Evolution of CaGd₂ZnO₅:Eu³⁺ nanostructures for rapid visualization of latent fingerprints

Nanostructured inorganic materials are potential building blocks for advanced materials and devices with desired functions. Latent fingerprint technology requires cost-effective and high-quality luminescent nanomaterials to identify an individual with sufficient information. We report the synthesis and growth mechanism of novel nanostructured CaGd₂ZnO₃(CO₃)₂·H₂O and CaGd₂ZnO₅ materials through a urea- and EDTA-mediated hydrothermal process. The conversion from the carbonate to the oxide form is explained using physicochemical measurements. Furthermore, when doped with Eu³⁺ ions, CaGd₂ZnO₅ nanostructures exhibit superior luminescent properties to replace conventional red phosphors for latent fingerprint technology. In contrast to previously reported individual fluorescent nanoparticles, CaGd₂ZnO₅:5Eu³⁺ nanostructures provide three levels of identification with high-quality imaging on various hydrophilic and hydrophobic substrates. These properties demonstrate that CaGd₂ZnO₅:Eu³⁺ nanorod bundles are a promising luminescent material for solid-state lighting and latent fingerprint technologies.