Infrared Stealth Coating with Tunable Structural Color Based on ZnO Spheres

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Developing low infrared (IR) emissive coatings with tunable structural color is crucial for enhancing the infrared-visible stealth performance of military equipment.
• Zinc oxide (ZnO) possesses a high refractive index and inherently low IR emissivity, making it a suitable material for such applications.

Purpose of the Study:

• To construct photonic structures using uniform ZnO spheres that exhibit both adjustable structural color and low IR emissivity.
• To investigate the IR emissivity characteristics of ZnO photonic crystals (PCs) and amorphous photonic crystals (APCs) in the 3-5 µm range.

Main Methods:

• Utilized uniform ZnO spheres as building units to create photonic crystal (PC) and amorphous photonic crystal (APC) structures.
• Measured the IR emissivity of the fabricated ZnO structures at different temperatures (25°C and 300°C).

Main Results:

• The ZnO PCs and APCs demonstrated tunable structural colors due to their photonic bandgap properties.
• Both ZnO PC and APC structures showed low IR emissivity in the 3-5 µm range, with values decreasing significantly at higher temperatures (e.g., from 0.483 to 0.295 for ZnO PC at 300°C).
• The developed structures exhibit good thermal and light stability and can be applied to various surfaces.

Conclusions:

• This work presents a simple and effective method for fabricating materials with excellent infrared-visible stealth performance.
• The developed ZnO-based photonic structures hold promise for camouflage applications, expanding the use of ZnO PCs and APCs coatings.