<p>This study mainly focuses on the effect of small amount additions of Eu³⁺ in substitution for Y³⁺ on the thermal conductivity of YSZ TBCs, and the evaluation of coatings resistance to severe thermal shock cycles. Eu³⁺ doped and undoped YSZ coatings were prepared by APS method. Thermal conductivity of the two coatings was measured and both types of coatings were subjected to thermal shock condition under a steady propane flame at 1100&#xa0;°C. Results showed that thermal conductivity of the YSZ:Eu coating is 10–19% lower than that of the YSZ coating at the same temperature, indicating that only 2&#xa0;mol% Eu³⁺ doping can effectively reduce the thermal conductivity of the YSZ TBCs. For the same treatment conditions, the interfacial fracture toughness of the YSZ:Eu coating is slightly higher than that of the YSZ coating and the TGO thickness is thinner, indicating that 2&#xa0;mol% Eu³⁺ doping is prone to inhibit the growth of TGO and improve the coating’s interfacial properties. Comparison between flame thermal shock and furnace isothermal / cyclic oxidation treatment confirmed that flame thermal shock is a more severe and destructive treatment as it results in higher densities of micro-cracks and pores within the TGO, thus inducing a lower interfacial fracture toughness value.</p>