Applicability of gas-phase isotope exchange method for investigation of porous materials.

Oxygen transport in ceramic oxide materials has been actively explored over the past decades. This is due to the desire to design high-temperature electrochemical devices for energy conversion. The research of oxygen transport is connected with necessity in understanding of processes proceeding between oxide materials and oxygen of gas phase. It is known that some functional parts of electrochemical devices have porous structure. Known methods for analyzing the kinetic interaction of oxygen in the gas phase and oxygen oxide, such as the use of 18O-labeled oxygen, are not always applicable for the study of porous materials. The paper shows the applicability of the isotope exchange method with the gas phase analysis to investigate porous ceramic materials using the La0.6Sr0.4MnO3–δ catalytic materials for oxygen reduction reaction. These measurements were taken in situ on materials with different porosity at temperature 800 °C and oxygen pressure 0.67 kPa. This paper shows the relationship between the intrinsic heterogeneous exchange rate (rH) and oxygen diffusion coefficient (D), and the effective apparent values obtained on the porous sample. [ABSTRACT FROM AUTHOR]