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Jawaher Mutlaq Al-Otaibi

Assistant Professor

Assistant Proffesor

كلية العلوم
B5, F3, R132

Three-phonon scattering processes and thermal conductivity in IV-chalocogenides

, Jawaher Al-Otaibi . 2015

We present a systematic study of allowed three-phonon scattering processes, involving acoustic and optical branches, and their relative roles in explaining the low thermal conductivity $\kappa $  of IV-chalcogenide thermoelectric materials PbTe, PbSe, PbS, and SnTe. Using numerical results for $\kappa $ , computed by employing the isotropic continuum scheme, we have examined the extent of the additional contribution the Callaway theory and the Allen theory provide over the single-mode relaxation time theory. Within the Callaway theory, for all these materials the acoustic ($\text{TA}$ $\text{LA}$ ) and transverse optical ($\text{TO}$ ) phonons contribute between 10–25% towards $\kappa $  at and above room temperature, with ${{\kappa}_{\text{TO}}}>{{\kappa}_{\text{TA}}}>{{\kappa}_{\text{LA}}}$ . The longitudinal optical ($\text{LO}$ ) phonons contribute negligibly (<5%) in Pb-chalogenides, but their contribution is larger (22%) than that of $\text{TO}$  phonons (18%) in SnTe. Due to the presence of high defect concentration in these materials, the high temperature conductivity varies less strongly than T−1. In confirmation with experimental measurements, our study finds that below the Debye temperature the resistivity of SnTe varies as the square-root of the point defect concentration.

Publication Work Type
PHD
Volume Number
27
Issue Number
33
Magazine \ Newspaper
Journal of Physics: Condensed Matter
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We present a systematic study of allowed three-phonon scattering processes, involving acoustic and optical branches, and their relative roles in explaining the low thermal conductivity …

by Jawaher Al-Otaibi , Srivastava GP
2015