Dynamical motions of a guest ion in type-I clathrate compounds have been studied by Raman scattering measurements. The anomalous temperature dependence of the guest phonon energy has been found not only for A8Ga 16Ge30(A=Ba, Sr, Eu), but also for A8Ga 16Si30-xGex(A = Ba, Sr). It has been found that the 4th order anharmonic potential is important to the guest ion motion. For Sr8Ga16Si30-xGex, the off-center rattling arises with the increase of Ge concentration, and it is confirmed that the off-center rattling plays an important role to the suppression of the lattice thermal conductivity.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)