Tunable Luminescence in Sr2MgSi2O7:Tb3+, Eu3+Phosphors Based on Energy Transfer

Dual-emission CPB@SMSO@SiO2 composites with tunable afterglow through energy transfer

Afterglow materials face limitations in color variety, low luminosity, and stability. Thus, developing materials with adjustable afterglow color, increased photoluminescence (PL) intensity, and enhanced stability is crucial. This paper reports the fabrication of a series of core-shell composites, CPB@SMSO@SiO2, which combine Sr2MgSi2O7: Eu2+, Dy3+ (SMSO) and lead halide perovskite quantum dots (CsPbBr3/CPB PeQDs) through a process involving in-situ growth and hydrolytic coating. The SMSO in the composite can absorb 365 nm UV light and then emit 470 nm light, which can be absorbed by the CsPbBr3 PeQDs, resulting in an overall increase in the PL intensity of the composite. The afterglow color can be turned from green to blue by adjusting the ratio of SMSO and CsPbBr3. Furthermore, the stability of the composites is improved by the SiO2 shell layer formed by hydrolysis of tetramethyl orthosilicate (TMOS). This study presents an opportunity to develop innovative afterglow materials.

Optimizing the Mechanoluminescent Properties of CaZnOS:Tb via Microwave-Assisted Synthesis: A Comparative Study with Conventional Thermal Methods

Recent developments in lighting and display technologies have led to an increased focus on materials and phosphors with high efficiency, chemical stability, and eco-friendliness. Mechanoluminescence (ML) is a promising technology for new lighting devices, specifically in pressure sensors and displays. CaZnOS has been identified as an efficient ML material, with potential applications as a stress sensor. This study focuses on optimizing the mechanoluminescent properties of CaZnOS:Tb through microwave-assisted synthesis. We successfully synthesized CaZnOS doped with Tb3+ using this method and compared it with samples obtained through conventional solid-state methods. We analyzed the material's characteristics using various techniques to investigate their structural, morphological, and optical properties. We then studied the material's mechanoluminescent properties through single impacts with varying energies. Our results show that materials synthesized through microwave methods exhibit similar optical and, primarily, mechanoluminescent properties, making them suitable for use in photonics applications. The comparison of the microwave and conventional solid-state synthesis methods highlights the potential of microwave-assisted methods to optimize the properties of mechanoluminescent materials for practical applications.

Shortwave Ultraviolet Persistent Luminescence of Sr2MgSi2O7: Pr3

Currently, extensive research activities are devoted to developing persistent phosphors which extend beyond the visible range. In some emerging applications, long-lasting emission of high-energy photons is required; however, suitable materials for the shortwave ultraviolet (UV-C) band are extremely limited. This study reports a novel Sr₂MgSi₂O₇ phosphor doped with Pr³⁺ ions, which exhibits UV-C persistent luminescence with maximum intensity at 243 nm. The solubility of Pr³⁺ in the matrix is analysed by X-ray diffraction (XRD) and optimal activator concentration is determined. Optical and structural properties are characterised by photoluminescence (PL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) spectroscopy techniques. The obtained results expand the class of UV-C persistent phosphors and provide novel insights into the mechanisms of persistent luminescence.

Quantum Cutting in KGd(CO3)2:Tb3+ Green Phosphor

Phosphors with a longer excitation wavelength exhibit higher energy conversion efficiency. Herein, quantum cutting KGd(CO₃)₂:Tb³⁺ phosphors excited by middle-wave ultraviolet were synthesized via a hydrothermal method. All the KGd(CO₃)₂:xTb³⁺ phosphors remain in monoclinic structures in a large Tb³⁺ doping range. In the KGd(CO₃)₂ host, ⁶D_3/2 and ⁶I_17/2 of Gd³⁺ were employed for quantum cutting in sensitizing levels. The excited state electrons could easily transfer from Gd³⁺ to Tb³⁺ with high efficiency. There are three efficient excited bands for quantum cutting. The excited wavelengths of 244, 273, and 283 nm correspond to the transition processes of ⁸S_7/2→⁶D_3/2 (Gd³⁺), ⁸S_7/2→⁶I_17/2 (Gd³⁺), and ⁷F₆→⁵F₄ (Tb³⁺), and the maximum quantum yields of KGd(CO₃)₂:Tb³⁺ can reach 163.5, 119, and 143%, respectively. The continuous and efficient excitation band of 273-283 nm can well match the commercial 275 nm LED chip to expand the usage of solid-state light sources. Meanwhile, the phosphor also shows good excitation efficiency at 365 nm in a high Tb³⁺ doping concentration. Therefore, KGd(CO₃)₂:Tb³⁺ is an efficient green-emitting phosphor for ultraviolet-excited solid-state light sources.

Effect of rare earth doping on optical and spectroscopic characteristics of BaZrO3:Eu3+,Tb3+ perovskites

This paper reports structural investigations of rare earth doped BaZrO₃ phosphors synthesized by Solid state reaction technique with varying concentrations of Eu³⁺ and Tb³⁺ from 0 mol% to 2 mol%. The synthesized phosphors show enhanced variable emissions in the visible region corresponding to different hypersensitive electronic transitions of Eu³⁺ and Tb³⁺ ions. With cubic structure confirmed in XRD analysis, the FESEM images show uniform grain connectivity and homogeneity of prepared samples. The TEM micrographs of the synthesized phosphors show agglomerated irregular structures. The synthesized phosphors were also subjected to FTIR, Raman, EDXS analysis along with studies of thermoluminescent and photoluminescent characteristics. On subjecting to 229 nm (UV) excitation, the phosphors show enhanced PL emissions corresponding to 571 nm (⁵D₀-⁷F₀), 591 nm (⁵D₀-⁷F₁), 615 nm (⁵D₀-⁷F₂) and 678 nm (⁵D₀-⁷F₄) hypersensitive transitions of Eu³⁺ ions and emission peaks at 489 nm (⁵D₄-⁷F₆), 539 nm (⁵D₄-⁷F₅), 589 nm (⁵D₄-⁷F₄) and 632 nm (⁵D₄-⁷F₃) accounting for electronic transitions of Tb³⁺ ions respectively. The computed average PL lifetime is 14.014 s. In the TL analysis, the second order of kinetics with the activation energy varying from 5.0 × 10^-1 eV to 6.6 × 10^-1 eV is reported. The maximum TL lifetime is estimated as 19.4985 min in the TL lifetime analysis.