Thermally stable 2D YMnO₃ enabling blue visible camouflage with mid-infrared transparency

Blue coloration is highly desirable for visible camouflage in aerospace environments, while effective mid-infrared camouflage requires surface layers that do not disturb the underlying radiative boundary under thermal detection. Achieving these two functions simultaneously at elevated temperatures remains fundamentally challenging, because the electronic processes responsible for blue visible appearance are intrinsically coupled to lattice polarization and phonon-mediated optical responses, which commonly destabilize the mid-infrared transparency window. Here, this long-standing constraint is overcome by realizing a two-dimensional hexagonal YMnO₃ system through microwave-shock synthesis that integrates thermal robustness, a blue visible appearance, and mid-infrared transparency. The non-equilibrium synthesis kinetically stabilizes a low-dimensional oxide architecture in which dimensional confinement suppresses long-range polarization contributions, while rigid Mn-O polyhedral units reinforce short-range bonding. These cooperative effects reduce the splitting between longitudinal and transverse optical phonons and suppress Reststrahlen-band expansion, enabling visible coloration to coexist with mid-infrared camouflage even under high-temperature conditions. This work establishes a structure-based, non-equilibrium strategy for decoupling visible and infrared optical constraints in thermally stable oxides, offering a general paradigm for high-temperature, cross-spectral camouflage materials.