Single Crystal Structure Study of Type I Clathrate K_8Zn_4Sn_42 and K_8In_8Sn_38

Single crystals of type I clathrate K_8Zn_4Sn_42 and K_8In_8Sn_38 were grown by the flux method. The structure properties of both clathrates were investigated by single-crystal x-ray diffraction. Both clathrates crystallize in space group Pm3̅n , and no phase transition was observed in the investigated temperature range (100 K–450 K). The Debye temperature, the Einstein temperature, and the static disorder parameters of each clathrate were derived. The spread of the Einstein temperatures for K_8In_8Sn_38 , K_8Zn_4Sn_42 , and K_8In_8Sn_38 suggest that the charge distribution on the cage framework is crucial to the energy of rattling mode in the tetrakaidecahedron of the type-I clathrate.