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-delta (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 h. 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-delta electrolyte. According to the results, the total conductivity of electrolyte CaZr1-xTmxO3-delta falls in 4.83 x 10-6 similar to 7.22 x 10-4 S cm-1 and the conductivity activation energy is 0.78 to 1.37 eV in oxygen and hydrogen atmosphere at 973 to 1173 degrees C. The chemical diffusion coefficient of proton in CaZr1-xTmxO3-delta proton conductor is between 5.9 x 10-7 and 4.5 x 10-6 cm2 s-1 in the temperature range of 973 to 1373 K and the diffusion activation energy is 55486 kJ mol-1. The interstitial proton concentration falls in 7.97 x 10-4 similar to 1.21 x 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. Electrolyte sample CaZr1-xTmxO3-delta (x = 0, 0.025, 0.05, 0.075, and 0.1) was successfully synthesized using high-temperature solid-phase method.We tested the conductivity of electrolyte CaZr1-xTmxO3-delta, the conductivity range is 4.83 x 10-6 to 7.22 x 10-4 S cm-1, and the conductivity activation energy is in the range of 0.78 to 1.37 eV.We tested the H/D isotope effect of electrolyte CaZr1-xYbxO3-delta, and obtained the chemical diffusion coefficient of hydrogen in electrolyte base on the H/D isotope effect, which falls in the range of 5.9 x 10-7 to 4.5 x 10-6 cm2 s-1.The interstitial proton concentration falls in 7.97 x 10-4 similar to 1.21 x 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.