High thermal stability and quantum yields of green-emitting Sr 3 Gd 2 (Si 3 O 9 ) 2 :Tb 3+ phosphor by co-doping Ce 3+

One material, many possibilities via enrichment of luminescence in La2Zr2O7:Tb3+ nanophosphors for forensic stimuli aided applications

Engineering a single material with multidirectional applications is crucial for improving productivity, low cost, flexibility, least power consumption, etc. To achieve these requirements, novel design structures and high-performance materials are in urgent need. Lanthanide-doped nanophosphors have the greatest strengths and ability in order to tune their applications in various dimensions. However, applications of nanophosphor in latent fingerprints visualization, anti-counterfeiting, and luminescent gels/films are still in their infancy. This study demonstrated a simple strategy to enhance the luminescence of Tb³⁺ (1-11 mol %) doped La₂Zr₂O₇ nanophosphors by conjugating various fluxes via a simple solution combustion route. The photoluminescence emission spectra reveal intense peaks at ~ 491, 546, 587, and 622 nm, which arises from ⁵D₄ → ⁷F_J (J = 6, 5, 4, 3) transitions of Tb³⁺ ions, respectively. The highest emission intensity was achieved in the NH₄Cl flux assisted nanophosphor as compared to NaBr and NH₄F assisted samples. The colorimetric images of fingerprints visualized using the optimized nanophosphor on forensic related surfaces exhibit level -III ridge details, including sweat pores, the width of the ridges, bifurcation angle, and the successive distance between sweat pores, etc. These results are decisive parameters that clearly support the statement "no two persons have ever been found to have the same fingerprints". The anti-counterfeiting security ink was formulated using optimized nanophosphor and various patterns were designed by simple screen printing and dip pen technologies. The encoded information was decrypted only under ultraviolet 254 nm light. All the designed patterns are exhibit not just what it looks/feel like and how better it works. As a synergetic contribution of enhanced luminescence of the prepared nanophosphor, the green-emissive films were fabricated, which display excellent flexibility, uniformity, and transparency in the normal and ultraviolet 254 nm light illumination. The aforementioned results revealed that the prepared NH₄Cl flux-assisted La₂Zr₂O₇: Tb³⁺(7 mol %) NPs are considered to be the best candidate for multi-dimensional applications.

A novel stibium phosphate, LiBa(SbO)2(PO4)3: synthesis, crystal structure and RE3+-activated (RE = Tb3+ and Eu3+) fluorescence performance

A new stibium phosphate, lithium barium bis(antimony oxide) tris(phosphate), LiBa(SbO)₂(PO₄)₃, was prepared by the molten salt method with LiF as the flux. The crystal structure consists of an original three-dimensional anionic framework of [(SbO)₂(PO₄)₃]_∞ built from PO₄ tetrahedra sharing their corners with SbO₆ octahedra. This framework delimits one-dimensional tunnels where the lithium(I) and barium(II) ions are located. The UV-Vis spectrum shows that LiBa(SbO)₂(PO₄)₃ was transparent from 350 to 800 nm, and is thus suitable as a luminescent host matrix. We then used Tb³⁺ and Eu³⁺ activators to test its luminous performance and the purities of the prepared phosphors were studied by powder X-ray diffraction analysis with Rietveld refinements. Photoluminescence (PL) studies reveal that the emission spectra of 1 mol% RE³⁺-doped (RE = Tb and Eu) samples can be excited by 371 and 394 nm light, emitting green and orange-red light, respectively, for Tb³⁺ and Eu³⁺. The CIE coordinates were measured to be (0.295, 0.571) and (0.6027, 0.3967), and the luminescent lifetimes were calculated as 0.178 and 1.159 ms, respectively.

Research progress of Mn doped phosphors

In this review article, Mn applications have been divided into three parts.