Oxygen permeation studies on La0.8Sr0.2Ga0.75Mg0.15Co0.10O3±δ

Abstract

Oxygen permeation measurements were carried out on La0.8Sr0.2Ga0.75Mg0.15Co0.10O3±δ specimens of different thickness at temperatures between 673 and 1173 K under various gradients of oxygen partial pressure. Simultaneously, the open circuit cell voltage was measured. It was shown that the investigated compositions were characterized by a high oxygen permeation rate, and, consequently, by a high electronic conductivity. The electrode polarization effect was experimentally proved, and the influence of the measurement conditions on the degree of the electrode polarization effect was studied and discussed in detail. In particular, this mentioned influence was found to be sufficiently smaller at higher oxygen partial pressures in the cathode (oxygen-rich) compartment, while the change of pO2 on the anode (oxygen-lean) side of the permeation cell did not lead to any sufficient electrode polarization. The values of the hole conductivity calculated from the experimental results found to be at least influenced by electrode polarization were used for calculations of the hole conductivity. The comparison of these values with results obtained by other experimental techniques (by pO2-dependence of the total conductivity measured using impedance spectroscopy and Hebb–Wagner-polarization technique) demonstrated a satisfactory agreement.