Refractory Metals and Oxides for High-Temperature Structural Color Filters

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Refractory metals offer high-temperature stability and tunable optical properties for photonics.
• Previous research often overlooks the high-temperature optical behavior of these materials.
• Structural color relies on thin-film interference for color generation.

Purpose of the Study:

• To demonstrate structural color pixels using refractory metals (Ru, Ta, W) for high-temperature applications.
• To investigate the optical properties and dielectric functions of these metals up to 600 °C in an oxygenated environment.
• To explore the potential of metal oxide/metal structures for tunable high-temperature color filters.

Main Methods:

• Fabrication of structural color pixels using Ruthenium (Ru), Tantalum (Ta), and Tungsten (W).
• In situ oxidation to form nanometer-scale metal oxide thin-film bilayers.
• Optical characterization and dielectric function determination up to 600 °C.
• Optical simulations of two-layer metal oxide/metal reflector structures.

Main Results:

• Demonstrated structural color pixels based on Ru, Ta, and W refractory metals.
• Quantified optical behavior and dielectric functions up to 600 °C.
• Observed vibrant color changes due to high-temperature induced thin-film interference.
• Simulations confirmed a wide range of achievable hues with the proposed structures.

Conclusions:

• Refractory metal-based structural color pixels are suitable for high-temperature photonic applications.
• Ta-based structures offer high-temperature stability, while Ru and W provide reversible color filtering options.
• The metal oxide/metal approach enables conformal coatings for diverse colors across a broad gamut at elevated temperatures.