H/D isotope effects in the electrical conductivity of LaScO ₃ -based solid state proton-conducting electrolyte

Electrical conductivity of a solid proton-conducting electrolyte with the composition of La0.9Sr0.1ScO3 is studied depending on temperature and oxygen partial pressure in the atmospheres, humidified with H2O and D2O. Isotope H/D effect in the electrical conductivity is observed at the temperatures below 700 °C in air conditions. For reductive atmosphere, the isotope effect is pronounced for the whole investigated temperature range. Based on the pO2-dependencies of electrical conductivity, the transport numbers of ions and electron holes are determined. The ionic transport numbers in the H2O-containing atmosphere are found to be higher than the corresponding values for the D2O-containing atmosphere for all investigated conditions. The possible role of protons (deuterons) in the oxygen ion transport is pointed out. The kinetic isotope effect is found to be predominant in the conditions under study.