Yb ₂ O ₃ ‐Gd ₂ O ₃ codoped strontium zirconate composite ceramics for potential thermal barrier coating applications

Abstract Strontium zirconate (SrZrO ₃ ) has been considered as a promising thermal barrier coating (TBC) material for application in gas turbine engines; however, the phase transition problem limits its application. In this study, an Yb ₂ O ₃ and Gd ₂ O ₃ codoped SrZrO ₃ system with excellent properties was reported. Yb ₂ O ₃ ‐Gd ₂ O ₃ codoped SrZrO ₃ ceramic powders [Sr _0.8 (Zr _0.9 Yb _0.05 Gd _0.05 )O _2.75 , SZYG/YGZO], [Sr(Zr _0.9 Yb _0.05 Gd _0.05 )O _2.95 , SZYG] and pure SrZrO ₃ (SZO) powders were produced by a conventional solid‐state reaction method. The XRD and Raman results show that, the composite SZYG/YGZO ceramics consist of the SZO and Yb _0.5 Zr _0.5 O _1.75 phases with a low thermal conductivity of ~1.3 W/(m·K) at 1000°C, which is at least 40% lower than that of the SZO ceramics. The TG‐DSC results show that the SZYG/YGZO ceramics have no phase transition in the temperature range of 600 to 1400°C. The thermal expansion coefficient of the SZYG/YGZO ceramics reaches 10.9 × 10 ⁻⁶ K ⁻¹ (1250°C). In addition, the fracture toughness of the SZYG/YGZO ceramics increases by more than 30% compared with the SZO ceramics, and this can be attributed to the presence of the Yb _0.5 Zr _0.5 O _1.75 phase.