Abstract The poor fracture toughness of cubic pyrochlores has severely blocked their wide application. To toughen them, a series of yttrium dopants have been introduced to lanthanum zirconate, creating atomic or phase-scale compressive stress dependent on the concentration of dopants. We find bigger substitutional dopants, rather than smaller ones, can toughen cubic ceramics, attributing to the dominance of an imposed atomic compressive stress to surroundings over the local one near normal point defects. For special point defects such as oxygen vacancies or interstitials, the local stress in their vicinity could become dominant given an adequate concentration. Despite of the pyrochlore/fluorite intermixture possessing evidently reduced grains, it only exhibits intermediate fracture toughness, suggesting negligible grain refining effects on toughening. Further, a random distribution of atomic compressive stress induced by disordered oxygen vacancies is beneficial to toughening. This research highlights the atomic compressive stress on toughening, providing guidance for future design of novel thermal barrier coatings.

中文翻译：

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掺钇锆酸镧固溶体中原子和相尺度压应力对断裂韧性的影响

摘要 立方烧绿石断裂韧性差，严重阻碍了其广泛应用。为了强化它们，一系列钇掺杂剂被引入到锆酸镧中，根据掺杂剂的浓度产生原子或相级压缩应力。我们发现较大的替代掺杂剂而不是较小的替代掺杂剂可以增强立方陶瓷，这归因于对周围环境施加的原子压应力在接近正常点缺陷的局部区域上占主导地位。对于特殊的点缺陷，例如氧空位或间隙，如果浓度足够，它们附近的局部应力可能会占主导地位。尽管烧绿石/萤石混合物具有明显减少的晶粒，但它仅表现出中等断裂韧性，表明晶粒细化对增韧的影响可以忽略不计。此外，由无序氧空位引起的原子压应力的随机分布有利于增韧。这项研究突出了增韧的原子压应力，为未来新型热障涂层的设计提供了指导。