Study of the physical properties of Yb

Driven by the need for high-performance thermal barrier coatings (TBCs) in geothermal power generation, (GdxYb1-x)2Zr2O7 ceramics (x = 0.5, 0.7, 0.9, 1) were synthesized via the solid-state reaction method. Their crystal structure (XRD), microstructure (SEM), mechanical properties (hardness, fracture toughness, Young's modulus), and thermal properties (diffusivity, conductivity) were systematically characterized to investigate the impact of Yb3+ doping. Major findings include: (1) All compositions exhibit a stable fluorite structure from room temperature to 873 K. (2) Yb3+ doping significantly reduces thermal conductivity, with the x = 0.7 composition achieving the minimum value of 0.858 W · m−1 · K−1 at 675 K (>30% lower than YSZ). (3) Doping enhances hardness and fracture toughness, peaking at 10.1 GPa and 2.23 MPa · m1/2 for the x = 0.5 composition. (4) Young's modulus shows a non-monotonic trend with doping. This work demonstrates that Yb3+-doped Gd2Zr2O7, particularly the x = 0.7 composition with ultralow thermal conductivity and sufficient mechanical strength, presents a promising candidate material for medium-high temperature (300–873 K) TBCs in geothermal applications, offering new avenues for durable coating design.