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

In this paper, a series of solid solutions ceramics of (AlxGd1-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)G(1-x))(3)TaO7 ceramics is weberite in spite of the content of Al3+ is up to 5 mol.%. The thermal conductivities of (AlxGd1-x)(3)TaO7 ceramics range from 1.37 W.m(-1) K-1 to 1.47 W.m(-1) K-1 at 900 degrees C, which is much lower than that of 7-8 YSZ (about 2.5 W.m(-1) K-1). The thermal expansion coefficients (TECs) of (AlxGd1-x)(3)TaO7 ceramics vary in the range of 6-10 x 10(-6) K-1 within the temperature range 100-1200 degrees C, and the values are close to the TECs of 7-8 YSZ. Given the low thermal conductivity and high thermal expansion coefficients of (AlxGd1-x)(3)TaO7 ceramics, they have the potential to be the next generational thermal barrier coating materials.