Phase relations and thermomechanical properties of (Gd2Zr2O7)1−x(YbSZ)x based thermal barrier coatings (0 ≤ x ≤ 0.98)

Doped Gd 2 Zr 2 O 7 materials have interesting properties as thermal barrier coatings (TBC) to replace the YSZ topcoats traditionally used. Here we investigate the thermomechanical properties and phase relations of Gd 2 Zr 2 O 7 (GZO) alloyed with 5 mol% Yb 2 O 3 stabilized ZrO 2 (YbSZ) in the composition range (Gd 2 Zr 2 O 7 ) 1− x (YbSZ) x , 0 ≤ x ≤ 0.98. With increasing YbSZ content, phase transformations from ordered to disordered pyrochlore to fluorite and tetragonal structures were observed. The thermal expansion coefficient (TEC) and Vickers hardness were correlated showing a maximum hardness (~ 11.5 GPa) and minimum TEC at x = 0.82. At 1000 °C, the TEC for the end members, x = 0 and 0.98, were 11.4 and 11.3 × 10 –6 K −1 , respectively. The fracture toughness, K IC , showed an average value around 1.5 MPa m 0.5 for x ≤ 0.93 and increased significantly at x = 0.98 reaching 5.4 MPa m 0.5 due to the presence of a ferroelastic phase. For TBC applications, compounds with x = 0.98 show promise due to high TEC and high K IC . Graphic abstract Fig. 5a summarize the most important results in the manuscript. Showing a significant increase in fracture toughness for compositions with x=0.98.