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Thermal barrier coating (TBC) materials employ ceramics with low thermal conductivity and excellent thermal durability. Recently, the gas turbine market has been increasing demand for a thermally insulating material applicable at higher operating temperatures above 1200 °C for greater thermal conversion efficiency. In this study, synthesized high-entropy A 2 Zr 2 O 7 zirconate ceramics incorporated five cations of a similar ionic radius into the A3+ cation site through a conventional solid-state reaction, and their superior thermophysical properties demonstrate. The HEO ceramics exhibited overall low thermal conductivity (from room temperature to 1000 °C) due to inducing lattice distortion in the crystal structure. In addition, divalent cations were added to the A3+ cation site to increase the oxygen vacancy at the structure, thereby suppressing the heat transfer caused by phonon. A 2 Zr 2 O 7 zirconate HEOs show enhanced thermal barrier performance than yttria-stabilized zirconia (YSZ), conventional TBC material, demonstrating a possibility of application as next-generation TBC materials. [ABSTRACT FROM AUTHOR]

The effects of substituting the B cation in A3BO7 ceramics on their thermal physical properties were investigated by applying a large mass difference. Y3(Nb1‐xTax)O7 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were synthesized, and their structural characteristics were determined. All the fabricated Y3(Nb1‐xTax)O7 ceramics showed defective fluorite structures and glass‐like low thermal conductivity (1.18−2.04 W/m∙K at 25°C) because of the highly distorted crystal structure and significant mass difference. Substitution with Ta5+ enhanced the sintering resistance, leading to superior thermal‐insulating performance via grain boundary scattering. Furthermore, the ceramics exhibited excellent coefficients of thermal expansion, implying the promising applicability of Y3(Nb1‐xTax)O7 as new thermal barrier materials. The effect of mass difference on the thermomechanical properties of the ceramics was examined, suggesting a simple strategy for engineering the chemical composition of new thermal barrier materials. [ABSTRACT FROM AUTHOR]

In this study, a high-entropy approach was employed to design a new single-phase A 2 B 2 O 7 oxide for thermal insulation applications. Multicomponent high-entropy oxides, containing up to seven different cations, were successfully synthesized in a single defective fluorite structure. We observed that the incorporation of the functional cation, Zn2+, effectively blocked the heat radiation phenomenon by reducing the photon mean free path, and further reduced the high-temperature thermal conductivity owing to the larger free carrier concentration originated from the large number of oxygen vacancies. Although a large concentration of Zn2+ caused a slight reduction in thermal expansion, this study suggests that functional cations can be easily incorporated; thus, expanding the material diversity beyond the typical doping levels to develop new thermal barrier materials. [ABSTRACT FROM AUTHOR]