Electronic and vibrational properties of framework-substituted type-II silicon clathrates

2007 ◽  
Vol 75 (24) ◽  
Author(s):  
Koushik Biswas ◽  
Charles W. Myles
Keyword(s):  
Vibrational Properties ◽  
Type Ii ◽  
Silicon Clathrates

Efficient route to phase selective synthesis of type II silicon clathrates with low sodium occupancy

CrystEngComm ◽  
2014 ◽  
Vol 16 (19) ◽  
pp. 3940-3949 ◽  
Author(s):  
Lakshmi Krishna ◽  
Lauryn L. Baranowski ◽  
Aaron D. Martinez ◽  
Carolyn A. Koh ◽  
P. Craig Taylor ◽  
...  
Keyword(s):  
Selective Synthesis ◽  
Type Ii ◽  
Silicon Clathrates ◽  
Low Sodium ◽  
Efficient Route

Transport Properties of Type II Sodium-Silicon Clathrates

2005 ◽  
Vol 886 ◽  
Author(s):  
Matt Beekman ◽  
Jan Grkyo ◽  
George S. Nolas
Keyword(s):  
Thermal Conductivity ◽  
Sodium Content ◽  
Type I ◽  
Type Ii ◽  
Conductivity Measurements ◽  
Scanning Calorimetry ◽  
Resistivity Measurements ◽  
Silicon Clathrates ◽  
Covalently Bonded ◽  
First Time

ABSTRACTWe have synthesized the type II silicon clathrates Na1Si136 and Na8Si136, and report on the electrical and thermal transport in these materials. The crystal structure consists of a covalently bonded silicon framework in which sodium guest atoms are encapsulated inside the silicon host framework. Differential scanning calorimetry measurements show the compounds decompose above 600°C to diamond-structure silicon. Temperature dependant electrical resistivity measurements show the specimens to have an insulating character, with magnitudes that decrease with increasing sodium content. For the first time, thermal conductivity measurements on type II sodium-silicon clathrates are presented. The thermal conductivity is very low for both specimens, and for Na8Si136 exhibits a clear dip in the range from 50 to 70 K. These data suggest that the “rattling” behavior observed in type I clathrates may also be present in type II clathrates.

Dynamic free energy surfaces for sodium diffusion in type II silicon clathrates

2016 ◽  
Vol 18 (7) ◽  
pp. 5121-5128 ◽  
Author(s):  
J. G. Slingsby ◽  
N. A. Rorrer ◽  
L. Krishna ◽  
E. S. Toberer ◽  
C. A. Koh ◽  
...  
Keyword(s):  
Free Energy ◽  
Wide Band ◽  
Band Gaps ◽  
Type Ii ◽  
Silicon Clathrates ◽  
Photovoltaic Materials ◽  
Earth Abundant ◽  
Energy Surfaces ◽  
Sodium Diffusion

Earth abundant semiconducting type II Si clathrates have attracted attention as photovoltaic materials due to their wide band gaps.

scholarly journals Structural Origin of Reversible Li Insertion in Guest‐Free, Type II Silicon Clathrates

2021 ◽  
pp. 2000114
Author(s):  
Andrew Dopilka ◽  
J. Mark Weller ◽  
Alexander Ovchinnikov ◽  
Amanda Childs ◽  
Svilen Bobev ◽  
...  
Keyword(s):  
Type Ii ◽  
Silicon Clathrates

Molecular-dynamics studies on solid phase epitaxy of guest-free silicon clathrates

2001 ◽  
Vol 691 ◽  
Author(s):  
Shinji Munetoh ◽  
Koji Moriguchi ◽  
Teruaki Motooka ◽  
Kazuhito Kamei
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Structural Transition ◽  
Solid Phase ◽  
Experimental Studies ◽  
Md Simulations ◽  
Type I ◽  
Solid Phase Epitaxy ◽  
Type Ii ◽  
Silicon Clathrates

ABSTRACTDynamical phenomena during the solid phase epitaxy (SPE) of guest-free Si clathrates (Si34 and Si46) via molecular-dynamics (MD) simulations using the Tersoff potential have been reported. The activation energy of SPE for Si34 has been found to correspond with the experimental value for the cubic diamond phase (c-Si; approximately 2.7eV), while the SPE rates of Si46 are much lower than that of c-Si. The structural transition from Si46 (type-I) to Si34 (type-II) can be also observed during the Si46 [001] SPE. The present results suggest that it is worthwhile to intensify experimental studies concerning crystal growth techniques of clathrate materials and these interesting Si forms may open up a new field in “silicon technologies”.

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