Anti‐Thermal Quenching of Thermal Barrier Ceramics Enables High‐Resolution 3D Ultrahigh Temperature Imaging

The extremely high‐temperature environment of aerospace engines raises an urgent demand for the development of smart thermal sensing and barrier (TSB) ceramics to protect engine blades. However, it remains a significant challenge for smart TSB materials to simultaneously realize the dual functions of 3D ultrahigh temperature sensing and superior thermal barrier performance. Here, we develop a medium‐entropy ceramic with a composition of (Y 0.25 Gd 0.25 Lu 0.25 Sc 0.25 ) 2 Zr 2 O 7 :Dy,Tm to overcome the above bottleneck. We discover a new cross‐relaxation tuned anti‐thermal quenching mechanism in Tm 3+ ions, which extends the temperature sensing limit up to 1300 K. By utilizing the contrast in high‐temperature response characteristics of Tm 3+ and Dy 3+ ions, the ceramics achieve a broad sensing range of 300–1300 K with a thermometry sensitivity of 0.74% K −1 at high temperatures, outperforming existing reports. Importantly, we demonstrate its capability for 3D real‐time high‐temperature imaging at a high spatial resolution of 93.3 µm/pixel. Our design also significantly improves the overall thermal barrier performance, including thermal properties, corrosion and sintering resistance, and mechanical properties. Our work provides new insights into high‐temperature photophysics and paves the way for the development of smart TSB materials for aerospace applications.