@article{Sang2026, 
author = {Ruige Sang and Hao Zhang and JingJing Liu and Xun He and Jiang Shi and Xun Xu and Shuwang Duo},
title = {Sm3+ substitution-mediated oxygen vacancy clustering: Theoretical analysis and experimental verification for suppressing low-temperature contraction of La2Ce2O7 ceramics},
year = {2026},
journal = {Journal of Advanced Ceramics},
volume = {15},
number = {3},
pages = {9221245},
keywords = {thermal barrier coating (TBC), Lanthanum cerate (La2Ce2O7), low-temperature contraction, isovalent substitution},
url = {https://www.sciopen.com/article/10.26599/JAC.2026.9221245},
doi = {10.26599/JAC.2026.9221245},
abstract = {Lanthanum cerate (La2Ce2O7, LC) is a promising thermal barrier coating (TBC) candidate with superior thermophysical properties over yttria-stabilized zirconia (YSZ), but its practical application is hindered by low-temperature thermal expansion coefficient (TEC) contraction. Previous studies primarily focused on regulating the oxygen vacancy concentration while neglecting the influences of vacancy distribution. Herein, we employ Sm3+ isovalent substitution for La3+ to maintain a constant vacancy concentration and isolate the vacancy distribution effects. The optimal composition (La0.8Sm0.2)2Ce2O7 significantly suppresses low-temperature contraction, reducing the linear shrinkage rate by ~88.5% and increasing the TEC by ~12.56% (to 12.37×10–6 K–1) compared with LC (10.99×10–6 K–1). Combining density functional theory (DFT) calculations and HR-TEM/AC-STEM characterization, we directly reveal Sm3+-induced oxygen vacancy clustering in LC-based ceramics. The underlying mechanism involves (i) randomly distributed free vacancies inducing contraction via vacancy-phonon coupling and local symmetry breaking; (ii) Sm3+ substitution introducing dislocations whose stress fields, together with Sm3+’s higher ionic potential, drive vacancy clustering; (iii) clustering reducing mobile vacancies and restoring lattice order, thereby suppressing contraction. This work confirms that LC's low-temperature contraction is coregulated by vacancy concentration and distribution, complementing existing concentration-modulation strategies.}
}