Structure and thermal properties of Al2O3-doped Gd3TaO7 as potential thermal barrier coating

Abstract In this paper, a series of solid solutions ceramics of (Al x Gd 1-x ) 3 TaO 7 (x = 0, 0.01, 0.03, 0.05) were synthesized via solid-state reaction. X-ray diffraction (XRD) and Raman spectroscopy analysis indicated that the crystal structure of (Al x Gd 1-x ) 3 TaO 7 ceramics is weberite in spite of the content of Al 3+ is up to 5 mol.%. The thermal conductivities of (Al x Gd 1-x ) 3 TaO 7 ceramics range from 1.37 W∙m −1  K −1 to 1.47 W∙m −1  K −1 at 900 ℃, which is much lower than that of 7–8 YSZ (about 2.5 W∙m −1  K −1 ). The thermal expansion coefficients (TECs) of (Al x Gd 1-x ) 3 TaO 7 ceramics vary in the range of 6–10 × 10 -6  K -1 within the temperature range 100–1200 ℃, and the values are close to the TECs of 7–8 YSZ. Given the low thermal conductivity and high thermal expansion coefficients of (Al x Gd 1-x ) 3 TaO 7 ceramics, they have the potential to be the next generational thermal barrier coating materials.