Application of La-0.9(Sr1-xCax)(1.1)CoO4 as a thermoelectric material

Electrical transport and magnetic properties of polycrystalline ceramic spe cimens of the system La-0.9(Sr1 - xCax) Co-1.1(4) have been investigated as a function of temperature by means of complex-plane impedance analysis whi ch distinguishes the bulk resistivity from the resistivity across grain bou ndaries, four-probe de resistivities, Seebeck coefficients and magnetic sus ceptibilities below room temperature. The temperature dependencies of the m agnetic susceptibilities indicate that the ratio of intermediate-spin Co-ii i ions (S = 1) is dominant in a specimen with x = 0.1. This suggests that L a-0.9(Sr1- xCax) 1.1CoO4 at x = 0.1 has a high potential as a thermoelectri c material. Therefore,it is necessary to search for thermoelectric material s in transition-metal perovskites using a spin-state control.