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Color-tunable and upconversion luminescence of Gd2O2S:Er,Tm phosphor: experimental investigations and first-principles calculation
摘要： The Er3+, Tm3+ co-doped gadolinium oxysulfide phosphors were prepared using solid-state reaction in vacuum. The crystal structure, morphology, and photoluminescence characteristics were, respectively, investigated by X-ray diffraction, transmission electron microscope, upconversion luminescence spectra and Commission Internationale de L’Eclairage diagram. Under 980 nm excitation, the quenching concentration of Er3+ was revealed to be 7 mol% with highest luminescence intensity and fluorescence lifetime. The emitting color of Gd2O2S:Er,Tm phosphors can be tuned by adjusting the concentration of Er3+ and Tm3+. First-principles calculation was employed to clarify the luminescence mechanism of the impurities doped in gadolinium oxysulfide host lattice by calculated band structure, density of states and absorption spectrum.
关键词： first-principles calculation,color-tunable,Gd2O2S:Er,upconversion luminescence,Tm
更新于2025-09-04 15:30:14
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Four new luminescent-organic frameworks exhibiting highly sensing of nitroaromatics: an experimental and computational insight
摘要： Four new metal–organic frameworks (MOFs) namely {[Cd(L)(bpp)]·H2O}n (1), {[Zn(L)(bpp)]·H2O}n (2), {[Cd(L)(bpz)]·H2O}n (3), [Zn(L)(bib)(H2O)]n (4), (H2L = 1,4-bis(4-carboxylbenzyl)piperazine acid; bpp =1,3-bis(4-pyridyl)propane; bpz = 3,3′,5,5′-tetramethyl-4,4′-bipyrazole, bib = 1,4-bis(imidazol-1-yl)butane)) have been designed, synthesized and characterized. The MOFs 1 and 2 are isostructural and possess 4-connected dia topology with rare 8-fold interpenetrating network. In 3, the dianionic ligand L and bpz ligands link binuclear Cd(II) centres to generate a 2D layer framework with a double stranded chain. While in 4, the Zn(II) centres are bridged by L and bib ligands to furnish a 2D framework, which further generates a 3D supramolecular structure through the hydrogen bonding interactions formed between coordinated water molecules and carboxylate groups. The MOF 1 have been utilized as a possible luminescent sensor to detect nitroaromatic compounds (NACs). The results indicates that 1 showed good sensitivity towards p-nitrophenol (PNP) in comparison to other NACs by the decline in its luminescent intensity. The detection limit for PNP was found to be extremely low(1.27 ppm in solution) which represents one of the most efficient MOF-based sensors for PNP. The most plausible mechanism associated with sensing have been explained with the aid of theoretical calculations which indicated that a simultaneous electron/energy transfer phenomenon operating between 1 and NACs contributes toward the decline in the luminescence intensity
关键词： Nitroaromatic,Luminescence sensor,MOFs,Theoretical calculation
更新于2025-09-04 15:30:14
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Controllable competitive nanocrystallization of La3+-based fluorides in aluminosilicate glasses and optical spectroscopy
摘要： Glass ceramic has been regarded as an alternative to traditional bulk materials such as single crystal and transparent ceramic. The nucleation/growth behavior of glass ceramic via crystallization is an important topic but is seldom studied so far. In the present work, a series of La3+-based oxyfluoride aluminosilicate glasses are designed to understand their nanocrystallization processes upon heating. Impressively, controllable LaF3, α-NaLaF4 and β-NaLaF4 phase-competitive crystallization in glasses is achieved and structural/spectroscopic characterizations confirm the key role of Al/Si ratio to determine the release of Na+ ions from glass network to participate in crystallization and phase transformation. Furthermore, the developed glass ceramics are evidenced to be ideal hosts for lanthanide dopants (such as Eu3+ and Yb3+/Er3+), which can effectively incorporate into the precipitated fluoride crystal lattices by substituting La3+ ions. As a consequence, incoherent LED-excitable upconverting devices are constructed to demonstrate their promising application as emitting media in display.
关键词： Luminescence,Glass ceramics,NaLaF4,Optical materials,Upconversion
更新于2025-09-04 15:30:14
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Structural and Luminescence Properties of Anthracene- and Biphenyl-Based Lanthanide Bisphosphonate Ester Coordination Polymers
摘要： Coordinative networks containing lanthanide ions attached via phosphonate ester functionalities provide remarkable luminescence properties. On the basis of ditopic phosphonic ester ligands with biphenylene and 9,10-anthracenylene bridges, a series of compounds with formal composition {[M(NO3)3]L}n or {[M(NO3)3]2(L1)3}n (L = C28H40O6P2; L1 = C26H40O6P2) with M = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y have been synthesized, structurally characterized, and the luminescence behavior was explored in the visible and NIR spectral regions, where applicable. In contrast to closely related networks based on biphenyl bisphosphonate esters from previous work, no evidence for ligand-to-metal energy transfer could be observed, despite strong near-infrared emission in some cases. Unique behavior is found for the Eu derivative with the 9,10-anthracenylene bridge, which is nonemissive, showing neither ligand- nor metal-based emission.
关键词： lanthanide,phosphonate ester,luminescence,NIR emission,coordination polymers
更新于2025-09-04 15:30:14
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Multi-Color Luminescent m-LaPO <sub/>4</sub> :Ce/Tb Monospheres of High Efficiency via Topotactic Phase Transition and Elucidation of Energy Interaction
摘要： Monoclinic (m-) structured (La0.96?xCe0.04Tbx)PO4 phosphor monospheres (x = 0?0.12) of excellent dispersion and morphology uniformity were calcined (≥600 °C) from their precipitated precursor spheres (～2.0 μm) of a hexagonal (h-) structure for efficient and multicolor luminescence. The h → m phase transition, driven by dehydration, was originally proposed to proceed in a topotactic manner, which involves displacement of the RE-O polyhedra (RE: rare-earth) along the a/b axis and slight expansion of the {010} and {100} interplanar spacings of the hydrated h-phase to form the {120} and {100} planes of the anhydrous m-phase, respectively. Analysis of the energy process involving the optically active Ce3+ and Tb3+ ions found efficient Ce3+ → Tb3+ energy transfer occurring via electric dipole?quadrupole interaction, whose efficiency reached the highest value of ～44.48% at x = 0.10. The Tb3+ codoped phosphors simultaneously displayed the characteristic emissions of Ce3+ (～313 nm) and Tb3+ (～545 nm) upon exciting the Ce3+ ions with 275 nm UV light, with which the emission color was finely tuned from dark blue to green by increasing the Tb3+ content. Fluorescence decay analysis found decreasing and almost constant lifetime values for the Ce3+ and Tb3+ emissions at a higher Tb3+ content, respectively, and the phosphor presented the highest external quantum efficiency of ～84.67% at x = 0.10. The excellent luminescent performance and morphology uniformity may allow the monospheres to find application in lighting and display technologies.
关键词： LaPO4,Ce/Tb,energy transfer,multicolor luminescence,quantum efficiency,Monoclinic
更新于2025-09-04 15:30:14
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Fluorescence Behavior of Bis(cyanostyryl)pyrrole Derivatives Depending on Substituent Position of Cyano Groups in Solution and in Solid State
摘要： We synthesized a novel fluorophores of distyrylpyrrole derivatives possessing cyano groups at different position on olefin. Their fluorescence properties in solution and solid state were investigated by photoluminescence quantum yield and lifetime measurement, which provided radiative decay constant (kf) and nonradiative decay constant (knr). The derivative with cyano groups at inner position of molecule, inner isomer, shows high fluorescence quantum yield (Φf = 0.43) in solution while another derivative with cyano group at outer position, outer isomer, hardly shows fluorescence (Φf < 0.01) due to the large nonradiative decay (knr > 10 ns?1). Upon formation of single crystal or nanoparticles, these difference were inverted; the quantum yield of outer and inner isomer was enhanced and diminished, respectively. We explained these differences between in solution and solid state by means of analysis of single X-ray structure and computation study.
关键词： solid emission,pyrrole derivatives,substituent effect,Solid-state luminescence enhancement
更新于2025-09-04 15:30:14
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A low temperature approach for photo/cathodoluminescent Gd <sub/>2</sub> O <sub/>2</sub> S:Tb (GOS:Tb) nanophosphors
摘要： Titrating the aqueous solution of equimolar RE(NO3)3 and (NH4)2SO4 with NH4OH to pH~9 at ~4 °C produced an amorphous precursor that yielded phase-pure and well dispersed RE2O2S nanopowder (RE=Gd0.99Tb0.01; GOS:Tb) via a RE2O2SO4 intermediate upon annealing in H2. The powders calcined at the typical temperatures of 700/1200 °C exhibited unimodal size distributions and have the average crystallize sizes of ~17/55 nm, average particle sizes of ~284/420 nm, and specific surface areas of ~14.62/4.53 m2/g (equivalent particle sizes: ~56/180 nm). The 1200 °C product exhibited sharp green luminescence at ~544 nm (FWHM = 2.3 nm; λex = 275 nm), with an absolute quantum yield of ~24.8% and a fluorescence lifetime of ~1.34 ms at room temperature. It was also shown that the powder possesses favorable thermal stability (the activation energy for thermal quenching of luminescence ~0.305 eV) and is stable under electron beam irradiation up to 7 kV and 50 μA. The synthetic technique has the advantages of scalability and favorable dispersion and high chemical/phase purity for GOS powder, which may allow the sintering of scintillation ceramics at lower temperatures.
关键词： low-temperature processing,oxysulfide,GOS,luminescence,nanopowder
更新于2025-09-04 15:30:14
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Confinement of Perovskite‐QDs within a Single MOF Crystal for Significantly Enhanced Multiphoton Excited Luminescence
摘要： The development of the photostable higher-order multiphoton-excited (MPE) upconversion single microcrystalline material is fundamentally and technologically important, but very challenging. Here, up to five-photon excited luminescence in a host–guest metal–organic framework (MOF) and perovskite quantum dot (QD) hybrid single crystal ZJU-28?MAPbBr3 is shown via an in situ growth approach. Such a MOF strategy not only results in a high QD loading concentration, but also significantly diminishes the aggregation-caused quenching (ACQ) effect, provides effective surface passivation, and greatly reduces the contact of the QDs with the external bad atmosphere due to the confinement effect and protection of the framework. These advantages make the resulting ZJU-28?MAPbBr3 single crystals possess high PLQY of ≈51.1%, a high multiphoton action cross-sections that can rival the current highest record (measured in toluene solution), and excellent photostability. These findings liberate the excellent luminescence and nonlinear optical properties of perovskite QDs from the solution system to the solid single-crystal system, which provide a new avenue for the exploitation of high-performance multiphoton excited hybrid single microcrystal for future optoelectronic and micro–nano photonic integration applications.
关键词： single crystals,multiphoton excited luminescence,metal–organic frameworks,perovskite-QDs
更新于2025-09-04 15:30:14
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Dinuclear Cu(I) and Ag(I) pyrazolates supported with tertiary phosphines: Synthesis, structures and photophysical properties
摘要： New copper(I) and silver(I) dinuclear 3,5-bis(trifluoromethyl)pyrazolate compounds were prepared by the reaction of corresponding trinuclear metal complexes with the tertiary phosphines (PPh3, PCy3). In the case of copper(I) trinuclear pyrazolate it was shown that the product structure depends on the reagents ratio: mono- and dinuclear complexes were obtained. All the dinuclear complexes obtained exhibit light emission in the solid state under UV irradiation. Observed photoluminescent behavior was confirmed by the TD-DFT study.
关键词： silver(I) pyrazolates,copper(I) pyrazolates,X-Ray,luminescence,tertiary phosphines
更新于2025-09-04 15:30:14
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Heterometallic Organic Frameworks Built from Trinuclear Indium and Cuprous Halide Clusters: Ligand-Oriented Assemblies and Iodine Adsorption Behavior
摘要： Two novel heterometallic organic frameworks built from trinuclear indium and cuprous halide clusters, [(In3O)2(Cu2I2)3(ina)12(H2O)6](NO3)2·7DMA·10H2O (1) and [NH2(CH3)2][In3(OH)2(H2O)2(ina)8(Cu4I4)2]·5DMA·8H2O (2), where Hina = isonicotinic acid, have been successfully constructed with the orientation of the ina ligand. 1 shows a fascinating highly porous honeycomb-like 3D cationic framework with a trigonal-bipyramid-type cage based on a planar [In3O(CO2)6]+ trimer and a rhombohedral Cu2I2 cluster. Comparably, 2 displays a 3D negative network with irregular hexagonal channels constructed from a [In3(OH)2(CO2)8]? trimer and a cubane-like Cu4I4 cluster. Especially, 1 displays a reversible I2 adsorption/release performance with high adsorption capacity, whose mechanism has been disclosed by theoretical simulation. Also, the green/red emission of 2 stems from iodocuprate centers with quenched indium-centered emission.
关键词： I2 adsorption,cuprous halide clusters,luminescence properties,heterometallic organic frameworks,trinuclear indium
更新于2025-09-04 15:30:14