Thermal Shielding GdTaO-Based Thermal Barrier Ceramic with Ultralow NIR Transmittance.

Most thermal barrier coating materials exhibit transparent/semi-transparent properties at higher temperatures, causing the surface heat flow to directly heat the substrate with infrared radiation, which significantly reduces the thermal barrier effectiveness. Herein, composite ceramic materials composed of GdFeO diffusely dispersed within the GdTaO are produced. Specifically, the 0.9GdTaO/0.1GdFeO composition demonstrates an ultra-low near-infrared (NIR) transmittance of less than 0.1% across the 400-2500 nm range. The introduction of variable-valence behavior and oxygen vacancies contribute to the narrow bandgap of GdFeO. The incorporated GdFeO produces extra multimode vibrations, resulting in the strong infrared emissivity of GdTaO/GdFeO composite ceramics. Besides, the refractive index difference between GdTaO and GdFeO can contribute to the potential photons scattering within the composites, severely impeding the infrared radiation penetration. The upward curvature of the thermal conductivity curve of 0.9GdTaO/0.1GdFeO at high temperature is significantly suppressed, confirming its excellent IR radiation shielding properties. Moreover, the GdTaO/ GdFeO composite ceramic exhibits thermal suitability, with a thermal expansion coefficient (9.47-9.67 × 10 K at 1400 °C) comparable to YSZ. These combined benefits position the GdTaO/ GdFeO composite ceramic system as a promising candidate for the development of infrared radiation shielding and high-emissivity thermal radiation materials.