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Due to the features of fingerprints, which include considerable diversity and invariability, latent fingerprint (LFP) detection has become a crucial part of criminal investigation. Its environmental friendliness, the powder dusting method is now preferred to visualize LFPs. Applicability of this method is severely constrained by substantial flaws like limited resolution, poor sensitivity, and significant background interference. By using the simple solution approach, we have presented BiOCl:Er3+ (1–9 mol %) phosphors to address these problems. An X-ray diffraction investigation verified the tetragonal structure of the BiOCl:Er3+. Transmission electron microscopy and high-resolution transmission electron microscopy studies are used to analyse the particle size and interplanar distances. Scanning electron microscopic images clearly revealed the layered structures with micron sized particles. Additionally, the optimized BiOCl:Er3+ (5 mol%) phosphor is used to detect LFP on diverse surfaces by utilising the powder dusting method. Under 365 nm light, phosphor displayed all the necessary characteristics for level I-III of LFP detection on a variety of surfaces. The pixel profile's fluctuating red value attests to the good affinity of BiOCl: Er3+ (5 mol%) phosphor for the fingerprint ridges. Additionally, it is possible to create writable inks by utilising the optimized phosphor such that hidden writings can be completed using a basic brush method and decoded under UV light illumination. The total findings demonstrated that the current phosphor is extremely capable for the production of LFP and anti-counterfeiting technologies. • A series of BiOCl: Er3+ layered structures were synthesized through a simple combustion synthesis method. • The optimized sample exhibit photochromic property. • BiOCl nanopowders can be used for visualization of latent fingerprints and data-security applications. [ABSTRACT FROM AUTHOR]

A red-emitting BaLa 2 ZnO 5 :Eu3+ nanophosphors (BLZO:Eu NPs) are successfully prepared via combustion method with the aid of variable fluxes. BLZO:Eu NPs without and with flux materials how they differ in terms of their structure, morphology, PL characteristics were discussed. Effect of these flux-materials on the crystal structure found to be minimal. However, the morphology, PL intensity and photoluminescence (PL) performance are all affected by the inclusion of these flux-materials. When compared to other fluxes, the NH 4 F flux-material more specifically may clearly increase the emission intensity by 2.5 times. Also it provides the best optimization in terms of quantum yield (QY). By tuning the flux material, the colour of the phosphor changes from orange to pure red. The optimized BLZO:3Eu/NH 4 F NPs performs better luminous labelling platform for latent fingerprint detection and anti-counterfeiting applications. Overall findings overwhelmingly support the employment of the BLZO:3Eu/NH 4 F phosphor in photonic devices, dermatoglyphics and data security applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the distinctiveness and perseverance of the friction ridges in fingerprints (FPs), latent fingerprints (LFPs) and lip prints (LPs) are two most significant types of evidence at crime scene. Therefore, it is essential in forensic science to develop a reliable method to detect LFPs and LPs. Traditional detection methods still face a number of difficulties, such as limited sensitivity, low contrast, strong background, and complex processing stages. We proposed a method for visualization of LFPs and LPs by utilizing La 2 CaZnO 5 :Dy3+ (1–5 mol %) (LCZO: Dy) phosphor using a solution combustion method. The crystal structure, phase purity, particle morphology, photoluminescence (PL) properties of the resulting phosphors were then characterized in detail. SEM images suggested that the obtained phosphors are non-uniform shapes and agglomerated to big particles. The photophysical properties of Dy3+ doped phosphors are analyzed by exploiting their photoluminescence excitation (PLE) and emission profiles. The emission profiles of all the doped samples exhibit sharp emission lines centred at ∼481, 573, and 667 nm, which are ascribed to 4F 9/2 → 6H 15/2 , 4F 9/2 → 6H 13/2 , and 4F 9/2 → 6H 11/2 intra configurational transitions of Dy3+ ion, correspondingly. The optimum doping concentration of LCZO: Dy phosphor was 4 mol%, and the dominant factor of concentration quenching effect is the nearest-neighbor ions interaction. The chromaticity coordinates of International Committee LCZO: Dy were located in the yellow color area. In addition, LCZO: 4Dy phosphor can well visualize the LFP image and LP image. The levels 1–3 features of fingerprint and groove pattern of lip print can be easily recognised with high resolution and contrast. The experimental results showed La 2 CaZnO 5 :Dy3+ can be well applied to advanced forensic investigation. • For the first time, a La 2 CaZnO 5 :Dy 3+ (1–5 mol%) phosphors was prepared via solution combustion method. • Using La 2 CaZnO 5 :Dy 3+ phosphor, latent fingerprint minutiae features can be identified. • La 2 CaZnO 5 :Dy 3+ phosphor is also used as a prominent candidate in lip print Applications. [ABSTRACT FROM AUTHOR]

Eu2+ doped Sr 2 MgSi 2 O 7 nanophosphors (SMSO:Eu2+ NPs) have been synthesized by using solid-state reaction method. As Eu2+ concentration increases, energy transfer (ET) between Eu2+ ions dominated attributed to dipole-dipole (d-d) interaction. Besides, temperature-dependent photoluminescence (PL) of optimized SMSO:7Eu2+ NPs is investigated. The emission shifts towards blue with increased temperature. From the temperature-dependent emission, the activation energy, is ∼0.40 eV. CIE coordinate is (0.1476, 0.1141) with CCT value of 3633 K. The optimized phosphor is used to detect LFPs on various surfaces. The level I-III features are clearly identified under UV 365 nm excitation. Several pores properties namely pore size, shape, number, position, type and pore inter-distance are analyzed in detail. The anti-counterfeiting results clearly showed the enhanced intensity owing to its nano-size, reduced light dispersion and increased light absorption. The overall results clearly suggest the optimized SMSO:7Eu2+ NPs are promising luminescent platform for nUV light-emitting diode (LED) and latent fingerprint (LFP) applications. [Display omitted] [ABSTRACT FROM AUTHOR]

• CaLa 2 ZnO 5 :Eu3+ were prepared by solution combustion method. • Suitable for warm white light applications. • CLZO:5Eu NPs distinguish grooves & ridges clearly and recognize the level-3details also. • luminous security ink's showed better chemical, photo, and stability in an ambient environment. A novel class of cutting-edge materials known as photoluminescent (PL) nanophosphors (NPs) based on inorganic compounds has the potential to be used in a variety of industries, including chemo sensors, optical devices, drug delivery systems, anticounterfeiting inks (AC), and bioimaging. In the present work, we report a simple propellent combustion method for the preparation of CaLa 2 ZnO 5 :Eu3+ (1–9 mol%) (CLZO:Eu) NPs. The optimized powders are utilized for strategic applications such as white light emitting diodes (WLEDs), latent Finger Print (LFP) detection and anti-counterfeiting (AC) applications. According to the PL spectral profiles, the dazzling red emission has been observed at 626 nm (5D 0 →7F 2) from the CLZO:Eu NPs under the excitation of 395 nm. The ideal activator concentration is determined to be 5 mol%, and the quadrupole-quadrupole interactions are attributed for the concentration quenching that resulted from the over doping. The CIE coordinates (x-y) are determined to be (0.6206, 0.3732) for CLZO:5Eu NPs. The correlated colour temperature (CCT) value for the optimized sample is determined to be between 2000 and 5000 K, indicating that it may be a more suitable red component for warm white light applications. The fabricated PL NPs for AC labels exhibited strong fluorescence emission and good stability, under UV light, different chemical environments, and ambient environments making them suitable for a variety of uses, including environmentally friendly PL inks for anti-counterfeiting technologies. CLZO:5Eu NPs, on the other hand, can clearly distinguish between grooves and ridges and recognize the detail of levels 1–3. The overall results clearly showed that, the present material has great potential for multilevel anticounterfeiting strategies to achieve high-security encryption. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the outstanding optical qualities, stimulation-responsive luminous materials have drawn a lot of attention in the anti-counterfeiting application. In this work, the feasibility of applying BaLa 2 ZnO 5 :Bi3+ (BLZO:Bi3+) (0.5–4.0 mol%) phosphor, to multiple stimuli anti-counterfeiting (AC) and latent fingerprint visualization (LFP) is explored and discussed. The prepared luminous security ink from the optimized phosphor is effectively used for the multiple stimuli AC under 325, 355 and 375 nm excitation wavelengths. The results show that the fabricated luminous security ink is highly stable in ultraviolet (UV) light, various chemical environments, and ambient conditions. In addition, powder dusting method is utilized for LFPs detection on porous, non-porous and semi-porous surfaces under different excitation wavelengths. The multilevel features of the phosphor-attached LFP could be identified clearly in all the surfaces. The high-resolution LFPs imaging by scanning electron microscope (SEM) pictures, providing us more precise details on the width, distance, distribution, and forms of fingerprint (FP) pores. All the results reveal that the phosphor is a good potential choice for AC and LFP detection. [Display omitted] • At excitation wavelengths of 325, 355, and 375 nm, the BLZO:Bi3+ phosphor can produce blue, baby blue, and blue-green light. • latent fingerprints clearly captured by using the optimized phosphor in powder dusting method. • The application of the prepared luminous security ink for multiple stimuli anti-counterfeiting has been effectively proven. • Results show that luminous security ink is highly stable in UV light, various chemical environments, and ambient conditions. [ABSTRACT FROM AUTHOR]

Advanced forensic applications and optoelectronics both heavily rely on rare earth (RE) element activated luminous phosphor materials. We have used a single-phase green-emitting Sr 9 Al 6 O 18 :Er3+ (1–11 mol%) (SAO:Er) nanophosphor to detect latent fingerprints (LFPs) and white light-emitting diodes (w-LEDs). The X-ray diffraction and Rietveld refinement were used to examine crystallographic data. The phosphors showed vivid-green luminescence when stimulated by 378 nm, a near ultraviolet (nUV). The concentration of Er3+ ions is observed to affect the photoluminescence emission (PLE) intensity, reaching its highest value for 5 mol% doping. The optimized phosphor is used in latent finger print (LFP), lip print (LP) and anti-counterfeiting (AC) applications. Under 378 nm excitation, multilevel features of the phosphor-attached LFPs could be clearly identified. The high colour contrast between the ridge and valley lines made for an excellent observation. We have developed simple brush and screen-printing methods for creating a variety of patterns using our custom anti-counterfeit security ink. In addition to this, the obtained AC tags exhibit high resolution and long-term durability. These characteristics clearly demonstrated that the current phosphor is an excellent luminescent material for data storage applications. • Green-emitting Sr 9 Al 6 O 18 :Er3+ nanophosphors were obtained by solution combustion. • Vivid-green luminescence was obtained when stimulated by 378 nm near ultraviolet. • The prepared fluorescent ink is highly beneficial for high-end security encryption. • Anti-counterfeiting labels exhibit high resolution and long-term durability. [ABSTRACT FROM AUTHOR]

The development of technology related to forensic is still beneficial and requires for continued research and the implementation of evaluation procedures. In this context, the current work focuses on the production of blue light emitting La 2 Zr 2 O 7 nanophosphors (LZO) (NPs) doped with Ce3+ ions and surface modified with oleyl amine (OA) are employed for data security and latent fingerprint imaging applications. The formation of the pure pyrochlore phase is confirmed from powder X-ray diffraction (PXRD). The structural analysis is performed from Rietveld refinement. Scanning electron microscope (SEM) and transmission electron microscopy are used to study the surface morphology and crystallite size estimation respectively. Photoluminescence (PL) emission spectra exhibit all the characteristic emission peaks of Ce3+ ions. The surface modified NPs by OA exhibited 2-fold enhancement in the emission intensity as compared to unmodified NPs, which is due to effective intramolecular energy transfers from coordinated ligands to the activated Ce3+ ions, called the antenna effect. The most trustworthy proof of a person's identity can be found in the ridge characteristics revealed by the observed latent fingerprints employing surface modified nanophosphor. The chemical bonding between the nanophosphor and chemical components contained in the fingerprints, which enables the majority of authenticated sweat pores, further confirmed by high resolution photographs of formed latent fingerprints. The NPs which have OA grafted onto them can be made into security ink that can be used to create hidden inscriptions with a basic brush technique as well as screen print and decoded under 283 nm light illumination. The features of the NPs, which is a real-time option for latent fingerprint formation and anti-counterfeiting technologies are significantly improved by the surface modification technique. • A series of La 2 Zr 2 O 7 : Ce3+ NPs were synthesized through a combustion synthesis method. • Optimized sample was further surface modified by utilizing OA as a surface modifier. • Surface modified NPs may be used for visualization of latent fingerprints and anti-counterfeiting applications. [ABSTRACT FROM AUTHOR]