Interaction of O2, H2O and H2 with proton-conducting oxides based on lanthanum scandates

Abstract

An interaction of components from the gas phase, containing gaseous oxygen, hydrogen and water, with the La1–xSrxScO3–α oxides in the temperature range of 300–950 °С and partial pressure of 6.1–24.3 kPa 8.1–50.7 kPa has been studied using a high temperature thermogravimetric analysis. The effects of partial pressure of the gaseous oxygen, water and hydrogen on the apparent uptake level of protons with oxides has been found. The studies of incorporation processes of hydrogen from molecular hydrogen atmosphere into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates were performed in the temperature range of 300–800 °C and hydrogen pressure of 0.2 kPa by means of the isotope exchange method with the equilibration of isotope composition in the gas phase. The protons and deuterons concentrations were determined for the La0.91Sr0.09ScO3–α oxide. The existence of proton defects in the structure of studied oxides after the exposure in H2O and H2-containing atmospheres was revealed using the 1Н NMR. The role of oxygen vacancies in the proton incorporation processes is considered in the present work.