Synthesis of ZrN–SiO2 core–shell particles by a sol–gel process and use as particle-based structured coloring material

ZrN–SiO₂ core–shell particles were prepared, where the ZrN core nanoparticles and SiO₂ shell were designed to exhibit localized surface plasmon resonances (LSPRs) and structural coloring. The heating of ZrO₂ nanoparticles with Mg₃N₂ under a nitrogen gas flow produced ZrN nanoparticles with a diameter in the range of 10–20 nm. The dispersion of ZrN nanoparticles in water exhibited an absorption maximum at approximately 700 nm owing to LSPRs. An SiO₂ shell was formed on the ZrN nanoparticles using a sol–gel process. Scanning transmission electron microscopy confirmed the formation of ZrN–SiO₂ core–shell particles containing ZrN particles with a diameter of approximately 10 nm. The SiO₂ shell thickness was controlled by varying the reaction time to form SiO₂. The use of particles as a structural component of a structural color material owing to the high uniformity of the size of obtained core–shell particles was investigated. The obtained ZrN–SiO₂ core–shell particles were arrayed on a glass substrate using a layer-by-layer method. The particle-stacked film of the ZrN–SiO₂ core–shell particles exhibited the maximum reflection depending on the particle size of the SiO₂ shell.