A novel highly thermally stable phosphor powder Ba2LuSbO6: Eu3+ for latent fingerprint visualization

Abstract

In modern forensic science, fingerprints are critical evidence due to their uniqueness and difficulty to replicate. However, it is challenging to observe and identify some latent fingerprints (LFP), because alternative processing methods for recognition are often required. The use of Eu3+-doped phosphors, which emit red-orange light, presents an effective approach for enhancing the visibility of LFP. Eu3+-doped Ba2LuSbO6 (BLSO) phosphors were synthesized using a high-temperature solid-state method, aiming to improve the recognition of LFP for enhanced fingerprint identification. The phase structure of the fluorescent powder samples was analyzed through X-ray diffraction (XRD) combined with Rietveld refinement, as well as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Photoluminescence spectra of Ba2LuSbO6: xEu3+ phosphor samples exhibit orange-red emission peaks at 595 and 618 nm when excited by 250 nm deep ultraviolet light. Concentration quenching is observed at a doping concentration of 20 mol%. The Ba2LuSbO6: 0.2Eu3+ phosphor sample demonstrates exceptional thermal stability, with value of 92.50% at 423 K. The quantum efficiency of the Ba2LuSbO6: 0.2Eu3+ phosphor sample was evaluated using an integrating sphere, yielding an IQE of 79.34%. In order to visualize latent fingerprints (LFPs), hydrophilic BLSO: 0.2Eu3+ phosphors were transformed into hydrophobic BLSO: 0.2Eu3+@OA phosphors through a coating of oleic acid (OA). The BLSO: 0.2Eu3+@OA phosphor proves capable of generating dependable LFP fluorescence images with superior contrast and resolution. These findings underscore the significant potential for application of BLSO: 0.2Eu3+ products LFP visualization.