Luminescence Of Ions Research Articles

Enhanced luminescence and high stability in Gd3+-doped CsPbBr3 perovskite quantum dots glasses for X-ray detection

The highly luminescent CsPbBr3 perovskite quantum dots (PQDs) glass has shown great potential for applications in X-ray radiation. In this study, the synthesis, crystallization behavior, structural photoluminescence (PL), and X-ray excited luminescence (XEL) of new scintillation luminescent ion Gd3+-service behavior studies were conducted to evaluate the effectiveness of the Gd3+-doped PQDs glasses as X-ray scintillators. The direct band gap semiconductor property makes it suitable for successful detection of X-ray radiation and allows for efficient absorption and emission of X-ray photons, leading to enhanced scintillation performance. These findings highlight the potential of Gd3+-doped CsPbBr3 PQDs glasses as promising materials for X-ray scintillation applications.

Highly luminescent ultra-thin films with rare earth for plasmonic applications

Amphiphilic complexes with luminescent rare earth metal ions suitable for Lanmuir-Blodgett (LB) deposition have been synthesized. LB monolayers with closely packed Eu complexes deposited directly on silver demonstrate significant far-field emission in contrast to the theoretical predictions of full quenching. Angular radiation and polarization patterns of the electric and magnetic dipole emission of Eu3+ point to a high excitation efficiency of surface plasmon polaritons. Different luminescent behavior of closely packed emitters in comparison to diluted systems is tentatively attributed to the collective state of emitters in LB layers formed via near-field coupling with surface plasmons.

A chemiluminescence method based on Ce-PA-Tb polymer for rapid determination of difloxacin in aquatic products

Ce-PA-Tb polymer with Ce and Tb as metal ion centers was prepared and applied in chemiluminescence (CL) reaction. The structure and property of Ce-PA-Tb were explored. Ce-PA-Tb combines both the oxidant ion (Ce(IV)) and luminescence ion (Tb(III)). Difloxacin can enhance the CL signal of Ce-PA-Tb-SO32- reaction in acidic medium. Under the optimized affecting factors, a CL method for the selective difloxacin determination was established. The CL intensity showed a good linear relationship from 10.0 to 300.0 μg/L (r = 0.9996) with the limit of detection was 1.1 μg/L. The method with the signal response at 0.5 s and completed the CL process within 10 s. The method was used to determine difloxacin in aquatic products, and the recovery rate was in the range of 88.1%–104.0%. The CL method designed Ce-PA-Tb based is demonstrated to be an excellent tool for difloxacin determination in aquatic products.

Enhancing upconversion luminescence of rare earth ions by the activation of the antenna effect in plasmonic cuprous sulfide nanoparticles

To modulate the local electromagnetic field in the upconversion luminescence (UCL) of rare earth ions is one of the most effective ways to improve the luminescence intensity of upconversion nanocrystals (UCNs). Herein, the luminescence intensity of UCNs was increased by 5.8 times by activating the antenna effect of near-infrared plasma in cuprous sulfide nanoparticles. By simulating the local electromagnetic field distribution of the core-shell composites under 980 nm excitation light, the UCL enhancement mechanism of rare earth ions was studied. It showed that the antenna effect of plasmonic cuprous sulfide nanoparticles enhanced the absorption and utilization of excited light by UCNs, and the optical field in the vicinity of the core-shell composites was significantly optimized by inducing the localized surface plasmon resonance coupling between cuprous sulfide nanoparticles. Finally, our results provide a novel way to effectively regulate the local electromagnetic field in the UCL of rare earth ions.

О ВЫХОДАХ ВОЗБУЖДЕНИЯ И ЛЮМИНЕСЦЕНЦИИ ТРЕХВАЛЕНТНЫХ ИОНОВ ЛАНТАНИДОВ ПРИ ОДНОПУЗЫРЬКОВОМ СОНОЛИЗЕ РАСТВОРОВ В СЕРНОЙ КИСЛОТЕ

The light yields of luminescence (Glum) and the yields of excited ion production (yields of excitation, Gext) were measured for the first time for a number of trivalent lanthanide ions (Ln3+) during moving single-bubble sonoluminescence in solutions of 10-2 M Ln3+ in 70% H2SO4. The luminescence yields were determined by comparing the integrated sonoluminescence intensity of the test solution with the radioluminescence intensity of the reference light source, and the excitation yields were found from the relation Gext = Glum/φ, where φ are the photoluminescence quantum yields of Ln3+ ions in the solution, which were also measured experimentally in the work. Determined yields Glum = (0.63, 0.96, 1.8, 5.1, 0.49)´107 photon/100 eV and Gext = (0.066, 1.6, 0.7, 1.5, 0.7)´108 excited ions/100 eV for Ce3+, Eu3+, Gd3+, Tb3+ ions, Dy3+, respectively. It was confirmed that, as previously shown in the case of radiation-excited luminescence of lanthanide ions (Kazakov V.P., Sharipov G.L. Radioluminescence of aqueous solutions. M.: Nauka, 1986. p. 116), transition with a change in the principal quantum number (4f→5d, Ce3+ ion) is an order of magnitude or less lower than the excitation yield in a transition without its change (4f→4f, Eu3+, Tb3+ , and others ions).

Crystal structure and thermally enhanced photoluminescence in Eu(III) coordination polymers self-assembled from p-nitrobenzoic acid

Luminescent thermal quenching is a very troublesome thing for the practical application of luminescent materials, but also is a very common phenomenon. In theory, artificially reducing the number of quenching group around the luminescent lanthanide ion can effectively enhance the luminescence of lanthanide luminescent materials. In this paper, {[Eu2(NBA)6(H2O)4]∙H2O}n [Eu-NBA, NBA = p-nitrobenzoic acid] coordination polymers containing abundant coordination and interstitial water molecules were synthesized via hydrothermal methods. The chemical composition, crystal structures, and thermal stability of Eu-NBA coordination polymers were systemically investigated by Frontier-transfer infrared (FTIR) spectra, single-crystal X-ray diffraction and thermogravimetric analysis. X-ray diffraction analysis results revealed that Eu-NBA coordination polymers were crystallized into one-dimensional (1D) chain structures, where the adjacent Eu3+ ions were linked together by bidentate and/or tetradentate bridging carboxylate groups of the NBA ligands. The temperature-dependent photoluminescence spectra revealed that the shape and intensity of the luminescence spectra strongly depended on the coordination environment around Eu3+, and significant luminescent thermal enhancement was observed. These experimental results provided useful theoretical support for further understanding of the luminescence enhancement mechanism of lanthanide coordination polymers.

Influence of Ga Substitution on the Local Structure and Luminescent Properties of Eu-Doped CaYAlO4 Phosphors

Understanding the local environment of luminescent centers in phosphors serves as a blueprint for designing the luminescent properties of phosphors. Chemical substitution is a general strategy for engineering the local structure around luminescent center ions. In this study, we systematically investigate the luminescent properties of Ga-substituted Eu-doped CaYAlO4 (CYAGO:Eu) phosphors and the local structure of the Eu ions. The Ga substitution at the Al sites leads to a significant enhancement in the electric dipole transition of Eu3+ (5D0 → 7F2). The Judd–Ofelt analysis reveals that Eu3+ ions are substituted for Ca/Y, and the Ga substitution increases the asymmetricity of the local structure around the Eu ions because of the different ionic radii and electronegativities of Al and Ga. In addition, Eu2+ emission is missing regardless of the Ga substitution and post-hydrogen treatments. The present work provides deeper insight into the role of chemical substitution in oxide phosphors.

Impact of luminescent-ion doping on the crystallographic and photo-physical properties of the CaMoO4 nanoparticles.

Luminescent lanthanide (Ln3+ = Pr, Nd, Sm, Eu, and Tb)-ions doped calcium molybdate(CaMoO4) nanoparticles(NPs) were prepared by the polyol wet-chemical route. X-ray diffraction (XRD) pattern of all samples showed the formation of a single-phase scheelite type tetragonal structure with an average crystalline size over 21.6-33.4nm. Thermal stability was evaluated to study the surface-anchored functional groups by weight loss measurement. Fourier transform infrared (FTIR) spectra were recorded to identify the adsorbed functional groups. Aqueous dispersibility and colloidal stability were recorded with the help of the UV/visible absorption spectra. These nanocrystals formed semi-transparent colloidal solutions after being evenly disseminated in aqueous media. The doping of the luminescent ions significantly affects the crystal structure and photoluminescence (PL) properties of the CaMoO4:Ln3+ NPs. In a comparative analysis of the absorption spectra, bandgap, Raman-active modes, and luminescent properties, they were greatly influenced by altering the dopant ion due to the variation in the atomic radius of the element. The doping of smaller atomic radius Ln3+-ions distorts the unit cell, and, subsequently, bond angle/length alters the symmetry of the host crystal. The distorted crystal lattice affects the crystalline, size, lattice parameter, band gap values, Raman active vibrational modes, and luminescent efficiency. The distorted crystal structure of the host lattices facilitates the movement of the oxygen vacancies through charge transfer, resulting in efficiently suppressed emission efficiency.Graphical abstract.

Manipulation of Temperature-Dependent Luminescence Behaviors of Mn4+-Activated Fluoride Phosphors.

In this paper, the giant tunability of thermal behaviors, i.e., from thermal deterioration to substantial growth, is firmly demonstrated for the vibronic luminescence of Mn4+ ions in fluoride phosphors. Such peculiar behavior is uncovered to be associated with the thermal excitation of a low-frequency phonon bath, and a theoretical model involving the excitation-wavelength-dependent populations of vibronic levels and the temperature-dependent nonradiative recombination processes is successfully constructed. Two main governing parameters, namely, the thermal activation energy Ea and the involved average phonon energy ΔE, are thus determined for the distinct thermal behaviors of Mn4+-ion luminescence. This demonstration may pave the way for manipulating the thermal behaviors of vibronic luminescence in solids to some extent.

Concentration quenching mechanism of dysprosium(III) ions in silicate-substituted fluorapatite

Silicon-substituted apatite doped with Dy3+ ions was obtained by using microwave assisted hydrothermal techniques. The general formula of obtained samples is related to Ca10-xDyx(PO4)2(SiO4)4F2, where x = 0.05; 0.1; 0.2; 0.5. The structural, and morphological features of the obtained materials were determined by using XRD (X-ray powder diffraction) and SEM imaging (Scanning Electron Microscopy). The Rietveld refitment was used for estimation of unit-cell parameters. The photoluminescence of the Dy3+ ions was detected and analysed as a function of dopant concentration. The particular attention was focused on the concentration quenching of Dy3+ ion luminescence as well as the critical transfer radius was calculated. The chromaticity diagram, emission colour and correlated colour temperature (CCT) were evaluated.

Hydrothermal synthesis and tunable luminescence of YPO4:Eu2+/Eu3+, Tb3+ nanocrystals

The homogeneous and well crystallized rare earth ions RE3+ (RE = Eu, Tb) doped YPO4 and YPO4·0.8H2O nanocrystals (NCs) are synthesized by a simple hydrothermal route. The samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The results indicate that the pH value of precursor affects the phase composition and surface morphology of the final product. The results of XPS indicate that both Eu2+ and Eu3+ co-exist in YPO4 NCs, implying that the self-reduction from Eu3+ to Eu2+ takes place with the absence of reducing agents, charge compensation reagents and charge carrier trapping processes. In addition, YPO4:Eu and YPO4·0.8H2O:Eu samples exhibit strong and bright blue and red emission. According to PL spectroscopy, the blue emission is originated from host lattice and Eu2+ ion luminescence and red emission from Eu3+. YPO4:Tb, Eu samples can be effectively excited at 355 nm. An energy transfer phenomenon appears between Tb3+ and Eu3+. It is interesting that by changing the concentration of Tb3+, white phosphor from Y0.90PO4:0.04 Tb, 0.06Eu NCs are successfully obtained. Moreover, the Y0.90PO4:0.04 Tb, 0.06Eu has excellent thermal stability. These results indicate that the combination of defect and rare earth luminescence in YPO4:Tb, Eu NCs can produce tunable luminescence color, which may have potential applications in fields such as solid-state lighting and field emission displays.

Early-stage clustering in Tb-doped borosilicate glasses revealed by high-resolution scanning transmission electron microscopy and luminescence properties

Glasses with the base composition 60 SiO2·37 B2O3·3 Na2O (in mol%) were doped with different concentrations of terbium oxide. These glasses show phase separation in borate-rich droplets surrounded by a silicate matrix. By means of scanning transmission electron microscopic analyses including energy dispersive X-ray spectroscopy, structural changes during phase separation are investigated, focusing mainly on the local sites of the luminescent ions. Moreover, phase separation structures of as cast and heat-treated glasses are characterized regarding droplet shape and size, as well as size distribution. The luminescence properties of the phase separated glasses are correlated with their nano- and microstructure. Already in the glass with the lowest Tb3+ concentration, the local environments in which the Tb3+ ions reside in could be identified. This early clustering of the luminescent ions remains undetected in fluorescence lifetime measurements. Only in the time-resolved fluorescence measurement of the glass with the highest Tb3+ concentration, which contains very large Tb-rich agglomerates, an indication of clustering is found. Since clustering of rare earth ions can be detrimental to the performance of an optical material, early detection is beneficial. The studies show that high-resolution transmission electron microscopy can assist with this concern.

Enhanced ∼2.85 μm mid-infrared emission of Na5Lu9F32: Pr3+/Ho3+ single crystal by introducing of non active Gd3+ ions

A series of novel Na5Lu9F32 fluoride single crystals by keeping the concentrations of Ho3+ (0.5 mol%) and Pr3+ (0.1 mol%) fixed and varying the concentrations of Gd3+ ions (i.e., 0, 0.5, 1.0, 1.2, 1.5 mol%) were prepared successfully by a reformative Bridgman technique for application of 2.85 μm mid-infrared. The impact of the non active Gd3+ ion on the crystallographic structure and optical properties of the single crystal were explored by the aid of the X-ray diffraction, Rietveld refinement, spectra of absorption and emission and decay curves of fluorescence. By leading Gd3+ (1.2 mol%) into Ho3+(0.5 mol%)/Pr3+(0.1 mol%) incorporated Na5Lu9F32 single crystal, the emission intensity at ∼ 2.85 μm was fulfilled significantly about two times enhancement. The destruction of [Ho3+-Ho3+] ion quench clusters and release more luminescent ions are in charge of the enhancement of the emission at 2.85 μm by leading Gd3+ into the fluoride single crystal. The maximum emission cross-section, ∼5.2 × 10−20 cm2, at ∼2.85 μm was estimated on the basis of the emission spectra. Thus, the grown Pr3+/Ho3+/Gd3+ incorporated Na5Lu9F32 fluoride single crystals could be an excellent candidate for source of ∼2.85 μm mid-infrared solid-state laser device.

Insight into Eu3+-Doped Phase-Change K3Lu(PO4)2 Phosphate toward Data Encryption.

Adjusting the local coordination environment of lanthanide luminescent ions can modulate their crystal-field splittings and broaden their applications in the relevant optical fields. Here, we introduced Eu3+ ions into the phase-change K3Lu(PO4)2 phosphate and found that the temperature-induced reversible phase transitions of K3Lu(PO4)2 (phase I ⇆ phase II and phase II ⇆ phase III, below room temperature) give rise to an obvious photoluminescence (PL) difference of Eu3+ ions. The Eu3+ emission mainly focused on the 5D0 → 7F1 transition in phase III but manifested comparable 5D0 → 7F1,2 transitions in the two low-temperature phases. On this basis, the change of Eu3+-doped concentration led to the phase evolution in Eu3+:K3Lu(PO4)2, which could stabilize two types of low-temperature polymorphs to the specific temperature by controlling the doping content. Finally, we proposed a feasible information encryption strategy based on the PL modulation of Eu3+:K3Lu(PO4)2 phosphors, which was caused by the temperature hysteresis of the relevant phase transition, exhibiting good stability and reproducibility. Our findings pave an avenue for exploring the optical application of lanthanide-based luminescent materials by introducing phase-change hosts.

The Influence of Optically Active Impurities on the Performance of Phosphors and Scintillators

This paper provides examples of a strategy employed to improve specific properties of phosphors and scintillators which would otherwise have limited their performance in lighting, cathode-ray tubes, and medical imaging technologies. When electron-hole pairs are produced by the exposure to high-energy radiation, the activator ion in the lattice preferentially captures one of the charge carriers. The subsequent capture of the carrier of opposite charge yields the activator ion luminescence. The carrier of the opposite charge can also be diverted to defects in the lattice. The trapping by defects reduces the brightness of phosphors and is responsible for the unwanted afterglow in scintillators. The strategy that is adopted to suppress the trapping by defects is to deliberately introduce an impurity ion that can compete successfully with the defects for the charge carrier. Since the impurity ion traps charge of the opposite sign to the activator ion, we label them as “anti-activators.” While the use of anti-activators gained importance in the field of scintillators in the 1990’s, results on their use for improving brightness of lamp and cathode-ray phosphors were available in the literature of the 1960’s and 1970’s.

Orbital Hybridization and Hypersensitivity of Eu3+ in YXO4 (X=P, As, V)

A comparative study of Eu3+ ion luminescence in YXO4 (X=P, As, V) with the tetragonal zircon structure is conducted in relation to the intensity of the hypersensitivity 5D0 → 7F2 transition. Both the asymmetry ratio, and the Judd-Ofelt Ω2 intensity parameter increases in the order YPO4 < YAsO4 < YVO4. This correlation is interpreted qualitatively in terms of the covalency and polarizability of (XO4)3−, which increases in the order (PO4)3− < (AsO4)3− < (VO4)3−. The trend is supported by the results of electronic band structure calculations of the three compounds which establish the strength of hybridization between the X cation and the oxygen 2p states. The electronic structure of YAsO4 is calculated to probe the covalence of As–O bonding. The increasing oscillator strength of the Eu3+5D0 → 7F2 transition in going from YPO4 to YAsO4 to YVO4 is consistent with the expectation of ligand dipolar polarization model for hypersensitivity which states that the oscillator strength of the 5D0 → 7F2 transition is proportional to the square of the ligand dipolar polarizability. The connection between the mechanism of hypersensitivity and second harmonic generation (SHG) is presented.

Local crystal field-induced tunable mid-infrared luminescence of CsPb1-xErxBr3 perovskite fluoride glasses and applied to the detection of CO2 in hydrogen energy

In recent years, the mid-infrared (MIR) source has become important for a wide range of applications in sensing, spectroscopy, imaging and communications. Due to the unique intra-4f shell transition, the infrared luminescence of rare earth ions has been widely used in infrared light-emitting devices. Despite recent advances with mid-infrared gain platforms, the lack of a tunable mid-infrared luminescence mechanism remains a significant technological challenge. Here, an efficient mechanism for tuning the local crystal field of rare earth ions by modifying the crystal structure of rare earth perovskites is revealed and tunable mid-infrared luminescence of rare earth ions is achieved. Significantly, the local crystal field of Er3+ is tuned by changing the crystal structure of the CsPb1-xErxBr3 rare earth perovskite. The energy level transition (1550 nm: 4I13/2 → 4I15/2 and 2.7 μm: 4I11/2 → 4I13/2) is changed by tuning the asymmetry of the crystal field and the FWHM of the mid-infrared emission is tunable from 80 nm to 130 nm. A convenient, highly accurate device has also been developed that can be used to measure the CO2 concentration in hydrogen energy. The perovskite glass infrared light source has been well adapted to the characteristic infrared absorption peak of CO2. The instrument can monitor the CO2 concentration in real time, avoiding the safety risks associated with the use of electronic instruments in hydrogen energy. These results are expected to open a wide avenue for a new type of tunable mid-infrared luminescence for a wide range of applications.

Boosting the thermometric performance of the Nd3+, Er3+-based luminescence thermometers by sensitization via Cr3+ ions: the role of the host material

The sensitization of the luminescence of lanthanide ions (Ln3+) through codoping with Cr3+ ions enables an increase in the sensitivity of Ln3+-based luminescent thermometers, as well as a significant enhancement of their luminescence intensity. However, achieving predictable thermometric performance in such thermometers necessitates an understanding of the correlation between the host material and thermometric parameters. In this study, we demonstrate the dependence of the relative sensitivity enhancement and thermal quenching temperature on the strength of the crystal field interacting with Cr3+ ions. The versatility of the presented research enables the development of a tool that allows the design of optical temperature sensors with predefined parameters.

Original Na5(Lu1–x–yGdxYy)9F32: Pr3+/Ho3+ Hybrid Single Crystals for Efficient ∼2.9 μm Mid-Infrared Emission

A novel Ho3+/Pr3+/Y3+/Gd3+ multiply doped Na5Lu9F32 mixed single crystal was successfully grown via a modified Bridgman technique. The structure of the mixed crystal was characterized by means of X-ray diffraction and Raman spectra. The impacts of Y3+ and Gd3+ ions on the 2.9 μm emission of Na5Lu9F32 single crystals, which incorporated fixed Ho3+/Pr3+, were investigated systematically with the aid of the optical spectra and decay curves of fluorescence. The 2.9 μm emission intensity (Ho3+: 5I6 → 5I7) was further heightened upon gradually introducing both Y3+ and Gd3+ ions into Ho3+/Pr3+-incorporated single crystals pumped at 640 nm. The brokenness of ionic quenching clusters of [Ho3+–Ho3+] and the release of more luminescent ions are in charge of the augment of emission at 2.9 μm by introducing Gd3+ or Y3+ ions into the Ho3+/Pr3+ codoped single crystals. A value of ∼8.2 × 10–21 cm2 was estimated for the maximum emission cross section at 2.9 μm of the mixed crystal. The processing of energy transfer among Ho3+, Pr3+, Y3+, and Gd3+ ions was investigated, and the energy transfer efficiency for Ho3+: 5I7 → Pr3+: 3F2 was approximately 57.32%. The Na5Lu9F32-doped Ho3+/Pr3+/Y3+/Gd3+ mixed crystals may be a new laser gain medium for 2.9 μm generation because of their special spectral and physicochemical properties.

Multicolor Circularly Polarized Luminescence from Inorganic Crystalline Nanostructures Induced by Atomic Chirality.

Circularly polarized luminescence (CPL) is well-studied in molecular systems but has been rarely reported in pure inorganic nanoscale crystals. Herein, we develop a family of pure inorganic rare-earth nanowires with robust and color-tunable CPL emissions. The chiral rare earth nanowires possess intrinsic atomic chirality with controlled handedness that is guided by the enantiomers with molecular chirality in the synthesis. By varying luminescent ions incorporated in the crystal lattice, color-tunable CPL can be achieved and is thermally robust, preserving emission over 300 °C, distinct from existing CPL-active materials. Moreover, as a proof of concept, we demonstrate that the synthesized nanostructures can be easily dispersed in a polymer matrix to enable transparent and flexible CPL films. This study opens up a promising avenue to design robust and tunable CPL materials helpful to the understanding of inorganic chiral information and capable of further applications in novel optoelectronic devices.