A novel approach to the synthesis of Zn2SiO4:Mn luminescent nanoparticles

Abstract

<p dir="ltr" style="text-align: justify;">In this study, manganese doped zinc sulfide nanoparticles&nbsp;with luminescence properties (Mn²⁺&nbsp;ions) were synthesized together&nbsp;with silica-aerogel particles. The&nbsp;effect of temperature variations on the optical properties of&nbsp;the composite&nbsp;was investigated. X-ray diffraction patterns (XRD) showed the transformation of ZnS (sphalerite) to Zn₂SiO₄&nbsp;(willemite) after heat treatment. Both silica aerogel and as-deposited SiO₂&ndash;ZnS:Mn nanocomposites contained nanoparticles with emission wavelength of up to 30&nbsp;nm. The heat treatment caused an obvious increase in the particle size to nanometer scale. Photoluminescence (PL) spectra revealed that ZnS:Mn possesses an emission peak at 590&nbsp;nm, which was quenched by increasing the Mn content above 2.5% mol. In the as-deposited SiO₂&ndash;ZnS:Mn spectra, an extra peak in the blue region was&nbsp;observed which is related to the silica structure. However, the heat treatment led to the appearance of strong green emission peak at 527&nbsp;nm due to the formation of willemite which was quenched at higher temperatures due to the change of structure from willemite to tridymite.&nbsp;Finally, two luminescent inks were produced by as-deposited and heat treated SiO₂&ndash;ZnS:Mn nanocomposites in water-based solvents as security inks.</p>