Enhanced anti‐deliquescent property and ultralow thermal conductivity of magnetoplumbite‐type LnMeAl11O19 materials for thermal barrier coating

Magnetoplumbite‐type LaMgAl₁₁O₁₉ ceramic has been proposed as one of promising candidates for the next generation thermal barrier coatings (TBCs) due to its low thermal conductivity. However, LaMgAl₁₁O₁₉ shows poor water‐resistance with significant weight loss at elevated temperatures in water‐containing atmosphere. In this work, we revealed that the essential reason for the poor water‐resistance of magnetoplumbite‐type LaMgAl₁₁O₁₉ ceramic is Mg²⁺ migration from the intrinsic site under moisture environment. And then an effective approach was proposed to improve its anti‐deliquescent property by completely substituting divalent alkaline earth ions Mg²⁺ with Zn²⁺. Finally, a panoscopic strategy was proposed to further lower thermal conductivity through co‐substituting La and Zn sites in LaZnAl₁₁O₁₉ with trivalent and divalent transition metal ions. The mechanism for the lowered thermal conductivity is due to the panoscopic approach, which providing all‐scale hierarchical architectures of phonon scattering mechanisms. The excellent anti‐moisture performance and ultralow thermal conductivity endow the LaZnAl₁₁O₁₉ based ceramics as a kind of promising candidates for advanced thermal barrier coatings.