Non-Thermal Plasma Synthesis of Plasmonic Zirconium Nitride Nanoparticles and Oxidation Mitigation

Localized surface plasmon resonance (LSPR) has garnered interest in a variety of fields recently, such as photocatalysis, photovoltaics, biophotonics, spectroscopy, sensing, and wave-guiding. Cost and production concerns motivate the search for plasmonic materials that absorb visible light alternative to precious metals, like Group IV transition metal-nitrides. We present a novel technique for the synthesis of plasmonic zirconium nitride (ZrN) nanoparticles using a scalable non-thermal plasma process. The synthesized particles exhibit a plasmonic absorption peak within the visible spectrum, tunable from 530 nm to 700 nm. The crystalline ZrN particles have a cubic rock salt structure and a tunable size distribution below 10 nm. We further developed a modular non-thermal plasma system that coats the particles with amorphous silicon nitride in-flight. This coating acts as an oxygen barrier that prevents oxidation of the ZrN core when the material is exposed to atmosphere and yields blue-shifted and increased-intensity absorption.