Effects of atom- and phase-scale compressive stress on fracture toughness in yttrium-doped lanthanum zirconate solid solutions

Yanfei Wang, Ping Xiao, Huan Yang, Siqing Wang, Rongjun Liu, Yingbin Cao

    Research output: Contribution to journalArticlepeer-review

    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.

    Original languageEnglish
    Pages (from-to)6590-6600
    Number of pages11
    JournalCeramics International
    Volume44
    Issue number6
    Early online date10 Jan 2018
    DOIs
    Publication statusPublished - 15 Apr 2018

    Keywords

    • Atomic compressive stress
    • Cubic pyrochlores
    • Fracture toughness
    • Thermal barrier coatings
    • Toughening

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