High temperature thermoelectric and optical properties of mixed haft B-trivalent CuFe0.5Al0.5O2 delafosite-oxides

Abstract

The mixing of a haft trivalent B-cation of CuFe0.5Al0.5O2 sample is investigated the enhancement of the thermoelectric and optical properties with comparing to the Cu-based delafossite of CuFeO2 and CuAlO2. The samples of CuFe0.5Al0.5O2, CuFeO2, and CuAlO2 delafossite were synthesized by solid state reaction at temperature 1050°C. The thermoelectric properties (Seebeck coefficient, electrical conductivity, and thermal conductivity) of all samples were measured in high temperature from 300 to 960K and the optical property was measured at room temperature. The result of Seebeck coefficient confirms that the mixing a haft trivalent CuFe0.5Al0.5O2 displays p-type conductor. The ZT value is not only higher than the Cu-based CuFeO2, and CuAlO2 samples, but also increase from 0.004 to 0.04 with the temperature range 300 to 960K. The indirect energy gap has energy 1.1eV which is lower than that energy of the undoped CuAlO2 and CuFeO2. In addition, the direct energy gap is in 3.5eV and has energy higher than 3.1eV under operation temperature approximate 950K as in the range of transparent visible light. These results confirm that the mixing of haft trivalent CuFe0.5Al0.5O2 enhances both thermoelectric and optical properties comparing with the Cu-based CuFeO2 and CuAlO2. Indeed, the p-type CuFe0.5Al0.5O2 compound displays high performance for both high temperature thermoelectric and transparent conducting oxide materials.