Potential thermal barrier coating materials: RE3NbO7 (RE=La,Nd, Sm, Eu, Gd, Dy) ceramics

In this work, RE3NbO7 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 Sm3NbO7, each RE3NbO7 exhibits excellent high-temperature phase stability. The thermal expansion coefficients increase with the decreasing RE3+ ionic radius, which depends on the decreasing crystal lattice energy and the maximum value reaches 11.0x10(-6)K(-1) at 1200 degrees C. The minimum thermal conductivity of RE3NbO7 reaches 1.0Wm(-1)K(-1) and the glass-like thermal conductivity of Dy3NbO7 is dominant by the high concentration of oxygen vacancy and the local structural order. The outstanding thermophysical properties pronounce that RE3NbO7 ceramics are potential thermal barrier coating materials.