Nanoscale Electronic-Structural Synergy Induced by Sr Doping Enables Record-Low Room-Temperature Infrared Emissivity in SmCoO3-Based Perovskites
Infrared stealth technology demands materials with simultaneously low infrared emissivity and robust environmental stability. Traditional coatings suffer from high emissivity or poor thermal stability. Here, we report Sr-doped SmCoO3 perovskite ceramics achieving a record-low room-temperature infrared emissivity of 0.12 in the 8–14 μm atmospheric window. Systematic doping (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) via solid-phase synthesis reveals that Sr substitution induces a Co3+/Co4+ mixed valence state, increases oxygen vacancy concentration, and distorts the lattice. First-principles calculations (CASTEP) confirm that doping narrows the bandgap from 1.8 eV to 0.9 eV and enhances the double-exchange interaction, boosting carrier concentration and mobility. The optimized composition (x = 0.3) exhibits an electrical conductivity of 1.2×10^3 S/cm and a carrier density of 3.5×10^21 cm^-3, leading to strong infrared reflection. The material maintains emissivity below 0.15 after 100 hours of thermal cycling at 300°C and 500 hours of humidity exposure (85°C/85% RH), demonstrating exceptional environmental durability. This work establishes a new paradigm for designing high-performance inorganic infrared stealth materials via electronic-structural synergy.