Thermopower in the quadruple perovskite ruthenates

International audienceThe electrical resistivity and thermoelectric power of the paramagnetic ACu3Ru4O12 quadruple perovskite ruthenates with A=Na,Ca,Ca0.5La0.5, and La have been measured from T=5K up to 900 K, with the formal Ru oxidation state changing from 3.75(A=La3+) to 4.25(A=Na+). In this series of distorted metallic perovskites, resistivity curves present a metallic behavior, with no sign of saturation up to 900 K, typical of a bad metal. Two regimes are evidenced for the Seebeck coefficient S at high T, a quasilinear increase of S is observed up to 900 K, to a common value of ∼29-32μVK-1 at 900 K, while for T