The Microstructure and Electrochemical Properties of Tm2O3-Doped CaZrO3

To understand the microstructure and electrochemical performance of Tm-doped CaZrO3-based proton conductor in more detail, CaZr1−xTmxO3−δ (x=0, 0.025, 0.05, 0.075 and 0.1) proton-conducting electrolyte samples were prepared by solid state reaction method at 1523 and 1873 K for 8 hours. The crystal structure of the proton-conducting solid electrolyte was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy. An electrochemical workstation was used to measure the electrical conductivity, the H/D isotope effect, and the chemical diffusion coefficient of hydrogen for the CaZr1−xTmxO3−δ electrolyte. According to the results, the total conductivity of electrolyte CaZr1-xTmxO3-δ falls in 4.83×10-6 ~ 7.22×10-4 S/cm and the conductivity activation energy is 0.78 to 1.37 eV in oxygen and hydrogen atmosphere at 973 to 1173℃. The chemical diffusion coefficient of proton in CaZr1-xTmxO3-δ proton conductor is between 5.9×10-7 and 4.5×10-6 cm2/s in the temperature range of 973 to 1373 K and the diffusion activation energy is 55486 kJ/mol. The interstitial proton concentration falls in 7.97×10-4~1.21×10-3 at 973 to 1073 K under hydrogen rich atmosphere. When the doping concentration (mol/mol) of Tm is 0.05, the electrolyte specimen has excellent electrochemical performance, the concentration of non-associated state Tm is approximately 2% of the total doping amount.