Potential thermal barrier coating materials: RE2FeTaO7 (RE = Y, Eu, Gd, Dy) compounds

Abstract In this paper, the A2B2O7-type compounds RE2FeTaO7 synthesized via a solid-state reaction were researched for high-temperature applications, and their thermophysical properties were documented for the first time. The relationships between thermophysical properties and structures of RE2FeTaO7 were established, the results show that the RE2FeTaO7 compounds have lower thermal conductivity (1.5–2.8 W m−1 K−1) than 8YSZ (2.4–3.0 W m−1 K−1) and La2Zr2O7 (2.0–2.8 W m−1 K−1) at temperature of 100–900 °C, implying their prominent thermal insulation performance. The thermal expansion coefficients (TECs, ∼9.2 × 10−6 K−1, 1200 °C) of RE2FeTaO7 are equivalent to La2Zr2O7 (∼9.0 × 10−6 K−1, 1200 °C). Furthermore, the excellent high-temperature phase stability, high hardness (∼10.2 GPa) and fracture toughness (∼1.7 MPa m1/2) jointly indicate that RE2FeTaO7 compounds are potential thermal barrier coating materials.