Synthesis and high temperature thermoelectric properties of n-type Ba_yNi_xCo_4-xSb₁₂

Single-phase filled skutterudite compounds Ba_yNi_xCo_4-xSb₁₂ (x=0-0.1, y=0-0.4) were synthesized by a two-step solid state reaction. Effects of Ba filling fraction and Ni content on the thermoelectric properties of n-type Ba_yNi_xCo_4-xSb₁₂ were investigated. Thermal conductivity decreased with increasing Ba filling fraction and temperature. When barium filling fraction (y) was fixed at 0.3, thermal conductivity decreased with increasing Ni content, and reached a minimum value at about x=0.05. Electron concentration and electrical conductivity increased with increasing Ba filling fraction and Ni content. Seebeck coefficient increased with increasing temperature, and decreased with increasing Ba filling fraction and Ni content. A maximum ZT value of 1.2 was obtained at about 800 K for Ba_0.3Ni_0.05Co_3.95Sb₁₂.