Thermoelectric properties of Ni-doped CuAlO2

Abstract

Abstract The polycrystalline Ni-doped CuAlO 2 were obtained by solid state reaction method. The mixture of high purity grade of CuO, Al 2 O 3 and Ni(NO 3 ) 2 .6H 2 O 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 CuAl 1− x Ni x O 2 (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 CuAl 1− x Ni x O 2 solid solution phase along with the CuO and CuAl 2 O 4 phases were observed. From SEM micrographs, the grain size decreased from 6 to 2 μm when the amount of Ni in CuAl 1− x Ni x O 2 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 Ni 2+ ion in Cu + site of CuAl 1− x Ni x O 2 material may be drawn.