Thermoelectric properties of Ni-doped CuAlO2

The polycrystalline Ni-doped CuAlO2 were obtained by solid state reaction method. The mixture of high purity grade of CuO, Al2O3 and Ni(NO3)2.6H2O powders was ground and then pressed by using uniaxial pressure. The obtained pellet was sintered in air at 1423 K for 24 h. XRD patterns showed the crystal structure of the as-sintered CuAl1−xNixO2 (0≤x≤0.10) belonging to rhombohedral, space group. No evidence of second phase was observed when Ni doping up to x=0.01. At Ni content x≥0.01 CuAl1−xNixO2 solid solution phase along with the CuO and CuAl2O4 phases were observed. From SEM micrographs, the grain size decreased from 6 to 2 μm when the amount of Ni in CuAl1−xNixO2 samples increased. Hall mobility and hole concentration of the as-sintered samples were obtained from Hall effect measurements at room temperature. The activation energy values deduced from the electrical resistivity measurements as a function of temperature were reported. The variation of Seebeck coefficient and power factor as a function of temperature was also investigated. From the experimental results, the substitution of Ni2+ ion in Cu+ site of CuAl1−xNixO2 material may be drawn.