A new TBC material: (La0.2Gd0.2Y0.2Sm0.2Ce0.2)2Zr2O7 high-entropy oxide

In this study, (La0.2Gd0.2Y0.2Sm0.2Ce0.2)2Zr2O7((LGYSC)ZO)), as a new type of thermal barrier coating material, was designed and synthesized. The lattice structure, microstructure, optical, thermophysical, and mechanical properties of the (LGYSC)ZO high-entropy oxide were also investigated. The results showed that a phase-pure pyrochlore-structure (LGYSC)ZO high-entropy oxide, which has a uniform elemental distribution at high temperatures, was successfully synthesized. In addition, the UV–Vis diffuse reflectance spectra results show that (LGYSC)ZO high-entropy oxide has direct and indirect bandgap widths of 3.10eν and 2.51eν, respectively. Infrared (IR) spectra of (LGYSC)ZO high-entropy oxide patterns were measured. The infrared spectra results show that the (LGYSC)ZO high-entropy oxide has better high temperature thermal radiation shielding performance than yttria stabilized zirconia(YSZ). According to the measured result by laser flash method, the thermal conductivity of (LGYSC)ZO high-entropy oxide is at range from 1.18 W m−1 K−1 to 1.37 W m−1 K−1 in the temperature regime from 200 °C to 1000 °C after porosity correction. The coefficient of thermal expansion (CTE) of (LGYSC)ZO high-entropy oxides is at range from about 7.79 × 10−6 k−1 to 11.1 × 10−6 k−1 corresponding temperature from 90 °C to 1000 °C. The mechanical properties of (LGYSC)ZO high-entropy oxides were also investigated, and the hardness and fracture toughness of (LGYSC)ZO high-entropy oxide were 6.61 GPa and 1.27 MPa m1/2, respectively. Therefore, the results indicate that (LGYSC)ZO has excellent properties as a promising thermal barrier coating material.