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.