Thermoelectric Properties of p-type Yb Filled Skutterudite Yb$_{y}$Fe$_{x}$Co$_{4-x}$Sb$_{12}$*

Since the discovery in 1995 of high thermoelectric figure of merit in skutterudite compounds, much work has been done to optimize the thermoelectric properties of these materials. As a result of this effort, n-type skutterudites are available today with figure of merit \textit{ZT} approaching 1.8. By contrast, p-type skutterudites have lagged behind, with the best materials having figure of merit less than unity. In this study, we report the thermoelectric and magnetic properties of p-type Yb-filled skutterudites of nominal composition Yb$_{y}$Fe$_{x}$Co$_{4-x}$Sb$_{12}$ with the aims of extending our knowledge of the filled skutterudite family and enhancing the thermoelectric properties of these p-type materials.