Thermal cycling behavior of Yb3+-Ce4+ co-doped La2Zr2O7-based TBCs: Experimental and theoretical research

The thermal cycling behavior of Yb3+-Ce4+-La2Zr2O7/YSZ (LYZCO/YSZ) TBCs was systematically investigated via experiment and first-principles calculation. Results suggest that ceramic grain boundary cracking is the root cause of LYZCO/YSZ TBCs thermal cycle failure. Compared to La2Zr2O7/YSZ TBCs, LYZCO/YSZ TBCs own an outstanding thermal cycle life at 1100 ℃, which is attributed to LYZCO's higher TEC (10.431×10-6/K, 1100 ℃) and lower thermal conductivity (1.299W/(m·K), 1100 ℃). Furthermore, Griffith's separation work of the LYZCO/YSZ interface is merely -0.576J/m2, implying that the LYZCO/YSZ TBCs are particularly prone to cracking at this interface. Weakly bonded La-O is the first site at this interface cracking.