Thermal Shielding Gd₃TaO₇-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 GdFeO₃ diffusely dispersed within the Gd₃TaO₇ are produced. Specifically, the 0.9Gd₃TaO₇/0.1GdFeO₃ 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 GdFeO₃. The incorporated GdFeO₃ produces extra multimode vibrations, resulting in the strong infrared emissivity of Gd₃TaO₇/GdFeO₃ composite ceramics. Besides, the refractive index difference between Gd₃TaO₇ and GdFeO₃ 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 0.9Gd₃TaO₇/0.1GdFeO₃ at high temperature is significantly suppressed, confirming its excellent IR radiation shielding properties. Moreover, the Gd₃TaO₇/ GdFeO₃ composite ceramic exhibits thermal suitability, with a thermal expansion coefficient (9.47-9.67 × 10^-6 K^-1 at 1400 °C) comparable to YSZ. These combined benefits position the Gd₃TaO₇/ GdFeO₃ composite ceramic system as a promising candidate for the development of infrared radiation shielding and high-emissivity thermal radiation materials.