Thermally grown oxides (TGOs) at the ceramic top-coat/metallic bond-coat interface are a pressing challenge in advanced thermal barrier coating (TBC) systems as they can affect the performance and service lifetime of TBCs. Thus, developing novel TBC materials with ultralow oxygen ion diffusivity is very urgent. In this study, we reported the diffusive properties of oxygen ions in a novel pyrochlore-type La₂(Zr_0.7Ce_0.3)₂O₇ (LZ7C3) material. The measured ionic conductivity and atomistic simulation revealed that the oxygen ion diffusivity in LZ7C3 grains is two orders of magnitude lower than that in conventional 8 wt.% yttria-stabilized zirconia (8YSZ) grains. This is due to the relatively high energy barrier for oxygen hopping in LZ7C3. In addition, it was found that enhancing the order distribution of cations is a strategy to reduce the intrinsic oxygen diffusion of pyrochlore-type oxides. On the other hand, we observed that La³⁺ cations segregate at the grain boundaries (GBs) of LZ7C3, which results in the electrostatic potential at GBs being comparable to that in the bulk. Furthermore, we found that the oxygen ion diffusion is facilitated at the GBs of LZ7C3 due to the stretched O–Zr/Ce bond and the low coordination at GBs. However, the segregations of Y³⁺ cations and the increase in the number of oxygen vacancies resulted in the formation of an electrostatic layer at the GBs of 8YSZ, which shielded the oxygen ion diffusion. Despite this, the oxygen ion diffusivity in LZ7C3 was still considerably less than that in conventional 8YSZ. This study offers a stepping stone toward utilizing pyrochlore-type LZ7C3 materials as advanced TBCs at high temperatures.

陶瓷面涂层/金属粘合涂层界面处的热生长氧化物 (TGO) 是高级热障涂层 (TBC) 系统中的一项紧迫挑战，因为它们会影响 TBC 的性能和使用寿命。因此，开发具有超低氧离子扩散率的新型TBC材料迫在眉睫。在这项研究中，我们报告了氧离子在新型烧绿石型 La ₂ (Zr _0.7 Ce _0.3 ) ₂ O _{7 中}的扩散特性(LZ7C3) 材料。测量的离子电导率和原子模拟表明，LZ7C3 颗粒中的氧离子扩散率比传统的 8 wt.% 氧化钇稳定氧化锆 (8YSZ) 颗粒低两个数量级。这是由于 LZ7C3 中氧跳跃的能量势垒相对较高。此外，还发现增强阳离子的有序分布是减少烧绿石型氧化物固有氧扩散的一种策略。另一方面，我们观察到 La ³⁺阳离子在 LZ7C3 的晶界 (GBs) 处分离，这导致 GBs 的静电势与块体中的静电势相当。此外，我们发现由于拉伸的 O-Zr/Ce 键和 GBs 的低配位，LZ7C3 的 GBs 促进了氧离子扩散。然而，Y ³⁺阳离子的偏析和氧空位数量的增加导致在8YSZ的GBs处形成静电层，屏蔽了氧离子扩散。尽管如此，LZ7C3 中的氧离子扩散率仍远低于常规 8YSZ。这项研究为在高温下利用烧绿石型 LZ7C3 材料作为高级 TBC 提供了垫脚石。