High-pressure Raman study of the iodine-doped silicon clathrateI8Si44I2

Hiroyasu Shimizu, Tetsuji Kume, Toyoki Kuroda, Shigeo Sasaki, Hiroshi Fukuoka, Shoji Yamanaka
2003 Physical Review B (Condensed Matter)  
Raman scattering measurements of an iodine-doped I 8 Si 44 I 2 clathrate have been performed at pressures up to 28 GPa and 296 K. We found two Raman peaks at 75 and 101 cm Ϫ1 associated with the vibrations of guest I atoms inside the host Si cages, and observed some framework vibrations around 120-500 cm Ϫ1 . These characteristic Raman bands and their pressure dependence are investigated in consideration of our recent Ba 8 Si 46 studies. The lowest-frequency framework vibration at 133 cm Ϫ1
more » ... on at 133 cm Ϫ1 shows the softening with pressure, which seems to be the common feature of Si clathrates. A strong and broad Raman band centered at 461 cm Ϫ1 is identified to the highest-frequency framework vibration, which is likely intensified and broadened by the considerable framework distortion due to the replacement of framework Si with larger I atom. No obvious pressure-induced phase transition was found up to 28 GPa. The guest-host interactions are investigated by the present vibrational properties and are compared with those of previous neutron studies of I 8 Si 44 I 2 .
doi:10.1103/physrevb.68.212102 fatcat:j2l54aun4bc5djx47ejpaz2eay