Potential thermal barrier coating materials: RE 3 NbO 7 ( RE =La, Nd, Sm, Eu, Gd, Dy) ceramics

Abstract In this work, RE 3 NbO 7 ceramics are synthesized via solid‐state reaction and the phase structure is characterized by X‐ray diffraction and Raman spectroscopy. The relationship between crystal structure and thermophysical properties is determined. Except Sm 3 NbO 7 , each RE 3 NbO 7 exhibits excellent high‐temperature phase stability. The thermal expansion coefficients increase with the decreasing RE 3+ ionic radius, which depends on the decreasing crystal lattice energy and the maximum value reaches 11.0 × 10 −6 K −1 at 1200°C. The minimum thermal conductivity of RE 3 NbO 7 reaches 1.0 W m −1 K −1 and the glass‐like thermal conductivity of Dy 3 NbO 7 is dominant by the high concentration of oxygen vacancy and the local structural order. The outstanding thermophysical properties pronounce that RE 3 NbO 7 ceramics are potential thermal barrier coating materials.