Framework contraction in Na-stuffed Si(cF136).
Systematic crystal structure refinements from powder X-ray diffraction data as well as density functional theory calculations demonstrate that the silicon clathrate II Si(cF136) exhibits a lattice contraction as Na is introduced solely into the Si(28) cages. When the Si(20) cages, in addition, begin to be filled with Na, a contrasting lattice expansion results. The nonmonotonic structural response to filling is an indication of markedly dissimilar guest-framework interactions for Na@Si(20) and Na@Si(28).
Beekman
Matt
M
Department of Physics, University of South Florida, Tampa, Florida 33620, USA.
Nenghabi
Emmanuel N
EN
Biswas
Koushik
K
Myles
Charles W
CW
Baitinger
Michael
M
Grin
Yuri
Y
Nolas
George S
GS