PHYSICOCHEMICAL AND ELECTROCHEMICAL PROPERTIES OF LN(SR)COO3 ELECTRODE MATERIALS

Continuous series of solid solutions with perovskite structure were found to be formed in systems Ln1-xSrxCoO3 where Ln = La or Gd. The thermal expansion coefficients of the rare-earth cobaltite solid solutions are between 14.10(-6) and 30.10(-6) K-1. It was found that the conductivities of Ln1-xSrCoO3 samples decrease reversibly with a decrease in oxygen partial pressure in the gas phase (from 10(5) to 10(-5) pa); this effect increases with increasing concentration of added strontium dopant. The oxygen transport numbers of La1-xSrCoO3 at 1100-1250 K are not over 0. 005; the ionic conductivities found at these temperatures are 0.3-1.0 S/cm. The polarization resistance of an La0.7Sr0.3CoO3 electrode on Bi0.75Y0.2501.5 solid electrolyte is lower than that of a silver electrode at the temperatures of 670 to 970 K and oxygen partial pressures of 1.9.10(5) to 0.21.10(5) Pa studied; that of a Nd0.5Sr0.5CoO3 electrode is lower than that of a silver electrode at high oxygen pressures. The dynamic characteristics of electrodes made of rare-earth cobaltites are superior to the corresponding characteristics of platinum electrodes.