BaHf_0.8Ln_0.2O_3-δ doped with rare earth elements with different ionic radii (Ln = Yb, Y, Dy and Gd) as candidate materials for solid oxide fuel cells and H₂ separation membrane have been prepared. Their phase composition, sinterability, chemical stability and conductivity were studied systematically. The rare earth elements are successfully incorporated into the main phase crystal lattice of barium hafnate to generate a single perovskite phase. The relative density of all samples sintered at 1600 °C reaches above 90%, and Y-doped BaHfO₃ has the highest relative density (94.7%) and the biggest grain size (about 1 μm) among all samples. The conductivities of the samples firstly increase and then decrease with the increase of the doped ion radius. Among all samples the conductivity of BaHf_0.8Y_0.2O_3-δ is the highest and reaches 6.02 × 10⁻³ S cm⁻¹ in wet air at 700 °C, which is attributed to the good sinterability and suitable crystal structure (tolerance factor and free volume). All samples also show excellent chemical stability in the test atmospheres, including saturated H₂O steam, pure H₂ and CO₂, 200 ppm H₂S/Ar and boiling water. The Pt/BaHf_0.8Y_0.2O_3-δ electrolyte/Pt single cell was fabricated with a 530 μm-thick disk and its electrochemical properties were tested. The peak power density reaches 10.21 mW cm⁻² at 700 °C, which is comparable to similar fuel cells reported. These results suggest that BaHf_0.8Y_0.2O_3-δ is a promising electrolyte candidate for proton-conducting fuel cells.

BaHf _0.8 Ln _0.2 O _3-δ掺杂具有不同离子半径的稀土元素（Ln = Yb、Y、Dy和Gd）作为固体氧化物燃料电池和H ₂分离膜的候选材料已被制备。系统地研究了它们的相组成、烧结性、化学稳定性和电导率。稀土元素成功地结合到铪酸钡的主相晶格中以生成单一的钙钛矿相。所有样品在 1600 °C 下烧结的相对密度达到 90% 以上，Y 掺杂 BaHfO ₃在所有样品中具有最高的相对密度（94.7%）和最大的晶粒尺寸（约 1 μm）。样品的电导率随着掺杂离子半径的增大先增大后减小。在所有样品中，BaHf _0.8 Y _0.2 O _3-δ的电导率最高，在 700 °C 的湿空气中达到 6.02 × 10 ^-3  S cm ^-1，这归因于良好的烧结性和合适的晶体结构（容差因子和自由体积）。所有样品在测试环境中也表现出优异的化学稳定性，包括饱和 H ₂ O 蒸汽、纯 H ₂和 CO ₂、200 ppm H ₂S/Ar 和沸水。Pt/BaHf _0.8 Y _0.2 O _3-δ电解质/Pt 单电池用530 μm 厚的圆盘制造，并测试了其电化学性能。峰值功率密度在 700°C 时达到 10.21 mW cm ^-2，与报道的类似燃料电池相当。这些结果表明 BaHf _0.8 Y _0.2 O _3-δ是用于质子传导燃料电池的有前途的电解质候选者。