High-Temperature-Resistant Mid-Infrared Capability for Extreme Energy Systems.

Extreme thermal environments encountered in hypersonic flight, space infrastructure, high-temperature energy conversion, and harsh industrial processes place mid-infrared radiation at the center of heat exchange, sensing, and energy management. As operating temperatures and environmental aggressiveness increase, conventional room temperature optical design becomes an unreliable predictor of in-service behavior, while the stability of radiative properties under coupled thermal, chemical, and mechanical loads emerges as a critical bottleneck. Despite extensive progress in individual material systems, a unified understanding that links material structure, degradation pathways, and durable mid-infrared functionality remains lacking. This review provides a structure-informed framework for high-temperature-resistant mid-infrared materials, resolving the field into three functional classes of high reflectance, high absorptance or emittance, and high transmittance, and interpreting their performance through four governing structural determinants spanning electronic and defect structure, crystallography and phase stability, microstructure and mesostructure, and high-temperature surface and interface evolution. By consolidating material classes, spectral bands, functional metrics, and temperature limits into a coherent dataset, the review enables like-for-like comparison and the extraction of transferable design descriptors. This perspective couples radiative function with thermal survivability, offering design rules and a roadmap for developing predictable, field-qualified mid-infrared technologies capable of operating at the limits of temperature and energy flux.