Mixed Conduction in A-Site Double-Perovskite Na1+xLa1-xZr2O6-δ Proton Conductors
Wenlong Huang1,2, Zheng Gao1,2, Ying Li1,2
1School of Metallurgy, Northeastern University, Shenyang 110819, China.
Abstract:
Perovskite-type proton conductors exist in two structural forms, ABO3 and A2B'B″O6. In this study, novel A-site double-perovskite proton conductors (A'A″B2O6) were proposed. Na1+xLa1-xZr2O6-δ (x = 0, 0.1, 0.2) perovskites were prepared by a solid-state reaction at 1200 °C. However, raising the sintering temperature to 1300 °C resulted in the Na to volatilize, converting the Na1.1La0.9Zr2O6-δ into La0.9Zr2O6-δ. The conductivities of these materials in a humid atmosphere were tested using electrochemical impedance spectroscopy, and their carrier transport numbers were measured using the defect equilibria model and concentration cell method. Na1.1La0.9Zr2O6-δ and Na1.2La0.8Zr2O6-δ are predominantly proton conductors, with Na1.1La0.9Zr2O6-δ exhibiting the highest proton transport number of 0.52 at 800 °C. In contrast, NaLaZr2O6 is predominantly an electronic conductor, while La0.9Zr2O6-δ functions as an oxide ion conductor. Due to their high protonic transport numbers, these Na1+xLa1-xZr2O6-δ A-site double-perovskite oxides present a promising avenue for the development of proton conductors.
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