Ideal band shape in the potential thermoelectric material CuAlO 2 : Comparison to Na x CoO 2

摘要: A potential thermoelectric material CuAlO${}_{2}$ is theoretically studied. We first construct a model Hamiltonian of based on the principles band calculation, and calculate Seebeck coefficient. Then, we compare with that well-known Na${}_{x}$CoO${}_{2}$, discuss similarities differences. It found two materials are similar from an electronic structure viewpoint in they have peculiar pudding-mold type shape, which advantageous for materials. There are, however, some differences, analyze origin difference microscopic viewpoint. The shape (a very flat top but overall wide bandwidth) to be even more ideal than predict once significant amount holes doped CuAlO${}_{2}$, properties (especially power factor) better those Na${}_{x}$CoO${}_{2}$ can expected.