand, Johannesburg
