Structural Principles and Amorphouslike Thermal Conductivity of Na-Doped Si Clathrates

Abstract

The postulated low thermal conductivity and the possibility of altering the electronic conductivity of metal-doped clathrates with semiconducting host elements have stimulated great interest in exploring these compounds as promising thermoelectric materials. The electronic and thermal properties of the prototypical Na xSi (46) system are studied in detail here. It is shown that, despite the fact that the Na/Si clathrate is metallic, its thermal conductivity resembles that of an amorphous solid. A theoretical model is developed to rationalize the structural stability of the peculiar structural topology, and a general scheme for rational design of high efficiency thermoelectric materials is presented.

Thermal conductivity of Xe clathrate hydrate at low temperatures

“…9 The degree of anharmonicity and coupling depends strongly on the type of guest molecule. 8 The glasslike behavior of the thermal conductivity also was detected in some doped semiconductors [10][11][12] and organic 13,14 clathrates. In this study the thermal conductivity of Xe clathrate hydrate has been investigated and the origin of the noncrystal-line behavior of the thermal conductivity of crystal hydrates discussed.…”

Ab initiocomputational study on the lattice thermal conductivity of Zintl clathrates[Si19P4]Cl4andHärkönen1, Karttunen2 2016Phys. Rev. B11190View full textAdd to dashboardCite

“…The chosen q mesh (10,10,10) is a compromise between accuracy and computational requirements. For instance, for the clathrate framework Si 23 at 300 K, increasing the q mesh from (8,8,8) to (10,10,10) changes the lattice thermal conductivity by about 7.5%, whereas further increase from (10,10,10) to (11,11,11) changes the lattice thermal conductivity by about 1.4%. Both the lattice constants and the atomic positions of the studied structures were optimized by forcing the space group I43m.…”

Pressure-induced phase transformations in theBa8Si46clathrate

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Very low compressibility in a Na-doped Si clathrate with the type-II structure was first reported, 12 which transforms into an amorphous phase at ϳ12 GPa. In contrast, the type-I Si 46 clathrates of K ͑Ref.…”