Synthesis of delafossite CuAlO2 p-type semiconductor with a nanoparticle-based Cu(I) acetate-loaded boehmite precursor

Delafossite CuAlO2 p-type nanostructured semiconductor was synthesized using boehmite (γ-AlOOH) nanorods loaded with copper(I) acetate [Cu(OAc)] as a precursor (nanoprecursor). Because Cu(OAc)-loaded γ-AlOOH nanorods are highly anisotropic, they tend to form inherent bunches consisting of several nanorods during the course of drying the nanoprecursor dispersion droplet on a solid substrate. By annealing the nanoprecursor at 1150 °C in air, a delafossite CuAlO2 polycrystal was successfully obtained as the dominant phase. The CuAlO2 polycrystal is found to exhibit the (1 1 0) crystal orientation. The crystalline anisotropy of CuAlO2, which is not usually attainable using conventional molecular precursors, is presumably originated in the anisotropic morphology of the nanoprecursor. The Seebeck coefficient, resistivity and thermal conductivity of the CuAlO2 polycrystal at 300 K were found to be +560 μV K−1, 1.3 Ω m and 19.4 W K−1 m−1, respectively, confirming the p-type nature of the CuAlO2 polycrystal.