Microstructure and high-temperature thermoelectric properties of polycrystalline CuAl1−xMgxO2 ceramics

We investigated the effect of Mg-substitution on the microstructure and high-temperature thermoelectric properties of CuAl1−xMgxO2 (0 ≤ x ≤ 0.2) fabricated by the tape casting method. The sintered CuAl1−xMgxO2 bodies crystallized in CuAl1−xMgxO2 solid solutions along with MgAl2O4 and Cu2MgO3 phases. Mg substitution up to x = 0.12 in the CuAl1−xMgxO2 yielded a higher electrical conductivity and lower Seebeck coefficient mainly because of an enhanced carrier density. The highest value of the power factor (3.47 × 10−5 W m−1 K−2) was attained for CuAl0.88Mg0.12O2 at 800 °C. It is demonstrated that Mg substitution is highly effective for improving high-temperature thermoelectric properties.