Synthesis and thermoelectric properties of p-type Ba8Ga16ZnxGe30－x clathrates

Abstract

Ba8Ga16ZnxGe30-x(x=3, 4, 5, 6) clathrates with different Zn contente were synthesized by melt method reaction and spark plasma sintering. The effect of Zn composition on the thermoelectric properties were investigated. The results show that all samples behave p-type conductor. The electric conductivity and room-temperature carrier mobility decrease with increasing Zn content, and the room-temperature carrier density Np increases with increasing Zn content. Of all p-type Ba8Ga16ZnxGe30-x compounds, Ba8Ga16Zn3Ge27 has the highest Seebeck coefficient, the value of which is 234 μV·K-1 at 300 K, and reaches as high as 295 μV·K-1 around 700 K. The thermal conductivity of Ba8Ga16ZnxGe30-x decrease with increasing x. The maximum ZT value of 0.38 is obtained at 806 K for Ba8Ga16Zn3Ge27.