Gallium distribution in the clathrates Sr[sub 8]Ga[sub 16]Ge[sub 30] and Sr[sub 4]Eu[sub 4]Ga[sub 16]Ge[sub 30] by resonant diffraction

Zhang, Yuegang; Lee, Peter L.; Nolas, George. S.; Wilkinson, Angus P.
April 2002
Applied Physics Letters;4/22/2002, Vol. 80 Issue 16, p2931
Academic Journal
The distribution of gallium/germanium in the type-I clathrates Sr[sub 8]Ga[sub 16]Ge[sub 30] and Sr[sub 4]Eu[sub 4]Ga[sub 16]Ge[sub 30] over the three crystallographically distinct framework sites has been determined by resonant diffraction. The analyses indicate a strong preference for the occupation of the 6c site by gallium. This is consistent with theoretical predictions, but contrary to the results of a previous neutron diffraction study. The gallium distribution, and, hence, the thermoelectric properties of these materials, may be amenable to manipulation by heat treatment. © 2002 American Institute of Physics.


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