Photonic response and temperature evolution of SiO₂/TiO₂ multilayers.

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Investigating the thermal stability and optical properties of dielectric nanomultilayers is crucial for advanced applications.
• SiO2/TiO2 nanomultilayers offer unique photonic properties relevant to high-temperature environments.

Purpose of the Study:

• To investigate the microstructural and optical reflectivity response of SiO2/TiO2 nanomultilayers as a function of temperature.
• To evaluate the material's performance up to its melting point for potential high-temperature coating applications.

Main Methods:

• Differential thermal analysis (DTA) to study thermal behavior.
• X-ray powder diffraction for phase composition analysis.
• Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) for microstructural investigation.

Main Results:

• High broadband reflectivities (>75% from 600-1600 nm) were observed up to 1350°C.
• Phase transformations occurred from anatase TiO2 to rutile and amorphous SiO2 to cristobalite.
• Despite structural changes, photonic characteristics were retained, with lower melting temperatures for nm-sized samples compared to bulk.

Conclusions:

• SiO2/TiO2 nanomultilayers exhibit remarkable thermal stability and preserve optical reflectivity.
• Limited mutual solubility and retained optical properties make them suitable for high-temperature photonic coatings.
• Potential applications include photovoltaics, aerospace re-entry systems, and gas turbines.