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Updated: May 7, 2026

Fabrication and Optimization of Type II Silicon Clathrate Films
Published on: October 14, 2025
Influence of guest loading on thermal properties of NaxSi136 clathrates
Andrew D Ritchie1, Michel B Johnson, John F Niven
1Department of Chemistry, Dalhousie University, Halifax, NS, B3H 4R2, Canada.
Abstract:
Thermal properties of a series of type II clathrates of the formula NaxSi136 with 0 < x < 24 and Na guests occupying the Si cages have been investigated over the temperature range from 2 to 300 K. Heat capacity and thermal conductivity results show that the structure is remarkably responsive to the loading of Na guests. The response is phononic: the host lattice expands in a non-monotonic way, and first stiffens, then relaxes at low loading into the larger Si28 cages (x < 9), then stiffens again as the Na concentration increases further. The response is also electronic, through changes in electronic properties as additional Na is loaded into the smaller Si20 cages at high loading (x > 9). In total, the influence of the guest loading illustrates the complexities of structure-property relations in a guest-host system.
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