Oxides with pyrochlore structure are promising materials for SOFCs, oxygen and hydrogen separation membranes, and other devices. Ln zirconates attract interest due to their oxygen and protonic mobility. In this work, oxygen transport mechanism in Mg-doped Sm and Gd zirconates was studied. Sm_1.9Mg_0.1Zr₂O_6.95 and Gd_1.9Mg_0.1Zr₂O_6.95 oxides have been prepared via the mechanical activation and characterized by XRD, TGA, and SEM. Oxygen transport features were studied by the oxygen isotope exchange with C¹⁸O₂. Isotope substitution of bulk oxygen was demonstrated to be described by the 2D diffusion model. Very fast diffusion within grain boundaries provides fast isotope label distribution over the oxide domains, then tracer distributes due to a slower diffusion within domains’ bulk. Three forms of oxygen were distinguished within grains’ bulk. Very fast diffusion along grain boundaries (D_gb ~ 10⁻⁷ cm²/s at 700 °C) can provide high rates of oxygen transport in oxygen separation membranes.

中文翻译：

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镁在具有烧绿石结构的掺镁Sm和Gd锆酸盐中的扩散

具有烧绿石结构的氧化物是用于SOFC，氧气和氢气分离膜和其他设备的有前途的材料。锆酸锆由于其氧气和质子迁移率而引起人们的兴趣。在这项工作中，研究了Mg掺杂的Sm和Gd锆酸盐中的氧传输机理。通过机械活化制备了Sm _1.9 Mg _0.1 Zr ₂ O _6.95和Gd _1.9 Mg _0.1 Zr ₂ O _6.95氧化物，并通过XRD，TGA和SEM对其进行了表征。通过与C ¹⁸ O ₂的氧同位素交换研究了氧的传输特征。大量氧的同位素取代被证明由2D扩散模型描述。晶界内非常快的扩散提供了在氧化物域上的快速同位素标记分布，然后由于域内的散布速度较慢而导致示踪剂分布。谷物的主体中区分了三种形式的氧气。沿晶界非常快的扩散（d _GB  〜10 ^-7 厘米² / s的在700℃下）可以提供在氧气分离薄膜氧运输的高速率。