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Calculating the thermal conductivity of the silicon clathrates using the quasi‐harmonic approximation
Author(s) -
Madsen Georg K. H.,
Katre Ankita,
Bera Chandan
Publication year - 2016
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201532615
Subject(s) - anharmonicity , thermal conductivity , phonon , silicon , diamond , condensed matter physics , thermal conduction , thermal , lattice (music) , materials science , clathrate hydrate , atom (system on chip) , harmonic , thermodynamics , chemistry , physics , hydrate , quantum mechanics , organic chemistry , computer science , composite material , embedded system , metallurgy , acoustics
A model of the lattice thermal conductivity, based on the quasi‐harmonic approximation, is validated on a dataset of 42 rock‐salt and zinc‐blende compounds. The model reliably reproduces experimental thermal conductivities ranging over several orders of magnitude. The good performance of the model is related to the definition of the mode‐averaged Grüneisen parameter. The model is applied to the silicon‐based clathrates and found to correctly reproduce the two orders of magnitude reduction of the lattice thermal conductivity compared to Silicon in the diamond structure. It is shown how the introduction of the clathrate structure and the guest atoms lead to a reduction of approximately one order of magnitude each. The clathrate structure is found to both increase the anharmonicity and decrease the average phonon velocity, whereas the reduction due to the guest atom is almost purely due to increased anharmonicity.