Crystal structure and photoluminescence investigations of Y3Al5O12:Dy3+ nanocrystalline phosphors for WLEDs

Structural and Luminescent Properties of Dy(III) Doped Ca0.5Bi3P2O10 Nanophosphors for Solid-State Lighting & Latent Fingerprinting Applications

An efficient urea-assisted SC (solution-combustion) approach was used to synthesize a novel series of doped Ca0.5Bi3P2O10: xDy3+ nanophosphors (0.01-0.1 mol). The powdered materials were thoroughly investigated using structural and optical measures. 'Rietveld refinement' investigations found that the produced nanophosphor formed a triclinic system with the P -1 triclinic space group. An EDS (energy-dispersive spectral) study was conducted to determine the corresponding proportions of constituent elements of doped nanophosphors. The TEM (transmission electron microscopy) revealed aggregated particles with a standard size on the nanoscale. The PLE (Photoluminescence excitation) spectrum indicates that the indicated phosphors can be stimulated by NUV (near ultraviolet) illumination sources. The Dy3+-ions undergo transitions from (4F9/2 → 6H15/2 & 4F9/2 → 6H13/2) were recognized as (PL) spectra with an excitation of 353 nm revealed the presence of blue-yellow bands at 481, and 577 nm, correspondingly. Further, PL data was used to determine photometric metrics such as CCT (correlated color-temperature), CC (chromaticity-coordinates (x & y)), and CP (color-purity (%)), supporting their use in solid-state lighting and latent fingerprinting applications.

Investigation on Luminescence Properties of Dy3+ Ions Doped NaBaB9O15 Phosphors for Optoelectronic Applications

A series of Dy3+ ions doped NaBaB9O15 phosphors with different dopant concentration was synthesized by solid state reaction. The phase purity was checked by X-ray diffraction analysis and the functional groups present in as prepared phosphors was investigated with the help of FTIR spectral analysis. Under 386 nm excitation, the photoluminescence spectra exhibit three emission bands around 482 nm, 574 nm and 664 nm due to 4F9/2→6HJ/2 (J = 15, 13, 11) transions respectively. The optimum doping concentration of Dy3+ ions was found to be 5 mol%. The color coordinates are estimated from the emission spectra to check the dominant emission color and the color coordinates of the studied phosphors are fall on white region of CIE 1931 diagram. The decay curve analysis was made to determine the lifetime of excited state of Dy3+ ions and the decay curves are exhibited bi-exponential behavior irrespective of Dy3+ ion concentration. All these measurents are done in room temperature and the results obtained from these studies are discussed in detail to claim their usage in light emitting devices.

Optimizing white light emission in Dy(iii) complexes: impact of energy transfer from mono and bidentate ligands on luminescence

Complexes of dysprosium(iii) ions with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione featuring various mono and bi-dentate neutral ligands have been prepared and thoroughly investigated. The synthesized complexes exhibit an octa-coordinated environment, achieved by stoichiometrically combining organic ligands and Dy(iii) ions. This octa-coordination environment of Dy(iii) ion was confirmed by FT-IR spectroscopy, thermogravimetry and elemental analysis. Near-white light (NWL) is emitted when complexes were exposed to UV radiation, indicating a significant flow of energy from the sensitizing moieties towards the Dy(iii) ion. This NWL emission might have resulted due to a balance between the intensities corresponding to emission peaks at 480 nm (blue) and 575 nm (yellow) in Dy1-Dy3. Emission spectra recorded at different excitation wavelength were utilized to study the tunability of CIE color coordinates. In addition to their high thermal stability, the complexes display bipolar paramagnetic shifts in their NMR spectra. The 4F9/2 → 6H13/2 transition, contributing ∼62% of the total emission, stands out as a promising candidate for laser amplification due to its dominance in the emission spectra. Additionally, NWL emission observed in a solid Dy(iii) complex opens intriguing possibilities for its application in next-generation white-light emitting devices.

Exploring the role of neutral ligands in modulating the photoluminescence of samarium complexes with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione

Four eight-coordinated luminescent samarium complexes of type [Sm(hfpd)3L2] and [Sm(hfpd)3L'] [where hfpd = 1,1,1,5,5,5-Hexafluoro-2,4-pentanedione L = tri-octyl-phosphine oxide (TOPO) and L' = 1,10-phenanthroline (phen), neocuproine (neoc) and bathocuproine (bathoc) were synthesized via a stoichiometrically controlled approach. This allows for precise control over the stoichiometry of the complexes, leading to reproducible properties. This investigation focuses on understanding the impact of secondary ligands on the luminescent properties of these complexes. Infrared (IR) spectra provided information about the molecular structures, whereas 1H and 13C nuclear magnetic resonance (NMR) spectra confirmed these structural details along with the coordination of ligands to trivalent Sm ion. The UV-vis spectra revealed the molar absorption coefficient and absorption bands associated with the hfpd ligand and photoluminescence (PL) spectroscopy demonstrated intense orange-red emission (648 nm relative to 4G5/2 → 6H9/2) from the complexes. The Commission Internationale de l'Éclairage (CIE) triangles indicated that the complexes emitted warm orange red light with color coordinates (x, y) ranging from (0.62, 0.36) to (0.40, 0.27). The investigation of the band gap as well as color parameters confirms the utility of these complexes in displays and LEDs.

Crystal Chemistry and Photoluminescent Aspects of Bright Orange Light Emitting Sm3+- Activated Ba2BiV3O11 Nanomaterials for Advanced Illuminating Applications

In the present system, Sm3+ activated Ba2BiV3O11 nanomaterial series radiating orange-red light was developed via an efficient approach of solution combustion method. The structural examinations using XRD analysis indicate that the sample is crystallized into the monoclinic phase with the P21/a (14) space group. The elemental composition and morphological conduct were studied via energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) respectively. Also, the formation of nanoparticles was confirmed by transmission electron microscopy (TEM). Photoluminescent (PL) examinations reveal the orange-red emission from the developed nanocrystals via documenting the emission spectra, which reveals the peak at 606 nm due to the 4G5/2 → 6H7/2 transition. Further, the decay time, non-radiative rates, quantum efficiency, and band gap of the optimal sample were computed as 1.3263 ms, 219.5 s- 1, 70.88%, and 3.41 eV respectively. Finally, the chromatic parameters including color - coordinates (0.5565, 0.4426), 1975 K color correlated temperature (CCT), and color purity (85.58%) reflected their excellent luminous performance. The above-mentioned outcomes endorsed the relevancy of the developed nanomaterials as a propitious agent in the engineering of advanced illuminating optoelectronic appliances.

Preparation and luminescence properties of Ba2P2O7:Dy3+, Ce3+ phosphors

In this paper, Ba_2-x-yP₂O₇:xDy³⁺,yCe³⁺ phosphors are synthesized by calcining the precursor via chemical co-precipitation. The phase structure, excitation and emission spectra, thermal stability, the chromatic performance of phosphors, and energy transfer from Ce³⁺ to Dy³⁺ are studied and discussed. The results indicate the samples keep a stable crystal structure as a high-temperature σ-Ba₂P₂O₇ phase with two different coordination of Ba²⁺ sites. Ba₂P₂O₇:Dy³⁺ phosphors can be effectively excited by 349 nm n-UV light and emit 485 nm blue light and a relatively stronger yellow light peaking at 575 nm, corresponding to ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 transitions of Dy³⁺, implying that Dy³⁺ mainly occupies the non-inversion symmetric sites. By contrast, Ba₂P₂O₇:Ce³⁺ phosphors exhibit a broadband of excitation peaking at 312 nm, and two symmetrical emission peaks at 336 nm and 359 nm from 5d¹→⁴F_5/2 and 5d¹→⁴F_7/2 transitions of Ce³⁺, showing Ce³⁺ should merely be presumed to occupy Ba1 site. After Dy³⁺ and Ce³⁺ are co-doped, Ba₂P₂O₇:Dy³⁺, Ce³⁺ phosphors exhibit the enhanced characteristic blue and yellow emission of Dy³⁺ with nearly equal intensity under excitation at 323 nm, meaning Ce³⁺ co-doping increases the symmetry of Dy³⁺ site as well as the sensitizer. Simultaneously, energy transfer from Dy³⁺ to Ce³⁺ is found and discussed. The thermal stability of co-doped phosphors was characterized and briefly analyzed. The color coordinates of Ba₂P₂O₇:Dy³⁺ phosphors fall in the yellow-green region near the white light, while the emission moves towards the blue-green region after the Ce³⁺ is co-doped.

Emerging green light emission of Er3+ -activated single phased GdAlO3 phosphors for lighting applications

An erbium ion (Er³⁺ )-activated gadolinium aluminate (GdAlO₃ ) nanophosphor was synthesized by utilizing urea assisted gel-combustion method. The crystal structure along with all other crystal parameters was determined by X-ray diffraction (XRD) patterns. The selected samples are of orthorhombic phase with Pnma space group. The agglomerated particles within nanorange have been confirmed by transmission electron microscopy (TEM) micrographs. Elemental investigation was performed by energy dispersive X-ray spectroscopy (EDX). Photoluminescence excitation (PLE) spectrum reveals a strong excitation band corresponding to the gadolinium ion (Gd³⁺ ) (276 nm) and a band near ultraviolet (UV) absorption for Er³⁺ (377 nm). Strong excitation band of Gd³⁺ was evident for the energy transfer between Gd³⁺ and Er³⁺ ions. All the doped sampled are excited at 377 nm wavelength. The photoluminescence (PL) spectrum exhibits an intense band at 546 nm (⁴ S_3/2  → ⁴ I_15/2 ) which is responsible for the green emission in the processed samples. The color coordinate values define their color in the green region and correlated color temperature (CCT) values affirm their utility as a cold light source.

Luminous LaAlO3 :Dy3+ perovskite nanomaterials: Synthesis, structural and luminescent characteristics for WLEDs

Single-phase perovskite LaAlO₃ :Dy³⁺ phosphor was synthesized via gel-combustion method at 600 °C utilization Hexamethylenetetramine (HMT) as a fuel. Further calcination of the samples was carried out (800 and 1000 °C) to investigate the resultant effect on the crystalline and luminescence behaviour. The crystal structure having cubic unit cell (space group Pm3̅m) was examined via Rietveld refinement using X-ray diffraction (XRD) data. Additionally, Debye-Scherrer's and Williamson-Hall equations were applied to determine other structural features. The particle size and morphology of phosphors were evaluated using Transmission electron microscope (TEM). Diffraction measurements were supported by the various metal-oxygen vibration modes studied with the help of Fourier transform infrared (FTIR) spectroscopy. Energy dispersive X-ray analysis (EDX) verified the chemical composition of synthesized sample. Luminescence spectra of LaAlO₃ :Dy³⁺ phosphors exhibited intense bands for ⁴ F_9/2 → ⁶ H_15/2 (482 nm, bluish region) and ⁴ F_9/2 → ⁶ H_13/2 (574 nm, yellowish region) transitions. Commission Internationale de L'Eclairage (CIE) and Correlated Color Temperature (CCT) data confirmed cool-white emission of samples under UV-excitation. The interesting and advantageous luminescence characteristics of LaAlO₃ :Dy³⁺ phosphors make them potential materials for WLEDs.

Red-emitting β-diketonate Eu(III) Complexes With Substituted 1,10-phenanthroline Derivatives: Optoelectronic and Spectroscopic Analysis

A series of europium diketonate complexes with 1-phenyl-1,3-butanedione (PBD) and 1,10-phenanthroline derivatives were synthesized and explored spectroscopically. Photophysical characteristics of synthesized complexes have been investigated experimentally as well as theoretically. Photoluminescence emission spectra of complexes do not contain any peak of ligand revealing efficient transferal of energy from ligand to Eu³⁺ ion. Presence of peak at 611 nm corresponding to ⁵D₀ → ⁷F₂ transition is responsible for red emanation of ternary europium complexes. Photophysical parameters viz., Judd-Ofelt, quantum efficiency, radiative and non radiative decay rates were also estimated theoretically from LUMPAC software. Geometry optimization of complexes was done via Avogadro software. All synthesized trivalent complexes exhibit red emission which was further sustained by the position of chromaticity coordinates in CIE triangle. These red emanating materials could be utilized in designing electroluminescent display devices.