Improvement in electrical properties of thermoelectric CuAlO ₂ ceramics aided by aluminosilicate glass

Abstract Delafossite CuAlO ₂ ( CAO ) ceramics were fabricated by the solid‐state route, using aluminosilicate glass powders as a sintering aid to improve the sintering ability and electrical conductivity, at 1473 K for 3 hours. The CAO ceramics with glass addition obviously enhanced bulk density, grain size, and electrical conductivity. It is found that the conductivity of CAO ceramics increased with the increase in glass content under 9.5%, whereas it was over 9.5%, the conductivity went down. The glass coming up to 9.5% increased the sintering ability and the electrical conductivity which was increased by one order of magnitude, thus increasing the figure of merit ZT for thermoelectric performance of our CAO added with 9.5% glass up to 9.82 × 10 ⁻³ at 773 K, which is a high value among the CAO ceramics. Besides, the impedance analysis shows that the impedance of the CAO ceramic was controlled by its grain boundary.