Second-phase composite engineering endows Gd3TaO7-based ceramic with broadband infrared radiation

Abstract

High-temperature infrared (IR) radiation materials with broadband high emissivity, low thermal conductivity, and high fracture toughness are urgently needed for radiative heat management. Here, we report a Gd₃TaO₇/GdFeO₃ composite ceramic that integrates a broadband (0.78–14 ​μm) high emissivity (close to 0.9), low thermal conductivity (1.62 ​W ​m⁻¹ ​K⁻¹), and fracture toughness (2.3 ​MPa ​m^1/2, close to YSZ). Through the introduction of second-phase GdFeO₃, many lattice distortions, multimode vibrations, and additional oxygen vacancies (O_v) contribute to an increase in the broad-band emissivity of the composite ceramics (especially in the 2.5–6 ​μm band, nearly 5 times greater than that of Gd₃TaO₇). This high IR emissivity significantly suppresses the elevated photonic thermal conductivity at high temperatures, resulting in ultralow thermal conductivity. Moreover, the stable atomic arrangement within the two phases contributed to the impressive high-temperature stability (1773 ​K, 200 ​h). The improved fracture toughness is attributed primarily to the presence of the second phase promoting crack tip deflection, bridging and branching, which prevent crack expansion. All the advantages render this second-phase composite strategy fully competitive in the development of a new generation of superhigh-temperature radiative heat management materials.