Low temperature transport properties of the BiCuSeO system

The discovery of a 26 K superconductivity in the tetragonal iron-based pnictide LaFeAsO_{1 - x}F_x (x = 0.05-0.12) has stimulated a tremendous search for superconductivity in a wide class of materials with similar structure. Beside superconductivity, promising thermoelectric properties have been discovered in this family in the cryogenic temperature range and in the p-type BiCuSeO system around 400-600°C. In this paper, we report on the effect of various substitutions on the low temperature properties of this system. Whatever the substitution, all samples revealed p-type, and no superconductivity was observed. Moreover, although some of these compounds exhibit very promising thermoelectric properties above room temperature, this is not the case in the low temperature range.