Delving into the multifunctionality of Sr2NaMg2V3O12via RE3+ substitution for dual-mode temperature sensing, latent fingerprint detection and security inks

Abstract

Vanadate garnets are one of the exotic materials that exhibit multifunctionality, inevitable for the current scenario in materials science. Herein, the multifunctional aspects of Sr₂NaMg₂V₃O₁₂ and Sr₂NaMg₂V₃O₁₂:Sm³⁺/Eu³⁺ phosphors are discussed. The distinct thermal response of Sm³⁺ and VO₄³⁻ enabled the temperature sensing property in which a maximum relative temperature sensitivity of 2.01% K⁻¹ is obtained at 440 K, along with an average temperature uncertainty of ±1.0 K, high repeatability rate of 95%, and temperature resolution of <0.7 K. Negative thermal quenching was observed near the charge transfer band edge with the increase in temperature due to the thermal population of higher vibronic states. A rapid change in emission color with temperature rise for safety sign application was also observed. The prospects of Sr₂NaMg₂V₃O₁₂ based phosphors were investigated for latent fingerprint detection for the first time in vanadate garnets. Under 365 nm UV radiation, fluorescent images with good contrast were obtained from the powder-stained latent fingerprints, and pixel profile data was analysed thoroughly. As confirmed by the microstructure study, the relatively smaller size of the phosphor grains increased their adhesion on fingerprints. The primary, secondary, and tertiary levels of identification, including sweat pores, deltas, and bifurcations, were performed. The efficiency of powder-stained LFPs was verified after a long storage duration and for various substrates. The developed security inks were highly efficient and can reduce the risk of duplication of documents for anticounterfeiting. These results manifest the versatility of the Sr₂NaMg₂V₃O₁₂ and Sr₂NaMg₂V₃O₁₂:Sm³⁺/Eu³⁺ systems for multifunctional applications.