Desired highly efficient Eu3+ activated GdCaAl3O7 orange-red emanating nanophosphors for UV excitable forensic and advanced information encryption and decryption applications

Abstract

In the present work, orange-red emitting Eu3+ (1–8 mol %) doped GdCaAl3O7 nanophosphors are prepared by a simple solution combustion route. X-ray diffraction studies reveal that the prepared phosphors are in the tetragonal phase without any additional impurity peaks. Morphological studies clearly show the irregularly shaped network-type structures of the phosphors. Under UV light excitation (∼393 nm), photoluminescence (PL) emission peaks are recorded at ∼578, 590, 617, 651, and 701 nm, which correspond to the 5D0→7F0, 1, 2, 3, 4 transitions of Eu3+ ions, respectively. The photometric properties of the prepared nanophosphors reveal color tuning from the orange-red region to the pure red region with a color purity of ∼88.14 %. The optimized GdCaAl3O7:Eu3+ (3 mol %) nanophosphor is evaluated from an application perspective by developing latent fingerprints and lip prints. The visualized latent fingerprints under ∼254 and 375 nm excitations undoubtedly reveal levels I–III ridge features on various surfaces. The developed lip prints can discriminate the Suzuki's and Tsuchihashi’s categories. The information encryption and decryption capabilities of the nanophosphor on various surfaces were investigated by following screen printing technology, dip-pen and brush mode. The printed patterns revealed sharp, high resolution, uniform ink distribution under ∼254 nm UV excitation and invisible upon normal light. The overall results revealed that prepared GdCaAl3O7:Eu3+ (1–8 mol %) NPs exhibit excellent structural stability and intensive PL emission endorsing its applicability wide scope of areas.