Systematic Analysis of the Crystal Chemistry and Eu3+ Spectroscopy along the Series of Double Perovskites Ca2LnSbO6 (Ln = La, Eu, Gd, Lu, and Y)

Self-reduction-induced BaMgP2O7:Eu2+/3+: a multi-stimuli-responsive phosphor for X-ray detection, anti-counterfeiting and optical thermometry

Mixed-valence Eu^2+/3+-activated phosphors have attracted wide attention due to their excellent luminescence tunability. Steady control of the Eu²⁺/Eu³⁺ ratio is the key to achieving reproducible Eu^2+/3+ co-doped materials. In this work, BaMgP₂O₇:xEu^2+/3+ (BMPO:Eu, x = 0.001-0.20) was successfully prepared by the traditional solid-state method in air. Eu³⁺ undergoes selective self-reduction at Ba²⁺ sites surrounded by a [P₂O₇] framework, leading to quantitive Eu²⁺/Eu³⁺. The phosphors exhibit a blue-violet emission band at ∼410 nm due to 5d-4f transitions of Eu²⁺ and a group of red emission peaks from ⁵D₀-⁷F_J of Eu³⁺. Controllable multicolor emissions are realized by regulating the Eu content and excitations. A linear response of overall luminescence intensity to irradiation dose makes the phosphor appropriate for X-ray detection. The combination of UV-blue excitation-dependent color evolution and X-ray luminescence qualifies the phosphors with great potential for multi-level anti-counterfeiting. In addition, Eu³⁺ presents abnormal anti-thermal quenching, so that the fluorescence intensity ratio (FIR) of Eu²⁺/Eu³⁺ changes in the temperature range of 300-520 K, suggesting a promising application in optical thermometry. Therefore, selectively partial self-reduction in a multi-cationic host is an effective strategy to design mixed-valence co-doped materials, providing a multiplicity of applications.

Luminescent Color-Adjustable Europium and Terbium Co-Doped Strontium Molybdate Phosphors Synthesized at Room Temperature Applied to Flexible Composite for LED Filter

In this study, terbium and europium rare-earth ions were single-doped and co-doped to synthesized SoMoO4 phosphor at room temperature. The samples prepared synthesized crystalline SrMoO4 powder by the co-precipitation. Samples had a tetragonal structure in XRD analysis and d(112) spacing was changed by rare-earth doping. As the amount of rare earth added increased, a secondary phase appeared, and the structure changed. The synthesized SrMoO4:Tb3+ phosphors showed a green light emission at 544 nm under 287 nm, SrMoO4:Eu3+ phosphors showed a red light emission at 613 nm under 290 nm, and SrMoO4:[Eu3+]/[Tb3+] phosphor showed a yellow-white light emission at 544 and 613 nm when excited at 287 nm. The synthesized phosphor exhibited a change in green and red luminescence intensity based on the amount of Eu3+ doped and showed strong red luminescence as the Eu3+ doping increased. To use the SrMoO4:[Eu3+]/[Tb3+] phosphor with these characteristics in an LED color filter, a flexible composite prepared by mixing with PDMS showed green, red, and yellow-white emission under a UV-lamp.

Modulating A site compositions of europium(iii)-doped double-perovskite niobate phosphors

Eu3+-activated double-perovskite niobates of A2InNbO6 were synthesized with the modulation of their A site and the polydimethylsiloxane flexible light-emitting films based on the optimized phosphors were implemented for versatile applications.