Excitation-Dependent Photoluminescence of BaZrO3:Eu3+ Crystals

The elucidation of local structure, excitation-dependent spectroscopy, and defect engineering in lanthanide ion-doped phosphors was a focal point of research. In this work, we have studied Eu³⁺-doped BaZrO₃ (BZOE) submicron crystals that were synthesized by a molten salt method. The BZOE crystals show orange-red emission tunability under the host and dopant excitations at 279 nm and 395 nm, respectively, and the difference is determined in terms of the asymmetry ratio, Stark splitting, and intensity of the uncommon ⁵D₀ → ⁷F₀ transition. These distinct spectral features remain unaltered under different excitations for the BZOE crystals with Eu³⁺ concentrations of 0-10.0%. The 2.0% Eu³⁺-doped BZOE crystals display the best optical performance in terms of excitation/emission intensity, lifetime, and quantum yield. The X-ray absorption near the edge structure spectral data suggest europium, barium, and zirconium ions to be stabilized in +3, +2, and +4 oxidation states, respectively. The extended X-ray absorption fine structure spectral analysis confirms that, below 2.0% doping, the Eu³⁺ ions occupy the six-coordinated Zr⁴⁺ sites. This work gives complete information about the BZOE phosphor in terms of the dopant oxidation state, the local structure, the excitation-dependent photoluminescence (PL), the concentration-dependent PL, and the origin of PL. Such a complete photophysical analysis opens up a new pathway in perovskite research in the area of phosphors and scintillators with tunable properties.

Luminescence properties of self-activated Ca5 Mg3 Zn(VO4 )6 and Ca5 Mg3 Zn(VO4 )6 :xEu3+ phosphors

Self-activated Ca₅ Mg₃ Zn(VO₄ )₆ and Ca₅ Mg₃ Zn(VO₄ )₆ :xEu³⁺ phosphors were synthesized via a high-temperature solid-state reaction route. The crystalline structure and luminescence properties of the phosphors were analyzed using an X-ray diffractometer and a photoluminescence spectrometer. The explored results indicated that by varying calcination temperature and the raw material ratio of Ca²⁺ /Mg²⁺ /Zn²⁺ , the phosphors could be developed with different phases, crystallinity, and various fluorescence performances. The fluorescence spectrum of Ca₅ Mg₃ Zn(VO₄ )₆ showed a broad emission band over the range 400-650 nm under an excitation wavelength of 330 nm, as well as green light emission. Furthermore, after introduction of Eu³⁺ ions in Eu(VO₄ )₄ , the luminescence intensity of the Eu³⁺ ions greatly increased as the Eu³⁺ ion concentration increased at the 393 nm excitation wavelength, showing green-yellow light emission simultaneously. Therefore, the obtained phosphors could be used as a potential green-yellow-emitting luminescent material in a white light-emitting diode device.

Controlling the luminescence in K2Th(PO4)2:Eu3+ by energy transfer and excitation photon: a multicolor emitting phosphor

This work highlighted green, red, and white light emission from a single K₂Th(PO₄)₂ compound consisting of actinide and an alkali ion through defect, doping, excitation, and energy transfer manipulation.

HDEHP assisted solvothermal synthesis of monodispersed REPO4 (RE = La–Lu, Y) nanocrystals and their photoluminescence properties

In this paper, a novel method is reported for the preparation of spherical REPO₄ particles.

Effect of Molten Salt Synthesis Processing Duration on the Photo- and Radioluminescence of UV-, Visible-, and X-ray-Excitable La2Hf2O7:Eu3+ Nanoparticles

Ln³⁺-ion-doped nanomaterials possess excellent properties because of their high color purity, longer excited state lifetime, narrow emission, and large Stokes shifts. In this work, we studied the correlation between the luminescence properties of La₂Hf₂O₇:Eu³⁺ pyrochlore nanoparticles (NPs) synthesized by a molten salt synthesis (MSS) method at a relatively low temperature and several MSS processing durations (from 1 to 12 h). We synthesized these NPs with different sizes just by changing the MSS processing time without subjecting to high temperature. Raman spectroscopy confirmed the stabilization of the ideal pyrochlore structure of the La₂Hf₂O₇:Eu³⁺ NPs at various MSS processing durations. The synthesized NPs exhibited bright red emission under UV, visible, and X-ray excitations, highlighting their potential applications as a red phosphor and scintillator. As the MSS processing time was increased from 1 to 12 h, a spectral change in the position of the charge transfer state in the La₂Hf₂O₇:Eu³⁺ NPs was observed. The sample processed by the MSS with a duration of 3 h exhibited the highest luminescence intensity, which was attributed to its optimum crystals with least surface defects and less agglomeration. The obtained results strongly and unambiguously indicate the brighter side of this new type of pyrochlore-based NPs in the fast growing field of solid-state lighting and scintillator materials.

Photoluminescence properties of novel Ba2Lu5B5O17:Eu3+ red emitting phosphors with high color purity for near-UV excited white light emitting diodes

A series of new red-emitting Ba₂Lu_4.98−xEu_xLa_0.02B₅O₁₇ (0.1 ≤ x ≤ 1.0) phosphors were synthesized via the high-temperature solid-state reaction method. The phase formation of the as-synthesized Ba₂Lu_4.48Eu_0.5La_0.02B₅O₁₇ phosphor was confirmed by powder X-ray diffraction analysis. It was found that La³⁺ doping resulted in the reduction of LuBO₃ impurities and thus pure phase Ba₂Lu₅B₅O₁₇ was realised. The morphology of Ba₂Lu_4.48Eu_0.5La_0.02B₅O₁₇ phosphors was studied by field emission scanning electron microscopy (FE-SEM). As a function of Eu³⁺ concentration the photoluminescence spectra and decay lifetimes were investigated in detail. Under excitation at 396 nm, a dominant red emission peak located at 616 nm (⁵D₀ → ⁷F₂) indicated that Eu³⁺ ions mainly occupied low symmetry sites with a non-inversion center in Ba₂Lu_4.48Eu_0.5La_0.02B₅O₁₇. The optimal Eu³⁺ ion concentration was found to be x = 0.5 and the critical distance of Eu³⁺ was determined to be 6.55 Å. In addition, the concentration quenching takes place via dipole–dipole interactions. The phosphors exhibited good CIE (Commission International de I'Eclairage) color coordinates (x = 0.643, y = 0.356) situated in the red region and a high color purity of 97.8%. Furthermore, the internal quantum efficiency and the thermal stability of Ba₂Lu_4.48Eu_0.5La_0.02B₅O₁₇ phosphors were also investigated systematically. The results suggest that Ba₂Lu_4.48Eu_0.5La_0.02B₅O₁₇ may be a potential red phosphor for white light-emitting diodes.

Novel Ba₂Lu₅B₅O₁₇:Eu³⁺ red emitting phosphors with high color purity were prepared for near-UV excited white light emitting diodes.

Advances in tailoring luminescent rare-earth mixed inorganic materials

This tutorial review summarizes the recent advances in the synthesis, characterization and luminescence properties of rare-earth mixed inorganic materials.

Energy transfer dynamics and time resolved photoluminescence in BaWO4:Eu3+ nanophosphors synthesized by mechanical activation

Red purity and high quantum efficiency of BaWO₄:Eu³⁺ projects it as a new red phosphor for application in white LEDs.

Eu3+ local site analysis and emission characteristics of novel Nd2Zr2O7:Eu phosphor: insight into the effect of europium concentration on its photoluminescence properties

New Color tunable Nd₂Zr₂O₇:Eu³⁺ (0–5 mol%) phosphor was synthesized using gel-combustion and its photophysical characteristics such as energy transfer, point group symmetry and Judd–Ofelt parameter were investigated using time resolved photoluminescence.