Orange-red Luminescence Research Articles

Enhancement of persistent luminescence and mechanoluminescence in Pr3+ doped CaAl2Si2O8: Mn for multifunctional applications at wide temperature range

The orange-red phosphor, which combines persistent luminescence and mechanoluminescence, holds significant importance in advanced bioimaging and optical anti-counterfeiting. However, there are relatively few reports on this type of material currently. In this study, doping CaAl2Si2O8: Mn2+ phosphor with Pr3+ ions significantly increases the material's defect density. Under X-ray/UV excitation, the sample displays exceptional orange-red persistent luminescence and superior mechanoluminescence. More importantly, the samples exhibit the above properties in all temperature regions (including low temperature, room temperature (RT) and high temperature). Additionally, the material demonstrates excellent tissue penetration capabilities and dual-mode luminescence (persistent luminescence and mechanoluminescence), highlighting its potential for bioimaging and optical anti-counterfeiting applications.

Multistage dolomitization influenced by the Emeishan large igneous province: Petrographical and geochemical evidence

The formation of large igneous provinces (LIPs) seems to require a series of conditions conducive to massive dolomitization; however, the specific mechanisms remain unclear. Based on petrographic, geochemical and fluid-inclusion microthermometry analyses, this study identifies the types of dolomites in the Maokou Formation (Middle Permian) in the eastern Sichuan Basin. It analyses the related dolomitization fluids and discusses the influencing mechanisms of the Emeishan large igneous provinces (ELIP) on dolomitization at different stages. Three types of dolomite were identified: (1) fabric-retentive, very finely crystalline, planar-s to nonplanar-a dolomite (MD1); (2) fabric-retentive, fine to medium crystalline, planar-s to nonplanar-a dolomite (MD2); and (3) medium to coarsely crystalline, nonplanar (saddle) dolomite (SD). MD1 exhibited dark-red luminescence under cathodoluminescence and rare earth element patterns that are similar to those of lime mudstone, indicating that its dolomitization fluid was medium-salinity Permian seawater. MD2 displayed orange-red luminescence under cathodoluminescence, with a high Ba content (mean: 397.5 ppm) and positive Eu anomalies (mean: 2.34), indicating that its dolomitization fluid was a mixture of shallowly buried seawater and a small amount of external hydrothermal fluid. SD showed red luminescence under cathodoluminescence, with the highest Ba content (mean: 9820.4 ppm) and significant positive Eu anomalies (mean: 3.165), indicating that its dolomitization fluid was mainly ELIP-related hydrothermal fluid with a small amount of residual seawater. Before the ELIP activity, no dolomite occurred in the study area. In the initial stage of ELIP activity, upwelling of the Emeishan mantle plume led to a shift in sedimentary patterns, promoting the occurrence of reflux dolomitization and the formation of MD1. In the intermediate stage of ELIP activity, the activation of basement faults promoted the occurrence of thermal convection dolomitization, resulting in MD2 formation. In the peak stage of ELIP activity, large-scale eruption of Emeishan basalt led to the development of hydrothermal dolomitization, forming SD. This study provides an approach to the investigation of the influences of LIPs on dolomitization processes.

Spectroscopic studies of TeO2-based glasses doped with Sm3+ and its use as an optical temperature sensor

This study reports the synthesis and characterization of glasses in the (100-x)65TeO2-15Li2O-20ZnO + xSm2O3 system doped with Sm2O3, denoted as Sm3+: TLZ glasses, with varying doping concentrations from 0.1, 0.15, 0.2, 0.35, 0.5, and 1 mol%. The structural and optical properties, as well as the temperature dependence of luminescence, were investigated. Excitation at 405nm resulted in strong orange-red luminescence at 566, 600, and 646 nm. The local environment surrounding Sm3+ ions was explored using the intensity ratio of electric and magnetic dipole transitions. The non-radiative energy transfer between neighboring Sm3+ ions was evaluated using the Inokuti-Hirayama model, allowing for the determination of the critical transfer distance. The temperature dependence of luminescence, displayed by Commission Internationale de L’Eclairage (CIE) chromaticity coordinates, exhibited a monotonic change from (0.611, 0.387) at 295 K to (0.605, 0.393) at 479 K. The Sm3+:TLZ glasses doped with 0.15 mol% showed the highest relative thermal sensitivity of 0.10%K-1 at 479 K, suggesting their potential as luminescent thermometers.

Low concentration Sm3+ ions loaded zinc sodium borate glasses for solid state lighting devices

Herein, zinc sodium borate glasses containing samarium ions were fabricated using the traditional melt-quenching approach and explored using several spectroscopic and structural methods. The XRD data corroborated the host glass specimen's non-crystalline nature. Scanning electron microscopy and the energy dispersive X-ray spectroscopy method were utilized to study the morphological and homogenous attributes. The UV–Vis–NIR wavelengths of absorption showed a total of seventeen distinct Sm3+ ion peaks. The three transitions 4G5/2 → 6H9/2, 6H7/2, and 6H5/2 are evident in the PL data at wavelengths of 644, 597, and 561 nm, respectively, in the red, reddish-orange, and greenish-yellow zones. The luminescence intensity of the investigated glass specimens increases up to 0.4 mol% Sm3+ ion content thereafter reducing because of the non-radiative transfer of energy. The estimated JO intensity parameters exhibit a trend of Ω2>Ω4>Ω6. The trend of the assessed radiative parameters also demonstrated that they are sensitive to changes in the glass network. The Futchbauer-Ladenburgh theory was used to compute the emission cross-section of various transitions utilizing the radiative parameters. The 1931 CIE chromaticity coordinates assessments corroborate the reddish-orange luminescence from the fabricated glasses. The outcomes have proven that obtained BNZSmx glasses doped with low concentrations of trivalent samarium ions are well suited for reddish-orange solid-state lighting systems.

One-step synthesis of orange-red emissive carbon dots: photophysical insight into their excitation wavelength-independent and dependent luminescence.

A low-temperature method was developed to synthesize orange-red luminescence phosphor-doped carbon dots (CDs) without complicated purification procedures. These CDs showed excitation wavelength-independent narrow emission (photo-luminescence quantum yield, Φf ∼ 12 to 22%) with single exponential time-resolved decay in weakly polar/non-polar solvents, indicating the presence of one kind of chromophore. In contrast, the same CDs showed excitation wavelength-dependent broad emission (Φf ∼ 1 to 8%) with multi-exponential fluorescence decay in polar solvents. These CDs exhibited poor solubility in polar solvents, resulting in CD aggregates contributed by excitation wavelength-dependent weak luminescence. The CDs embedded in polymethyl methacrylate (PMMA) polymer film displayed bright orange-red fluorescence under UV 365 nm illumination, indicating their potential application in solid-state luminescence. Further, an analytical method was developed for the naked-eye detection of trifluoracetic acid (red emission) and triethylamine (green emission) under UV 365 nm illumination with reversible two switch-mode luminescence. Additionally, this efficient orange-red luminescence of CDs was utilized for possible bioimaging applications with negligible cytotoxicity in 3T3 mouse fibroblast cells.

Comprehension of the photoinduced charge transfer assisted energy transfer in Gd3+-based host sensitized tellurate phosphors for thermal sensing and anticounterfeiting labels.

A series of novel Eu3+-activated Ba2Gd2/3TeO6 (BGT) phosphors were successfully synthesised via a high temperature solid state reaction method. The crystal structure analysis showed that Eu3+-doped Ba2Gd2/3TeO6 double perovskite phosphors possess monoclinic symmetry with space group P21/n. The as-prepared phosphors can be efficiently excited by far-ultraviolet light to generate reddish orange luminescence of around 593 nm corresponding to the 5D0 → 7F1 transitions of Eu3+ ions. Gd3+ acts as a sensitizer for luminescence enhancement. The highest luminescence intensity corresponded to x = 0.11 Eu3+ concentration, and the critical distance was calculated to be 9.61 Å, indicating that multipolar interaction is behind the concentration quenching mechanism. Besides, the optimum concentration Eu3+-activated Ba2Gd2/3TeO6 phosphor exhibited color co-ordinates of (0.63, 0.36), a high color purity of 94.21% and a quantum efficiency of 18%. JO intensity parameters reveal the slight distortion of the crystal field around the activator ion. Notably, the maximum relative sensitivities of the BGT:0.11Eu3+ phosphor were found to be 0.19% K-1 within the temperature range of 300-500 K and 2.07% K-1 within 80-300 K, and it can potentially be used as a promising thermometer in high and low temperature regions, respectively. The luminescent labels based on fluorescent ink and PL chalk demonstrate the potential application of synthesized phosphors in anti-counterfeiting and security labeling.

Controlling the europium oxidation state in diopside through flux concentration.

This paper explores the connection between the H3BO3 flux concentration and the co-existence of Eu2+ and Eu3+ dopants within CaMgSi2O6 crystals (diopside). The samples were synthesised using a solid-state synthesis method under varying atmospheric conditions, including oxidative (air), neutral (N2), and reductive (H2/N2 mixture) environments. Additionally, some materials underwent chemical modification by partially substituting Si4+ with Al3+ ions acting as charge compensation defects stabilizing Eu3+ luminescence. Depending on the specific synthesis conditions, the materials predominantly displayed either the orange-red luminescence of Eu3+ (under oxidising conditions) or the blue luminescence of Eu2+; however, the comprehensive results confirmed the co-existence of Eu3+/Eu2+ luminescence in both cases. This work shows that varying flux concentrations added during synthesis significantly affect the relative strength of Eu2+ and Eu3+ emissions in a manner dependent on the synthesis atmosphere. The emission of Eu2+ increases with a higher flux concentration in materials synthesised under oxidative and neutral atmospheres independent of the chemical modification. In contrast, for materials obtained under a reductive atmosphere, the changes in the Eu3+ emission intensity depended on the presence or absence of Al3+ ions namely the increase of flux increased the Eu3+ intensity in the case of unmodified materials and decreased in the Al-modified ones. All observed effects were qualitatively explained considering the double role of the flux in the studied system, which besides facilitating the diffusion of chemical species during synthesis acts as a charge compensating agent by creating B'Si centres stabilizing Eu3+ emission.

Color tunability studies of samarium ions/silver nanoparticles doped titanosilicate glass matrix

The current study aims at synthesizing a titanosilicate glass composite doped with rare earth/plasmonic nanoparticles using a cost effective and easier method of non-hydrolytic sol gel method. The rare earth employed is samarium ions while the plasmonic nanoparticle used is Silver. For densification samples were annealed at 800 0C and further characterized by FTIR, XRD, TEM. Matrix confirmation is done by FTIR spectroscopic studies which confirm the presence of Si-O-Si, Si-O, and Ti-O-Ti bonds. Both XRD and TEM analysis affirm the presence and morphology of Ag and TiO2 nanoparticles respectively. In the photoluminescence analysis the trivalent samarium ions show strong reddish-orange luminescence in the 550–670 nm range. The major peaks are obtained at 581 nm, 662 nm, 605 nm. Each of the spectra obtained show three prominent characteristic emission bands correlated to the transitions 4G5/2 to 6H5/2, corresponding to 581 nm, 4G5/2 to 6H7/2 corresponding to 605 nm, and 4G5/2 to 6H9/2 corresponding to 662 nm. We successfully plotted the CIE colorimetry diagram and it is observed that the effect of plasmonic nanoparticles can tune the relative emission intensity of rare earth ions in CIE colorimetry. Our study highlights the significance of incorporating the rare earth ions doping with plasmonic nanoparticles in the color tunability studies, exhibiting their broad applications in LED devices.

Enhanced reddish-orange luminescence from Sm3+/Ag co-doped barium zinc borophosphate glasses: Structural and Judd-Ofelt analysis

We report the synthesis and optical response of Sm3+/Ag nanoparticles (NPs) co-doped glasses through melt quenching method. TEM analysis confirmed Ag NP formation, and the diverse functional groups were confirmed through FTIR studies. The Judd-Ofelt (JO) parameters are calculated using JO theory from absorption spectra. The PL spectra were recorded under 402 nm excitation and they show four PL bands in the visible range. The PL spectra are utilized to obtain radiative parameters to claim their utility in visible laser applications. The dominant emission color was obtained by using the CIE color chromaticity diagram. The excited state lifetime values were estimated through decay curve fitting method. All the obtained results are discussed in detail based on Ag NP concentrations.

The investigation of crystal structure, thermodynamic properties, and fluorescence properties of three new rare earth coordination compounds

Three new rare earth coordination compounds [REL3Ph]2(RE = Pr(1), Sm(2)); [ErL3Ph]2·4C2H5OH(3); (L = 2,6-dimethylbenzoate, Ph = o-phenanthroline) were synthesized. The crystal structures of the three compounds were measured by X-ray single-crystal diffraction. From the results, we made out that compounds 1–3 were binuclear structures, and 1D chain-like structures could be formed by hydrogen bonding. The thermal degradation data of the compounds and the three-dimentional infrared cumulative spectra of the gaseous decomposed products were obtained by TG/DSC-FTIR technique, and the thermal degradation patterns were explained. The isobaric molar heat capacity of compounds 1 and 2 in the low-temperature region was obtained by the DSC technique and the thermodynamic parameters were derived. The fluorescence spectrum of compound 2 was determined, showing that it had potential application value in the orange-red luminescence region.

A novel sm3+ activated phosphor powder Ba2LiGa(P2O7)2 with orange–red luminescence and high color purity

A novel sm3+ activated phosphor powder Ba2LiGa(P2O7)2 with orange–red luminescence and high color purity

Perovskite-related structures of Ba2YAlO5 and the β and α phases of Ba6Y2Al4O15 containing AlO4 tetrahedra.

Single crystals of Ba2YAlO5 and of the α and β phases of Ba6Y2Al4O15 suitable for X-ray structure analysis were obtained via grain growth of polycrystalline samples prepared by solid-state reactions. Ba2YAlO5 was found to have a monoclinic crystal structure, with lattice parameters a= 7.2333 (7), b= 6.0254 (5), c= 7.4294 (7) Å and β= 117.249 (3)°, and to belong to the space group P21/m, while α-Ba6Y2Al4O15 was determined to be monoclinic, with a= 5.9019 (2), b= 7.8744 (3), c= 9.6538 (3) Å and β= 107.7940 (10)°, and the space group Pm, and β-Ba6Y2Al4O15 was found to be monoclinic, with a= 7.8310 (2), b= 5.8990 (2), c= 18.3344 (6) Å and β= 91.6065 (11)°, and the space group P2/c. In each of these compounds, BO6 octahedra in ABO3 perovskite-type structures were replaced by AlO4 tetrahedra and YO6 octahedra. Polycrystalline samples in which some Y atoms were replaced with Eu exhibited orange-red luminescence in the range 580-730 nm in response to exposure to radiation having a wavelength of approximately 250 nm.

Investigation of the spectral characteristics of Sm3+ ions in lead borosilicate glass for photonic applications.

Different concentrations of Sm2 O3 -doped lead borosilicate glass were synthesized using a melt-quenching method and their characteristics were analyzed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy absorption, emission, and decay curves. From the XRD patterns, the noncrystalline nature of titled glass was confirmed. The structural groups that existed in the host glass were observed from FTIR spectra. The Judd-Ofelt (JO) intensity parameters and oscillator strengths were derived from the absorption spectra and compared with various reported systems. The excitation luminescence levels of the Sm3+ ion radiative properties were further computed using the JO intensity parameters. Effective bandwidth, emission cross-sections (σe ), and several lasing properties were assessed from emission spectra and compared with other reported glass systems. The decay curves of the 4 G5/2 level of Sm3+ ion were also been measured and examined. Additionally, the colour coordinates of the Commission International de I'Éclairage chromaticity were assessed. The titled glass were suitable for visible reddish orange luminescence devices based on all obtained parameters.

Flexible and luminescent polymer nanocomposite films (YPO4:Pr3+/ polystyrene): Investigation of structural, morphological and photoluminescence properties for solid-state lighting applications

Luminescent polymer films are promising for future optoelectronic devices owing to their ease of synthesis, tunable properties and flexibility. The present work reports on the fabrication of YPO4:Pr3+/polystyrene based flexible and luminescent nanocomposite (NC) films followed by an investigation of their structural, morphological and photoluminescence properties for their potential applications in optical devices. NC films were successfully prepared by direct solution mixing of YPO4: Pr3+ (0.1, 2 at. %) luminescent nanoparticles (NPs) and polystyrene (PS). X-ray diffraction (XRD) analysis of NC films revealed an improvement in crystallinity upon increasing YPO4: Pr3 NPs doping into PS films. The emission spectra of the pure and YPO4:Pr3+/PS NC films under UV excitation at 223 nm showed the same features with a broad emission band in the 280–400 nm region. However, an increase in emission intensity, and absence of interconfigurational emission characteristic of the YPO4: Pr3+ NPs were observed in UV region, due to the strong absorption band of PS in this region. Upon doping, YPO4:Pr3+ NPs were found to reduce their intrinsic luminescence emission from interconfigurational transitions of Pr3+ ions. However, it was dominated by an orange-red luminescence of 1D2→3H4 transition, while, no emission was observed for the PS film owing to its transparency in the visible region. The fluorescence decay times of 1D2→3H4 in the NC films were shorter as compared to those of the original NPs. Chromatic coordinates and correlated color temperature indicated that the YPO4:Pr3+/PS NC films are promising polymer-phosphors for lighting applications.

Orange-red persistent luminescence in Mn2+-Doped Sr3Y2Ge3O12 films for dynamic anti-counterfeiting

The research focus in the field of anti-counterfeiting has shifted toward the secure luminescent label technology, which has gained prominence. The exceptional luminescence properties of persistent luminescence materials are important in the achievement of effective anti-counterfeiting measures. It is in this context that Sr3Y2Ge3O12 can serve as an excellent matrix material. In this study, it is found that Sr3Y2Ge3O12: 4.00% Mn2+ exhibits a luminescence intensity, persistence time, and stability that meet the practical requirements for applications. It is shown that the fabricated persistent luminescence film can be used in anti-counterfeiting applications, thereby, demonstrating the possibility to broaden the application scope of persistent luminescence materials. An emission band centered at 634 nm and a high-energy inflection point at 578 nm are observed in the samples excited at 260 nm. Fluorescence emission at 634 nm is also achieved through X-ray excitation. Through thermoluminescence, photoluminescence, and phosphorescence spectroscopy, a comprehensive investigation of the trap characteristics and inherent mechanisms of the long persistent phosphorescence has been conducted. The novel orange-red Sr3Y2Ge3O12: Mn2+ phosphor is extensively examined.

Orange-red luminescence of samarium-doped bismuth-germanium-borate glass for light-emitting devices.

Samarium (Sm3+ )-doped glass has sparked a rising interest in demonstrating a noticeable emission in the range of 400-700, which is advantageous in solid-state lasers in the visible region, colour displays, undersea communication, and optical memory devices. This study reports the fabrication of Sm3+ -doped bismuth-germanium-borate glasses were established using a standard melt-quenching technique and inspection by absorption, steady-state luminescence, and transient studies. The typical peaks of Sm3+ ions were detected in the visible range under 403 nm excitation. A strong emission band was detected at 599 nm that resembles the 4 G5/2 →6 H7/2 transition of Sm3+ ions for BGBiNYSm0.5 glass. Furthermore, a reddish-orange (coral) luminescence at 646 nm that resembles the 4 G5/2 →6 H9/2 transition was also perceived. The stimulated emission cross-section of 4 G5/2 level for BGBiNYSm0.5 glass was 0.39 × 10-22 cm2 . Lifetime of the 4 G5/2 level was enhanced for the BGBiNYSm0.5 glass and decreased with an increase in active ion concentrations. The lifetime quenching of ions at the metastable state was because of energy transfer among Sm3+ ions by cross-relaxation channels. Commission Internationale de l'Éclairage (CIE) coordinates were evaluated from the emission spectra. Moreover, all the findings recommend these glass as light-emitting materials in the coral region at 599 nm for solid-state lighting applications.

A novel Ca2ScNbO6:Eu3+ phosphor with excellent thermal stability for high color rendering WLED

A series of novel Ca2-xScNbO6:xEu3+ double perovskite phosphors were synthesized by high-temperature solid-state reaction technique. The physical phase, micromorphology, photoluminescence properties, concentration and thermal quenching effect of the phosphors were analyzed. Research shows that: Ca2-xScNbO6:xEu3+ phosphors can be excited by ultraviolet or Blu-ray LED chips and displays a strong orange-red light luminescence at 614 nm. The sample with optimum doping concentrations has a quantum efficiency of 99.13% at room temperature, and the brightness only decays by 7.49% at 433 K. The sample has excellent thermal stability, with a thermal quenching extinction activation energy of 0.497 eV. Finally, the samples are packaged with 395 nm chips together with green and blue phosphors to obtain white LED, that emits bright white light under forward bias currents and have the advantages of lower correlated color temperature (less than 4390 K) and higher color rendering index (higher than 89). The above results indicate that Eu3+ ion-doped Ca2ScNbO6 phosphor can be applied to white LED technology.

Luminescence Characteristics of Green Grossular Garnets

Some light green grossular garnets exhibit orange-red luminescence under long-wave and short-wave ultraviolet light. To characterize their luminescence behavior, we studied seven grossular garnets with typical colors ranging from light yellowish-green to intense green by using photoluminescence (PL), ultraviolet–visible (UV–Vis) spectroscopy, electron paramagnetic resonance (EPR), Electron Probe Microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In the PL spectra of these grossular garnets samples, a broad band exists at about 589 nm and three sharp peaks appear at 697, 702 and 716 nm. The three-dimensional fluorescence spectra reveal two luminescence emissions. They are (1) a broad band near 600 nm; and (2) a series of sharp peaks centered at 697, 702 and 716 nm. In the UV–Vis spectra, two prominent asymmetrical absorption bands near 430 and 605 nm are related to Cr3+ or Cr3+/V3+, and minor absorption peaks at 408 and 419/420 nm are related to Mn2+. EMPA and LA-ICP-MS analysis confirmed the existence of trace elements Ti, V, Cr and Mn. Furthermore, the EPR spectrum excluded the existence of V2+ and V4+ and confirmed the existence of Mn2+, Cr3+ and Fe3+. Regarding V, an interesting phenomenon was reported in which the intensity of luminescence could be suppressed in grossular garnets with higher concentrations of V. These results imply that chromium and manganese are the luminescence activators in grossular garnets, and vanadium is a powerful quencher.

Photoluminescence properties and energy transfer of Sr3Sc(BO3)3: Eu3+, Bi3+ phosphors

A number of orange-red Sr3Sc(BO3)3 phosphors with Eu3+ single-doping and Eu3+, Bi3+ co-doping were successfully made using the high-temperature solid-state method. The morphology and composition of the samples were examined using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), high-angle annular dark field (HAADF), and energy dispersive spectroscopy (EDS). Excitation and emission spectroscopy were used to investigate the characteristics of photoluminescence. In this work, Bi3+ are used as sensitizer to improve the emission intensity of Eu3+. The critical (or optimum) doping concentrations of Eu3+ and Bi3+ in Sr3Sc(BO3)3 were obtained experimentally (single-doping: 15 mol.% Eu3+, co-doping: 15 mol.% Eu3+, 0.3 mol.% Bi3+) to explore the energy transfer from Bi3+ to Eu3+. Under UV (393 nm) excitation, a strong orange-red luminescence corresponding to the 5D0→7F1 transition of Eu3+ can be observed, and a clear energy transfer from Bi3+ to Eu3+ can be discovered in the co-doped Sr3Sc(BO3)3. The energy transfer mechanism, as well as the CIE coordinates and decay lifetimes of a representative sample, are also discussed. The results show that Sr3Sc(BO3)3:Eu3+, Bi3+ is an orange-red phosphor with a higher efficiency under near-UV excitation.

Влияние химического состава пористой матрицы и атмосферы спекания на люминесцентные свойства висмутсодержащих композиционных материалов

The spectral-optical and luminescence properties of bismuth-containing composite materials based on matrices of high-silica porous glasses are investigated. Luminescence spectra, luminescence excitation spectra, infrared transmission spectra (8000–4000 cm-1) depending on the composition of different types of matrices and sintering atmosphere (nitrogen, argon) of bismuth-containing composite materials were examined. It was found that the samples of bismuth-containing composite materials are characterized by UV (λem = 350 nm), blue-green (λem = 410–550 nm) and orange-red (λem = 600–725 nm) luminescence due to the presence of various bismuth active centers. The analysis of the spectra obtained by near-infrared spectroscopy demonstrates the formation of Bi2+ dimers of bismuth and bismuth active centers associated with silicon.