Influence of Sintering Temperature on Electrical Properties of CuAlO₂ Ceramics

To improve the conductivity of CuAlO₂ ceramics, it is necessary to meet the requirements of thermoelectric devices. The delafossite CuAlO₂(CAO) ceramics was made of Cu₂O, Al₂O₃ and aluminosilicate glass powder with traditional solid sintering method. The influence of sintering temperature on the conductivity of CAO ceramics with aluminum silicate glass was studied. Results show that the density, grain size and electrical conductivity of CAO ceramics increase gradually with increasing sintering temperature. The apparent density and relative density of CAO ceramics reach maximum, 4.408 g/cm³ and 95.8%, respectively, when the sintering temperature is up to 1 175℃. When the sintering temperature comes up to 1 200℃, the grains of CAO ceramics develop fully and the shape of grains becomes polygon. The electrical conductivity reaches its maximum, 2.42 S/m, which increases by nearly 10 times as much compared with 1 050℃. The impedance spectrum analysis shows that with increasing sintering temperature, the improvement of the electrical conductivity of CAO ceramics is mainly due to the contribution of grain impedance.