Thermoelectric properties of layered rare earth copper oxides

The series of layered rare earth copper oxides with RE2CuO4 type formula, where RE is neodymium, samarium, or gadolinium, has been prepared and various thermoelectric properties, viz. the electrical resistivity, Seebeck coefficient, and thermal conductivity, have been evaluated. The electrical resistivities of RE2CuO4 show negative temperature dependence and are extremely higher than those of the state-of-the-art thermoelectric materials. The Seebeck coefficients are negative in the whole temperature range, indicating that the majority of charge carriers are electrons. It was found that RE2CuO4 type oxides have relatively high thermal conductivities, which are about one order of magnitude higher than those of the state-of-the-art thermoelectric materials. The maximum value of the dimensionless figure of merit ZT is 0.0056 at about 950 K for SmCuO4. In order to utilize RE2CuO4 type oxides in an actual thermoelectric module, it is necessary to optimize the electrical properties and to reduce the thermal conductivity. (C) 2002 Elsevier Science B.V. All rights reserved.