Synthesis and thermoelectric properties of Co1-xNixP3 and CoAs3-xPx skutterudites

Two types of promising phosphide skutterudite materials, Co_1-xNi_xP₃ (x= 0.025 to 0.70) and CoAs_3.xP_x(x=0.5 to 0. 10), have been synthesized and their thermoelectric properties measured. These compounds were prepared using a direct synthesis technique. The samples were hot pressed and analyzed by electron microprobe microscopy. Hall effect measurements were conducted to determine the electrical conductivity, mobility and carrier concentration. In addition, Seebeck coefficient and thermal conductivity measurements were performed. The thermoelectric properties are presented and discussed as a function of temperature up to 1273 K. The thermal stability of the primary CoP₃ was examined in a static vacuum under isothermal and in-gradient conditions. The effect of the presence of 1 atm of a cover gas on the material loss rate was analyzed.