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The advancement of bioimaging and theranostics necessitates the development of highly biocompatible multifunctional agents. Here, we introduce a potential multimodal agent based on nanosized hydroxyapatite (HAp) co-doped with europium(III) and gadolinium(III) (Eu3+ and Gd3+) ions. The study presents a detailed characterization of the HAp:Eu3+/Gd3+ nanoparticles synthesized via the co-precipitation method. The structure and morphology were analyzed using X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. The study of spectroscopic properties (emission, excitation, emission kinetics) as a function of optically active ions was carried out. Moreover, various dopant ratio combinations were studied to optimize the optical and magnetic properties. HAp:Eu3+/Gd3+ demonstrates tunable PL intensity with different concentrations of Eu3+ and Gd3+ ions and increased magnetization with higher doping with Gd3+ ions. Furthermore, co-doping with Gd3+ ions results in an enhancement of Eu3+ emission intensity, rendering HAp:Eu3+/Gd3+ a potentially promising candidate for bioimaging applications. [ABSTRACT FROM AUTHOR]

In this work, three series of micro-sized heterometallic europium-containing terephthalate MOFs, (Eu1-xLnx)2bdc3·nH2O (Ln = La, Gd, Lu), are synthesized via an ultrasound-assisted method in an aqueous medium. La3+ and Gd3+-doped terephthalates are isostructural to Eu2bdc3·4H2O. Lu3+-doped compounds are isostructural to Eu2bdc3·4H2O with Lu contents lower than 95 at.%. The compounds that are isostructural to Lu2bdc3·2.5H2O are formed at higher Lu3+ concentrations for the (Eu1-xLux)2bdc3·nH2O series. All materials consist of micrometer-sized particles. The particle shape is determined by the crystalline phase. All the synthesized samples demonstrate an "antenna" effect: a bright-red emission corresponding to the 5D0-7FJ transitions of Eu3+ ions is observed upon 310 nm excitation into the singlet electronic excited state of terephthalate ions. The fine structure of the emission spectra is determined by the crystalline phase due to the different local symmetries of the Eu3+ ions in the different kinds of crystalline structures. The photoluminescence quantum yield and 5D0 excited state lifetime of Eu3+ are equal to 11 ± 2% and 0.44 ± 0.01 ms, respectively, for the Ln2bdc3·4H2O structures. For the (Eu1-xLux)2bdc3·2.5H2O compounds, significant increases in the photoluminescence quantum yield and 5D0 excited state lifetime of Eu3+ are observed, reaching 23% and 1.62 ms, respectively. [ABSTRACT FROM AUTHOR]

A perovskite material, Barium Zirconate (BZO) doped with 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mol% of Europium (III) were prepared using a solid-state reaction technique. X-ray diffraction (XRD) pattern of BZO doped with 2.0 mol% of Europium was observed. The experimental XRD pattern matched significantly with the standard XRD pattern with the Crystallographic Open Database (COD) card number (96-153-2744) with a figure of merit of 0.89. Photoluminescence emission spectra of the samples prepared exhibited two prominent peaks centred at 592 nm and 612 nm which were attributed to the transitions (5D0→7F2) and (5D0→7F4) respectively. The concentration quenching occurred when the doping concentration was increased after 2.0 mol% of Europium (III). A coordinate (0.58, 0.41) was found in the Colour Chromaticity Diagram (CIE), which falls in orange–red region. The method involved in the calculation of the Judd-Ofelt intensity parameter was briefly described. The ratio R21 = I (5D0→7F2)/I (5D0→7F1) was found as 2.93 which is indicative that the electric dipole transitions are more prominent in comparison to the magnetic dipole transitions. The value of intensity parameters Ω 2 Ω 4 was found as 4.98 × 10−20 cm2 and 8.56 × 10−20 cm2 respectively. [ABSTRACT FROM AUTHOR]

The main objective of this work is to present the enhancement of photoluminescence (PL) and structural properties of Ce3+ and Eu3+ co-doped gadolinium orthosilicate Gd2SiO5 (GSO:Eu, Ce) scintillator elaborated by sol–gel method with different concentration of these rare-earth elements. The samples were characterized by X-ray diffraction, field emission-scanning electron microscopy (FE-SEM) and PL spectroscopy. XRD results confirm the crystallization of samples annealed at 1000°C for 4 h to the monoclinic Gd2SiO5 structure. The crystallographic parameters show that Eu3+/Ce3+ incorporated into Gd2SiO5 changes its structure. FE-SEM micrograph results show rod-shaped particles and EDAX spectra confirm the presence of the main constituent elements of the structure. PL showed that two emission peaks dominate the fluorescence spectra of Eu3+ in Gd2SiO5 and the emission intensity increases relatively with the doping concentration of Ce3+ ions. [ABSTRACT FROM AUTHOR]

This paper investigated the europium-doped lithium sodium potassium borate glasses (LNKBEu). Glass was made using a melt-quenching technique with a range of europium doping concentrations ranging from 0.0 to 5.0 mol%. The absorption spectra showed that photons in the visible light and near infrared ranges were absorbed by the LNKBEu glasses. Photon absorption at 394 nm can excite the mirror to emit a number of photons in the VIS region, such as 590, 613, 652, and 701 nm. The results showed that 3.0 mol% was the optimal concentration of LNKBEu glass. Therefore, 3.0LNKBEu glass was studied using Judd-Ofelt (JO) analysis, which revealed an interesting possibility of its use. This glass is a high power red laser device. [ABSTRACT FROM AUTHOR]

In this study, the phosphorescence properties of Eu3+ and Er3+ co-doped yttria stabilized zirconia (YSZ: Eu3+, Er3+) as a function of oxygen partial pressure and temperature are investigated to explore the possibility of using this phosphor for pressure and temperature measurements at elevated temperature (up to 600 °C). The YSZ: Eu3+, Er3+ phosphors have a fixed Eu3+ concentration (1 mol%) and a varied Er3+ concentration (0.5–5 mol%). The phosphorescence intensity and lifetime of Eu3+ bands are sensitive to both oxygen partial pressure and temperature when temperature exceeds 400 °C. This oxygen/pressure sensitivity is related to the oxygen vacancy-induced non-radiative decay through charge transfer state (CTS), and is inversely correlated with Er3+ concentration. In contrast, the phosphorescence intensity and lifetime of Er3+ bands are temperature-sensitive but oxygen-insensitive, which is related to the dominant oxygen-independent 4S 3/2 → 2H 11/2 transition. Accordingly, two measurement strategies are proposed including an intensity ratio method and a lifetime method. The intensity ratio of the oxygen-sensitive Eu3+ bands and the oxygen-insensitive Er3+ reference bands is capable of 2D pressure measurement using a dual-camera system. But temperature-induced errors exist due to the temperature-sensitivity of intensity ratio. Simultaneous pressure and temperature measurements (point by point) can be achieved utilizing two PMTs that record the lifetimes of Eu3+ and Er3+, respectively. This method can resolve the issue of temperature sensitivity of Eu3+ and accurately correct the temperature-induced errors. The YSZ: Eu, Er phosphors show great potential for applications in high-temperature environment where the existing organic PSPs and TSPs cannot survive. [ABSTRACT FROM AUTHOR]

A series of β‐SiAlON:Eu2+ phosphors were synthesized from single‐source precursors, perhydropolysilazane chemically modified with Al(OCH(CH3)2)3, AlCl3, and EuCl2. The single‐source precursors were converted to β‐SiAlON:Eu2+ phosphors by pyrolysis under flowing N2 or NH3 at 1000°C, followed by heat treatment at 1800°C under an N2 gas pressure at 980 kPa. By varying the molar ratio of the chemical modifiers, β‐SiAlON:Eu2+ with the compositions close to the theoretical ones expressed as Si6−zAlzOz−2yN8−z+2y:yEu2+ were synthesized, where the z values and Eu2+ contents were controlled in the ranges of.44–.78 and.35–1.48 mol%, respectively. The polymer‐derived β‐SiAlON:Eu2+ phosphors exhibited green emission under excitation at 460 nm attributed to the 4f7–4f6(7f3)5d1 transition of dopant Eu2+. High‐angle annular dark‐field‐scanning transmission microscopy analysis confirmed that the doped‐Eu2+ existed interstitially within the channels along the c axis of host β‐SiAlON. Compared with the conventional powder metallurgy route, the polymer‐derived ceramic route in this study offers some advantages in the grain growth of host β‐SiAlON and photoluminescence properties in terms of green emission intensity under excitation at 460 nm, and the highest intensity was achieved for the polymer‐derived β‐SiAlON:Eu2+ with z =.64 and.37 mol% Eu2+. [ABSTRACT FROM AUTHOR]

This research investigates hydrothermally synthesized hydroxyapatite nanoparticles doped with rubidium(I) and europium(III) ions. Investigation focused on establishing the influence of co-doped Eu3+ and Rb+ ions on hydroxyapatite lattice. Therefore, structural, and morphological properties were characterized via using X-ray powder diffraction (XRPD), infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM), as well as transmission electron microscopy (TEM) techniques. Furthermore, this investigation evaluates the impact of various Rb+ ion doping concentrations on the distinct red emission of co-doped Eu3+ ions. Hence, luminescence properties of the obtained materials were evaluated by measuring emission excitation, emission spectra, and luminescence decays. As established by numerous studies, synthetic hydroxyapatite has excellent application in biomedical field, as it is fully biocompatible. Its biocompatible makes it highly useful in the biomedical field as a bone fracture filler or hydroxyapatite coated dental implant. By the incorporation of Eu3+ ions and Rb+ ions we established the impact these co-doped ions have on the biocompatibility of hydroxyapatite powders. Therefore, biocompatibility toward a ram's red blood cells was evaluated to exclude potential cytotoxic features of the synthesized compounds. Additionally, experimental in vitro bioactive properties of hydroxyapatite nanoparticles doped with Rb+ and Eu3+ ions were established using a mouse osteoblast model. These properties are discussed in detail as they contribute to a novel method in regenerative medicine. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of novel luminescent amorphous POSS-based polysilsesquioxanes (PSQs) with Tb3+ and Eu3+ ions directly integrated in the polysilsesquioxane matrix is presented. Two different Tb3+/Eu3+ molar ratios were applied, with the aim of disclosing the relationships between the nature and loading of the ions and the luminescence properties. Particular attention was given to the investigation of site geometry and hydration state of the metal centers in the inorganic framework, and of the effect of the Tb3+ → Eu3+ energy transfer on the overall optical properties of the co-doped materials. The obtained materials were characterized by high photostability and colors of the emitted light ranging from orange to deep red, as a function of both the Tb3+/Eu3+ molar ratio and the chosen excitation wavelength. A good energy transfer was observed, with higher efficiency displayed when donor/sensitizer concentration was lower than the acceptor/activator concentration. The easiness of preparation and the possibility to finely tune the photoluminescence properties make these materials valid candidates for several applications, including bioimaging, sensors, ratiometric luminescence-based thermometers, and optical components in inorganic or hybrid light-emitting devices. [ABSTRACT FROM AUTHOR]

In this paper, Eu/F co-doped bismuth vanadate photocatalysts with different doping ratios were prepared by a hydrothermal method, and their microscopic morphology, crystal structure, light absorption and photocatalytic performance were investigated. Part of the F in the Eu/F co-doped samples might be doped to replace O in the BiVO4 lattice, while Eu3+ ions replaced Bi3+ ions, which led to a difference in the morphology and internal structure. XRD and Raman spectroscopy characterization showed that the crystal structures of the samples were all monoclinic scheelite type, and contained a certain tetragonal scheelite type, and the crystallinity was good. The Eu/F co-doped samples exhibited better photoactivity under UV-Vis light. The recombination rate of the photogenerated carriers in the Eu/F co-doped samples was obviously reduced, but it showed a serious concentration dependence on the doping species. Under visible light irradiation, Eu/F co-doped samples (R = 0.75) had the best degradation effect on methylene blue (MB). In addition, the degradation mechanism of the photocatalyst was also explored. ˙O2− and h+ were the main active species affecting the degradation of MB by Eu/F–BiVO4. [ABSTRACT FROM AUTHOR]

Two new organo-europium complexes (OEuCs) [Eu(tfac)3(TB-Im)] (Eu1) [Eu(hfac)3(TB-Im)] (Eu2) incorporating fluorinated (hexafluoroacetylacetone; Hhfaa) or hemi-fluorinated (trifluoroacetylacetone; Htfac) β-diketones together with the large bite angle N^N ligand (2-(4-thiazolyl)benzimidazole; TB-Im) have been synthesized and characterized. The structure of the complexes has been established by single crystal X-ray diffraction (SC-XRD) analysis and shows that the coordination sphere is composed of a EuO6N2 core (octacoordinated). Continuous shape measures (CShMs) revealed that the geometry around Eu(III) is trigonal dodecahedral with approximate D2d-symmetry. Efficient red emission is observed for both the complexes in solution with a fairly large photoluminescence quantum yield (PLQY (Q LEu) = 39.00–47.00%). Furthermore, by utilizing the experimental photoluminescence (PL) data and theoretical modelling employing density functional theory (DFT) in conjunction with LUMPAC, energy transfer (ET) and back energy transfer rates were calculated, and an ET mechanism for the sensitized PL is proposed and discussed in detail. Finally, the complexes were used as an emitting layer (EML) to fabricate 20 organic light emitting diodes (OLEDs) by varying the doping concentration. Interestingly, both the complex-based OLEDs at 4 wt% doping concentration display white electroluminescence (EL) with the brightness (B) = 100.5–364.1 cd m−2 at very low turn-on voltage (Vturn-on) = 3.9–4.6 V. The overall electroluminescence performance of Eu1 and Eu2 is higher than that of the reported europium based single component white-OLEDs. [ABSTRACT FROM AUTHOR]

To investigate the effect of co-doping on the optical properties of Eu(2+/3+) doped in Ba0.98SiO3:0.02Eu, the series of Ba0.96SiO3:0.02Eu, 0.02R+/3+ (R+ = Li+, K+ or Na+, R3+ = La3+ or Y3+) phosphors were synthesized using a solid-state reaction method. The excitation efficiency due to the charge transfer band (CTB) was enhanced via co-doping of R+ and the emission intensity due to Eu3+ was thus increased by 3.7 times compared with that of the single-doped Ba0.98SiO3:0.02Eu3+. However, the co-doping of R+ does not increase the emission intensity of Eu3+ via the direct 7F0→5L6 excitation of Eu3+, but rather decreases it. On the other hand, the emission intensities due to Eu2+ were decreased via the co-doping of R+ but increased via the co-doping of La3+. The present work reveals that the optical properties of Eu3+ or Eu2+ doped in BaSiO3 depend not on the charge state (+ or 3+) of the co-doped ions, but on the co-doped element itself. [ABSTRACT FROM AUTHOR]

Gallium nitride co-doped with magnesium and europium shows great potential for active layers in red light emitting diode structures due to strong and sharp luminescence emission around 620 nm. In this work, sharp and intense Eu3+ luminescence lines from the excited states of the 5D J (J = 0, 1) multiplets to the ground states of the 7F J (J = 0, 1, 2) multiplets have been analyzed using a C 2 v crystal-field equivalent operator Hamiltonian. A model of Eu centers with the C 2 v symmetry has been proposed to be an Eu3+ complex accompanied by either a pair of nitrogen and gallium vacancies (V N - V Ga) or a pair consisting of a nitrogen vacancy and magnesium impurity (V N - Mg Ga) in the vicinity of the Eu ion based on the crystal-field analysis, the selection rules and the observed polarization of the Eu3+ luminescence lines. Energy transfer from the host to the Eu ions under band-to-band excitation occurs through electron-hole recombination between V N with the electron-like state and V Ga or Mg Ga with the hole-like state; these may be associated with the shallow-trapped or deep-trapped states, respectively, proposed as the energy transfer mechanism in previous literature. • Polarized photoluminescence/cascade-luminescence from ex situ Eu-doped GaN(Mg). • Energy levels/states of 7F 0 ,7F 1 and 7F 2 multiplets of Eu3+ experimentally estimated. • Model of Eu centers in GaN(Mg) with C 2 v (orthorhombic) symmetry proposed. • Eu complex with N/Ga vacancy pair, or a pair consisting of N vacancy and Mg impurity. • Energy transfer GaN.→Eu via recombination between these electron-like/hole-like states [ABSTRACT FROM AUTHOR]

Cadmium selenide films were prepared at different volumes of dopant (Europium) concentration by electrostatic- spray-pyrolysis technique. Optical results reveal low absorption and reflection with a corresponding high transmission in the visible region. Strong blue-shift is observed for the band gap energy in all cases of growth, indicating quantum confinement effect. Scanning electron studies reveal relatively smooth surface with small- sized grains on the surface. XRD confirms the crystalline nature of the films having hexagonal (wurtzite) structure with reduction in crystallinity of the film at increased volume of dopant concentration. EDX analysis confirmed the growth of CdSe:Eu film. [ABSTRACT FROM AUTHOR]

Implementation of more refined structures at the nano to microscale is expected to advance applications in optics and photonics. This work presents the additive manufacturing of 3D luminescent microarchitectures emitting light in the visible range. A tailor‐made organo‐metallic resin suitable for two‐photon lithography is developed, which upon thermal treatment in an oxygen‐rich atmosphere allows the creation of silicon‐free tetragonal (t‐) and monoclinic (m‐) ZrO2. The approach is unique because the tailor‐made Zr‐resin is different from what is achieved in other reported approaches based on sol−gel resins. The Zr‐resin is compatible with the Eu‐rich dopant, a luminescent activator, which enables to tune the optical properties of the ZrO2 structures upon annealing. The emission characteristics of the Eu‐doped ZrO2 microstructures are investigated in detail with cathodoluminescence and compared with the intrinsic optical properties of the ZrO2. The hosted Eu has an orange−red emission showcased using fluorescence microscopy. The presented structuring technology provides a new platform for the future development of 3D luminescent devices. [ABSTRACT FROM AUTHOR]

Undoped Y2Sn2O7 and Eu3+ doped Y2Sn2O7 samples with doping concentrations 7%, 8%, 9%, and 10% are successfully synthesized by the co-precipitation method. A complete structural, morphological, and spectroscopic characterization is carried out. XRD measurements reveal that samples crystallize in the pure single pyrochlore phase and Eu3+ ions occupy sites with D3d symmetry. After mechanical grinding, the average crystallite size is less than 100 nm for all compositions. Optical characterization shows emission from the 5D0 level towards the lower lying 7F0,1,2,3,4 levels. The CIE color coordinates of all the pyrochlore phosphors are very close to those of the ideal red light. For the visualization of latent fingerprints, different surfaces are tested, including difficult ones (wood and ceramic), with excellent results. All three levels of fingerprint ridge patterns are visualized: core (Level 1), bifurcation and termination (Level 2), and sweat pores (Level 3). Moreover, our nano-powders are used to prepare a stable fluorescent ink. [ABSTRACT FROM AUTHOR]

A correlation between piezoelectricity and photoluminescence is investigated for europium doped (Na 0.41 K 0.09 Bi 0.5)TiO 3 ceramic. An optimum piezoelectric and dielectric response is observed for 1.0 at.% Eu doped (Na 0.41 K 0.09 Bi 0.5)TiO 3. For doping concentration higher than 1.0 at.% a gradual fall in the piezoelectric response is observed which is associated to the amphoteric nature of Eu3+ ion. On the contrary, the photoluminescence intensity increases monotonically with the increase in Eu concentration. On application of an electric field, although there is no noticeable shift in the position and shape of the photoluminescence line, a quenching of hypersensitive 5D 0 → 7F 2 transition is observed. The quenching effect is more evident for lower doping concentration (less than 2.0 at.%) of europium. The emergence of irreversible tetragonal phase, after application of the electric field, is attributed to the quenching of 5D 0 → 7F 2 transition. Based on these investigations it is concluded that the piezoelectric and photo-luminescence lack one-to-one correlation. The PL response is associated to the local site symmetry around Eu3+ and it is independent of the development of long-range ordering. [ABSTRACT FROM AUTHOR]

We report on the photoinduced electron transfer in Eu2+ and Sm3+ co-doped CaF 2 nanocrystals prepared by a facile co-precipitation method using CaCl 2 , EuCl 2 , SmCl 3 and NH 4 F. The doping of divalent Eu2+ was realized by employing granular zinc in the CaCl 2 /EuCl 2 solution under nitrogen to reduce Eu3+ → Eu2+. The CaF 2 : x Eu,0.2%Sm nanocrystals were prepared with different Eu concentrations of x = 0, 0.2, 0.5, 1.5, and 2.5%, resulting in an average crystallite size between 54 and 36 ± 1 nm. The maximum luminescence intensities of Eu2+ and Sm2+ were obtained for the x = 0.5% sample. Photoinduced electron transfer and back transfer in the CaF 2 :0.5%Eu,0.2%Sm nanocrystals were measured by detecting the Eu2+ and Sm2+ luminescence, upon exposure to 340 and 310 nm UV LED light. Interestingly, the photoionization of Eu2+ occurred 6 times faster for the sample co-doped with 0.2% Sm. Upon exposure to 340 nm light, a reduction and increase of the Eu2+ and the Sm2+ luminescence were observed, respectively. Subsequent exposure to 310 nm light decreased the Sm2+ luminescence, but the luminescence of Eu2+ kept on being bleached, albeit at a lower rate. Whilst the Sm valence state could be reversibly changed between the trivalent and divalent state by 340 and 310 nm light, the observation that the Eu2+ luminescence did not recover may indicate that a third centre is involved in the photoinduced electron transfer mechanisms. • Nanocrystalline CaF 2 :Eu2+,Sm3+ was prepared by a facile co-precipitation with a reducing step employing Zn. • The co-doping of Sm ions increased the photoionization of Eu2+ → Eu3+ upon exposure to 340 nm light. • The valence state of Sm could reversibly be switched between Sm3+ and Sm2+ by 340 and 310 nm light. • Importantly, whilst Sm2+ was photoionized back to Sm3+, the Eu2+ luminescence signal did not recover upon 310 nm light exposure. [ABSTRACT FROM AUTHOR]

We present a modified version of the Judd-Ofelt theory, which describes the intensities of f-f transitions for trivalent lanthanide ions (Ln3+) in solids. In our model, the properties of the dopant are calculated with well-established atomic-structure techniques, while the influence of the crystal-field potential is described as a perturbation, by three adjustable parameters. Compared to our previous work (Hovhannesyan et al., 2022 [28]), the spin-orbit interaction within the first excited configuration 4f w − 1 5d is described in a perturbative way, whereas it is exactly taken into account in the ground configuration 4f w , using all the eigenvector components of the free-ion levels. Moreover, the wavelength-dependence of the refractive index of the host material is also accounted for. We test the validity of our model on three ions: Eu3+, Nd3+ and Er3+. The results of the extension are satisfactory, we are able to give a physical insight into all the transitions within the ground electronic configuration, and also to reproduce quantitatively experimental absorption oscillator strengths. We also performed calculations of standard JO parameters, and the results are in good agreement with the values reported in the literature. The code used to make the calculations is available on GitLab. • An extension of Judd-Ofelt theory is developed. • The model is based on accurately calculated free-ion properties. • Model is validated on trivalent Eu, Nd and Er. [ABSTRACT FROM AUTHOR]

Mechano-luminescent material can emit light under various external mechanical forces such as pressure, friction, impact and ultrasound. Elastic-luminescent materials have the property that the light signal increases linearly with the increase in stress and has been widely applied. A series of strontium aluminate/strontium calcium samples doped together with europium and dysprosium have been prepared by a high-temperature solid-state method. The effect of strontium/calcium ratio on the crystal structure and luminescence property of the samples have been systematically studied. With the increase of Ca substitution, the crystal field environment around divalent europium ions varies which leads to the changes of the emission peaks. The color presented from samples was tuned from green to blue which offers the possibility of color regulation of mechano-luminescence. Among these samples, the elastic-luminescence of the sample Sr 0.8 Ca 0.2 Al 2 O 4 : Eu2+, Dy3+ shows an excellent performance as the signal increases linearly with the applied pressure, so it has the potential to be used as a pressure sensor. • SrAl 2 O 4 /CaAl 2 O 4 samples doped together with Eu and Dy have been prepared. • The color presented from samples was tuned from green to blue. • Sample Sr 0.8 Ca 0.2 Al 2 O 4 : Eu2+, Dy3+ shows an excellent ML performance up to 8 KN. [ABSTRACT FROM AUTHOR]

Solid solutions of K3Gd(PO4)2:Eu containing 0.1 to 10 mole % of europium(III) were obtained by solid-phase interaction. The obtained micropowders were characterized by X-ray phase analysis, IR, and luminescence spectroscopy. It is shown that doping does not affect the symmetry of the double phosphate framework. All studied samples are characterized by intense red photoluminescence at room temperature, which is associated with the5D0→7F0-4 radiation transitions in Eu3+ ions. The absence of concentration attenuation and color characteristics of the samples indicate the prospects of using the K3Gd0.9Eu0.1(PO4)2 compound as a red phosphor. [ABSTRACT FROM AUTHOR]

The lack of sufficient exploration of lutetium tungstate doped with europium ions has led to significant interest in terms of structure formation and luminescence properties. The series of (Lu 1-x Eu x) 2 W 3 O 12 powders (x = 0.01–1) was synthesized using an improved modified Pechini method (with additional gel treatment) and compared with the previously developed modified Pechini technique. The phase composition of the prepared samples was studied by X-Ray diffraction. XRD analysis verified the orthorhombic structure of the powders (for 1–50 at.% Eu3+) and the monoclinic structure (for 75 and 100 at.% Eu3+). The results also showed the occurrence of phase splitting and formation two Lu 2 W 3 O 12 orthorhombic structures for Eu3+ concentrations above 40 at.% and two Eu 2 W 3 O 12 monoclinic phases above 75 at.% Eu3+ without any impurities. Eu3+ doping concentration significantly affects the structural changes leading to different formations of the shape and size of the particles, the positions of the vibrational states, the luminescence characteristics, and the lifetime of the samples. The optimal doping concentration of Eu3+ is found to be 50 and 75 at.% for host and direct excitation, respectively. The observed 5D 0 lifetime gradually decreases from 0.47 ms to 0.1 ms with the growth of the Eu3+ ions number. • Improved modified Pechini method allows formation single-phase Lu 2 (WO 4) 3 :Eu3+ samples. • Growth of Eu3+ number leads to a consecutive transition from orthorhombic to monoclinic phase. • Eu3+ optimal concentration in Lu 2 W 3 O 12 was 50 at.% and 75 at.% for host and direct excitations. • Lu 2 (WO 4) 3 :Eu3+ samples are promising for use as red phosphors in UV-excited LED devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen-doped carbon quantum dots from banana peel for real-time OTC detection. • Ratiometric fluorescent probe sensors were prepared using N-CQDs with Eu3+ ions. • N-CQDs/Eu3+-based ratiometric sensors detected OTC in pork muscle and swine urine. • Smartphone-assisted N-CQDs/Eu3+-based sensors can be applied in food safety testing. Oxytetracycline (OTC) residues have serious adverse effects on human health. Thus, selective and sensitive field detection methods are needed. Here, we successfully synthesized nitrogen-doped carbon quantum dots (N-CQDs) with good water-solubility, prominent fluorescence (FL), and favorable stability via a one-step hydrothermal method using banana peel as a carbon source and diethylenetriamine as a nitrogen source. We used the N-CQDs to create a ratiometric FL probe by self-assembling them with europium ions (Eu3+), enabling OTC detection. The FL intensity of N-CQDs at 445 nm was quenched due to the inner filter effect, while the FL intensity of Eu3+ at 621 nm markedly increased via the antenna effect upon OTC introduction. The ratiometric FL sensor demonstrated two linear relationships with OTC concentrations, ranging from 0.01 to 5 μg mL−1 and 5 to 25 μg mL−1, with a limit-of-detection of 4.9 ng mL−1 for OTC. Additionally, this platform depicted an apparent color change from blue to purple under a 365 nm ultraviolet–visible lamp, and a visual semi-quantitative analysis of OTC was achieved using a mobile phone application. We successfully implemented this method to detect OTC in pork muscle and swine urine, achieving remarkable recovery results (96.89–103.20%). Therefore, our findings demonstrate the potential of this approach for real-time and semi-quantitative OTC detection. [ABSTRACT FROM AUTHOR]

Eu2+ activated silicate phosphor, Sr 2 SiO 4 :Eu2+ were synthesized by polymerized complex method to investigate the effect of Eu doping on room temperature phases. Firstly, synthesis condition for β phase was optimized and found that β-Sr 2 SiO 4 :Eu2+ phosphors can be obtained at reduction temperature of 1150 °C using HCl, which provide SrCl 2 flux during synthesis process. The characterization for various Eu concentration of Sr 2 SiO 4 :Eu2+ phosphors show that pure β-Sr 2 SiO 4 :Eu2+ phosphors were obtained at 1%, 3% and the samples which are almost in β phase can be achieved until 5%. Temperature dependence of crystal structure and PL properties of Sr 2 SiO 4 :Eu2+ (3%) phosphors were also characterized to investigate the phase transition and thermal hysteresis between β and α′ phase. Phase transition between β ↔ α′ phase was observed from XRD around 60 °C–100 °C and change in PL spectra owing to phase transition was observed around same temperature range. The further analysis show that the thermal hysteresis between β → α′ and α'→ β directions of Sr 2 SiO 4 :Eu2+ (3%) phosphors were about 40 K, which was much larger than the reported thermal hysteresis of undoped Sr 2 SiO 4. Image 1 • Synthesized by polymerized complex method. • Reduction temperature of 1150 °C with flux for β phase. • Eu doping can be achieved by 5% for β phase. • Phase transition between β ↔ α′ phase of Sr 2 SiO 4 :Eu2+ (3%) was observed around 60–100 °C. • Thermal hysteresis of Sr 2 SiO 4 :Eu2+ (3%) was much larger than that of undoped Sr 2 SiO 4. [ABSTRACT FROM AUTHOR]

Tuning the emissive color changes of lanthanide (Ln) complexes is an important and appealing project for promoting the applications of Ln-complexes. A solvothermal reaction of 4-cyano-3-methylbenzoic acid (HL) and Ln(NO3)3·6H2O affords three isostructural Ln-complexes [Eu(L)3(H2O)2]n (1-Ln) (Ln = Eu, Gd and Tb) with one-dimensional chain structures. 1-Eu and 1-Tb show bright red and green emissions with absolute quantum yields of 3.06% and 11.96%, respectively, and the energy transfer was analyzed in detail through combined calculations. Interestingly, a series of heterometallic doped 1-TbxEu1−x coordination polymers were also obtained by mixing different ratios of Eu3+ and Tb3+ ions, which possess continuous luminescent color changes from green to yellow, orange and red. In addition, 1-Eu exhibits high quenching efficiency and low detection limit (∼10−4 M) for the simultaneous sensing of MnO4−, CrO42− and Cr2O72− ions in water. [ABSTRACT FROM AUTHOR]

The structure/property relationships of fluorochlorozirconate glass ceramics as a function of divalent and trivalent europium (Eu) co-doping and thermal processing have been investigated; the influence of doping ratio on the formation of barium chloride (BaCl2) nanocrystals therein was elucidated. X-ray absorption near-edge structure spectroscopy shows that the post-thermal annealing changes the Eu valence of the as-poured glass slightly, but during the melting process Eu3+ is more strongly reduced to Eu2+, in particular, when doped as a chloride instead of fluoride compound. The Eu2+-to-Eu3+ doping ratio also plays a significant role in chemical equilibrium in the melt. X-ray diffraction measurements indicate that a higher Eu2+ fraction leads to a BaCl2 phase transition from hexagonal to orthorhombic structure at a lower temperature. [ABSTRACT FROM AUTHOR]

The present work deals with the investigation of the site-selective symmetries in Eu3+-doped KY 3 F 10 with different crystal phases. Employing time-resolved fluorescence line-narrowing (TRFLN), a study of the luminescent response of the dopant is reported in samples presenting a single δ-phase, a single α-phase, and a mixture of both δ and α. A new, simple, very low time-consuming and high-yield method was developed to obtain nanospheres of the δ-phase. For both crystal phases, the main site symmetry is spectrally corroborated with that expected by the crystallographic substitution position (C 2 v in δ, and C 4 v in α). In addition, the accuracy of the measurements also unveils the presence of significantly distorted Eu3+ ions in the surface of the nanoparticles in all the samples studied, a spectral behavior commonly found in glassy systems. All these findings contribute to the proper understanding of the optical response of luminescent dopants in this and related types of complex fluorides. It is worth highlighting the fact that the huge potential of the unexplored δ-phase is demonstrated, since the site-selective emission of the Eu3+-doped δ-phase is up to 20 times more intense than that of the α-phase. [Display omitted] • KY 3 F 10 phases are very delicate and require precise control in the synthesis. • A new, fast, easy method is developed to obtain nanospheres of the δ-phase. • Site-selective symmetries of Eu3+ in the different crystal phases are revealed. • The finesse of TRFLN underscores the potential of the unexplored δ-phase. • The emission efficiency of the δ-phase is 20 times higher than the α one. [ABSTRACT FROM AUTHOR]

Abstract Atomistic simulations based on lattice energy minimization are used to investigate trivalent and divalent Europium dopant ions in the structure of KMPO 4 (M = Ba and Sr). Interatomic potentials are developed, and the structural properties calculated in this way show good agreement with experimental values. These calculations suggest that Eu3+ and Eu2+ ions are the most energetically provable to be incorporated at divalent (M = Ba and Sr) host sites. It is also predicted that the Eu divalent dopant is charge-compensated by K M ʼ anti-site defects. Four reduction-doping process schemes (open atmosphere, CO, N 2 and H 2 reducing atmosphere) are investigated here, and it is observed that a CO reducing atmosphere is the most effective agent for Eu reduction. The results showed that the preferred host site, charge compensation and schemes for the reduction-doping process for Eu doping ions play important roles in an understanding of the luminescent properties of KMPO 4 (M = Ba and Sr) phosphates. Highlights • The doping of KMPO 4 (M = Ba and Sr) structure with Eu3+ and Eu2+ ions was studied. • The Eu reduction in four atmospheres has been modeled. • The most probable charge compensation mechanisms and the host site preference for doping were identified. • The lowest energy reduction process is predicted and compared with experimental results. [ABSTRACT FROM AUTHOR]

Abstract We studied the effect of europium (Eu) doping on the near band edge emission of ZnO thin films, fabricated by sputtering and high temperatures annealing. The doping concentration of Eu in the ZnO films was varied from 0.01 to 0.62 at.%. Photoluminescence (PL) spectra showed that the films ultra-violet (UV) emission was enhanced very much by high temperature treatment and was stronger for the Eu doped ZnO than that for the un-doped ZnO films after 1100 °C annealing. X-ray diffraction showed the films had hexagonal wurtzite structure, the width of the ZnO (002) plane diffraction peak was sensitive to the anneal temperature and also to the Eu doping concentration, and Zn silicates had formed after the 1100 °C annealing. Scanning electron microscopy showed that the surface morphology of the films became more uneven with increasing Eu concentration. The PL decay spectra inferred that the lifetime of the UV PL was correlated with the size of ZnO nanocrystals in the films. The results support that the intensity of the UV PL is primarily influenced by the crystalline perfection of the films which is also influenced by the Eu doping concentration. [ABSTRACT FROM AUTHOR]

Abstract Single crystal scintillators of RE 2 O 3 :Eu (RE = Lu, Y, Sc) with high (8%) and low (1%) Eu doping concentration were grown by the optical floating zone method. The luminescence and scintillation properties have been investigated and compared thoroughly. Correlated measurements of afterglow curves, photoluminescence excitation and photoluminescence, photoluminescence decay curves and X-ray excitation curves were performed. Lu 2 O 3 :Eu and Y 2 O 3 :Eu present significant afterglow intensity decreasing after high Eu concentration doping. While for the Sc 2 O 3 :Eu, its afterglow intensity even increases slightly. The luminescence efficiencies of high doping concentration samples are weaker than that of the low concentration ones due to the concentration quenching. The integrated X-ray excitation luminescence reveals the scintillation luminescence efficiencies of samples with the high concentration or the low ones both have the following sequence:Lu 2 O 3 :Eu＞Y 2 O 3 :Eu＞Sc 2 O 3 :Eu. Highlights • RE 2 O 3 :Eu (RE = Lu,Y,Sc) single crystal scintillators are grown by optical FZ method. • Sc 2 O 3 :Eu present different afterglow behavior comparing with Lu 2 O 3 :Eu and Y 2 O 3 :Eu. • The relationship between afterglow and Eu(S 6).→Eu(C 2) energy transfer is discussed. [ABSTRACT FROM AUTHOR]

Abstract Er-doped (Bi 0.4 Na 0.4 Sr 0.2)TiO 3 powders were prepared by solid state reactions according to A-site donor (Bi 0.4-x/3 Na 0.4-x/3 Sr 0.2-x/3 Er x)TiO 3 (x = 0.0.015 and 0.02) and B-site acceptor (Bi 0.4 Na 0.4 Sr 0.2)Ti 1-y Er y O 3 (y = 0, 0.015 and 0.02) substitutional doping mechanisms. In both cases, room-temperature X-ray diffraction analyses revealed a decrease of the unit cell volume with increasing Er contents, suggesting A-site occupancy to be thermodynamically more favourable. Over the 25–175 °C temperature range, A-site doped ceramics, in particular x = 0.015, showed enhanced thermal stability of the maximum achievable electric-field induced strain. Importantly, this minor doping level also reduced dielectric loss at high temperature and led to a transition from non-ergodic to ergodic relaxor behaviour. These results may further motivate the study of the impact of other minor dopants in this family of Pb-free piezoceramics. Highlights • Er preferential A-site occupancy in BNT-20ST perovskite-based ceramics. • Er doping leads to a transition from non-ergodic to ergodic relaxor behaviour. • Er enhances electrostrain and its temperature stability in BNT-20ST ceramics. [ABSTRACT FROM AUTHOR]

Highlights • SrZnO 2 has self-excitation luminescence properties. • Excitation properties of SrZnO 2 were regulated by doping Ca2+ ions. • Excitated at 374 nm, Sr 0.85 Ca 0.15 ZnO 2 :Eu3+ obtains a broad emission band. • Tunable red-emitting was realized by doping Ca2+ ions into SrZnO 2 :Eu3+. • Sr 0.85 Ca 0.15 ZnO 2 :Eu3+ obtains the red emission with 90.05% color purity. Abstract A series of Sr 1− x Ca x ZnO 2 :0.02 Eu3+ phosphors have been prepared by solid-state method. The effects of Ca2+ ions on luminescent properties of SrZnO 2 :0.02 Eu3+ have been systematically investigated by X-ray diffraction (XRD) patterns, the photoluminescence excitation and emission spectra, and International Commission on Illumination (CIE) chromaticity diagram. The red-emitting of Eu3+ doped Sr 1− x Ca x ZnO 2 phosphors can be tuned based on the host-sensitized luminescence effect, in which the maximum emission intensity and 90.05% color purity at 396 nm excitation, a broad emission band ranging from 475 to 800 nm at 374 nm excitation have been achieved in the Sr 0.85 Ca 0.15 ZnO 2 :0.02 Eu3+ sample, which demonstrate the occurrence of energy transfer from host to Eu3+ ions. Therefore, Eu3+ doped Sr 1− x Ca x ZnO 2 phosphors will become a promising candidate as a new single-host red-emitting phosphor for white LEDs applications. [ABSTRACT FROM AUTHOR]

Highlights • Thick films were fabricated from europium doped and pure CeO 2 nanoparticles. • The introduction of europium in the CeO 2 lattice does not form secondary phases. • The optimum work temperature for the Eu-doped film was found to be 400 °C. • The Eu-doped film presented higher response to CO than the pure film. • Faster response time to CO was obtained for the Eu-doped film. Abstract Ce 1-(3/4)x Eu x O 2 (x = 0.00 and x = 0.08) thick films were prepared from nanoparticles synthesized by the microwave-assisted hydrothermal route, aiming their application as a carbon monoxide sensing material to prevent deaths caused by this highly toxic gas. XRD analysis revealed that the nanopowders are free from secondary phases and crystallize in the fluorite cubic structure, which is confirmed by Raman spectroscopy. The Eu-doped ceria film presented much higher response (S) values than pure ceria, demonstrating the higher sensitivity of the doped system to carbon monoxide, especially at 400 °C. Electrical measurements under different atmospheres revealed a remarkably fast carbon monoxide response time for the Eu-doped film when compared with the pure sample, proving that the introduction of europium cations in the ceria lattice as dopants has a positive effect on the carbon monoxide sensing properties. [ABSTRACT FROM AUTHOR]

Europium(ii)-doped phosphate cyan@red-emitting phosphors with highly dispersed luminescence centers were developed for the first time by using the deposition–precipitation method. Amazingly, when excited by near-ultraviolet light, the single phosphor generated warm white light with an adjustable correlated colour temperature (4000–2500 K) and high colour-rendering index (Ra∼ 90). [ABSTRACT FROM AUTHOR]

Abstract A series of Eu ions activated in Sr 9-x La 1+x (PO 4) 7-x (SiO 4) x (x = 1, 3, 5, 7) prepared from powder-based precursors have been investigated firstly. The luminescence evolution in response to crystal structure variations was investigated using X-ray diffraction, Rietveld refinement, photoluminescence (PL) and PL excitation spectra, and CIE coordination. As x increased from 1 to 7, the crystal structure changed from whitlockite to apatite, and the ligand bonds between the Eu2+ and O2− ions became shorter. Both crystal structures include two different kinds of Eu sites. The peak positions of the PL bands caused by the Eu2+ ions shifted from 416 nm to 505 nm as x increased with 365 nm excitation. This shift is mainly attributed to the fact that Eu2+ ions prefer higher energy sites in the whitlockite structure and lower energy sites in the apatite structure. The red PL originating from the trivalent europium ions appeared due to the increase in the La3+/Sr2+ ratio with increasing x. Under the various excitation wavelengths, the PL spectra changed tremendously. CIE coordination measurements and 2D PL contour map profiles demonstrated that the phosphor series could be tuned from blue to red by adjusting x, and a tunable phosphor covering full color could be achieved by adjusting the excitation wavelength. Moreover, the PL emission from the x = 1 sample provided an internal quantum efficiency of up to 100%. Graphical abstract Image 1 Highlights • The emission spectra were clarified by Van Uitert equation and crystal field strength equation. • The IQE of the Sr 8 La 2 (PO 4) 6 (SiO4): Eu2+ (for x = 1) phosphor was found to be up to 100%. • By adjusting x with a fixed excitation wavelength, the emission tuned from blue to red. • Fabricated pc-LEDs achieved from cold white to warm white. [ABSTRACT FROM AUTHOR]

Abstract A full-color tunable phosphor by co-substituting Sr2+ and P5+ for La3+ and Si4+ in the single phased oxy-apatite Sr 8-x La 2+x (PO 4) 6-x (SiO 4) x O 2: Eu2+ (SLPSiO; x = 0, 2, 4, 6) phosphor were prepared via solid state reaction method from powder based precursors. The crystal structure information of cell parameters and average bond lengths from luminescence centers to its ligands was analyzed using Rietveld refinement. All the crystal structure of series of phosphors include two different sites of Eu2+, the 7-coordinated Sr1 sites and the 9-coordinated Sr2 sites. The different behaviors of luminescence evolution were due to the Eu2+ ions prefer higher energy sites in the Sr 8 La 2 (PO 4) 6 O 2 (for x = 0) host, but lower energy sites in the Sr 2 La 8 (SiO 4) 6 O 2 host (for x = 6). Also, the red PL originating from the trivalent europium ions appeared due to the increase in the La3+/Sr2+ ratio with increasing x. The blue point (0.2016, 0.1144), bluish white (5000–8300 K CCT), and yellowish white point (2600–3700 K CCT) in the CIE coordination through red colors are included in the 'Fabricated LED' curve, which are suitable for the application of these blends in white-light near UV LEDs. Moreover, the internal quantum efficiency of the x = 0 phosphor approached up to 90%. Highlights • The wide range of the emission spectra of Sr 8-x La 2+x (PO 4) 6-x (SiO 4) x O 2 : Eu2+ (x = 0, 2, 4, 6) were clarified by Van Uitert equation and the crystal field strength equation. • The thermal stability and the IQE (internal quantum efficiency) of the Sr 8 La 2 (PO 4) 6 O 2 : Eu2+ (for x = 0) phosphor was found to be up to 79% and 90%, respectively. • By adjusting x with a fixed excitation wavelength, the emission of this phosphor series can be tuned from blue to red. Moreover, by adjusting the excitation wavelength with a fixed x, a tunable phosphor with full color coverage can be achieved. • Fabricated pc-LEDs using Sr 8-x La 2+x (PO 4) 6-x (SiO 4) x O 2 : Eu2+ (x = 0, 2, 4, 6) phosphor pumped by a near-UV chip achieved from cold white to warm white. [ABSTRACT FROM AUTHOR]

Abstract In this paper we will be presenting JOES (Judd-Ofelt from Emission Spectra), an application software for calculation of the Judd-Ofelt intensity parameters and derived quantities from the emission spectra of Eu3+ doped materials. The program is written to be user friendly and it requires no previous experience in the field of study. This Free and Open-Source program written in JAVA, works on Windows, Linux and MAC OS operating systems. Program has been tested on three europium doped oxides with good luminescent properties: TiO 2 :Eu3+, ZrO 2 :Eu3+ and Nb 2 O 5 :Eu3+. We wish to give to the researchers this theoretical tool which can make the calculations easier, faster and more reliable. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract SrAl 2 O 4 :Eu,Dy is a very efficient long afterglow phosphor with wide range of possible applications. The luminescence properties and the possible luminescence mechanism of this material have been studied extensively, but there is almost no information available about the undoped material. Therefore, this article deals with the luminescence and thermally stimulated luminescence of an undoped SrAl 2 O 4 , revealing the possible defects that might be involved in the creation of the long afterglow in doped material. We conclude that undoped material exhibits some luminescence under X-ray irradiation in low temperature; close to room temperatures luminescence is almost fully thermally quenched in comparison to low temperatures. We can observe F and F 2 center luminescence as well as trace metal luminescence in the emission spectrum. TSL glow curve yields the peaks that are close to those observed in material with Eu and Dy doping; therefore these peaks are clearly related to intrinsic defects. The peak at around 400 K, that is shifting with rare earth doping, might be due to dopant interaction with intrinsic defects. Highlights • We report a clearly distinguishable luminiscence of undoped SrAl 2 O 4 material under X-Ray excitation in low temperatures. • The TSL peaks of undoped material are present also in the doped materials. • Defects in the undoped material also appear in the doped material these defects might be stimulating the Eu3+ ion incorporation. [ABSTRACT FROM AUTHOR]

Abstract The present study reports the insertion of europium ions into the network of lithium lanthanum titanate, La 0.5 Li 0.5 TiO 3 , powders. The materials were prepared efficiently via the Pechini method and were characterized using thermogravimetric analyses, X-ray diffraction, high-resolution electron microscopy and photoluminescence spectroscopy. The results obtained demonstrate the high structural disorder of La 0.5 Li 0.5 TiO 3 (LLTO) as well as the different environments noticed by Eu3+ ions in the La 0.5 Li 0.5 TiO 3 host lattice. Our results are essentially important once they unfold a better understanding of the complex nature of La 0.5 Li 0.5 TiO 3 compounds structure. [ABSTRACT FROM AUTHOR]

Abstract In this work, a new Eu and Tb co-doped luminescent compound based on MOF-5, [Zn 4 O(BDC) 3 ], (named as compound 1) was successfully synthesized. The structure and morphology characterizations demonstrate that the initial framework of MOF-5 is retained well after co-doping Eu and Tb. The systematic investigations of photoluminescence behaviors reveal that the heat-treated compound 1 (called as compound 1a) can be utilized as a multi-channel readout luminescent thermometer in emission intensity ratio, decay time ratio, and luminescence color. It simultaneously exhibits the excellent repetitiveness and reversibility under high temperature region from 303 to 473 K. The relative sensitivity of 1.8%/K at 473 K is much higher than the best one of 1.19%/K previously reported for the mixed-lanthanide MOF Tb 0.8 Eu 0.2 BPDA. Until now, such a ratiometric luminescent thermometer with a high sensitivity at the temperature as high as 473 K has been rarely explored. [ABSTRACT FROM AUTHOR]

Abstract Eu3+ doped transparent glass ceramics (GCs) are obtained via melt- quenching technique and subsequent heating. The structure and morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD and SEM results showed that tetragonal barium molybdate (BaMoO 4) crystals are precipitated in the glass matrix. The excitation spectrum of BaMoO 4 :Eu3+ GCs are composed of Eu3+ ions characteristic excitation peaks. The emission spectra of BaMoO 4 :Eu3+ GCs consists of several sharp emission bands center at 592 nm, 615 nm, 653 nm and 702 nm, respectively. Among them, the strongest one was located at 615 nm due to 5D 0 → 7F 2 transition of Eu3+ generating bright red light. The quantum efficiency of BaMoO 4 :Eu3+ GC is 46.3%, and the fluorescence lifetime is 2.0716 ms, when the Eu3+ ions doping concentration is 0.7 mol%.The results show that Eu3+ doped BaMoO 4 glass ceramics exhibit a potential to act as a kind of red phosphor for white light-emitting diodes (W-LEDs). Highlights • BaMoO 4 :Eu3+ transparent glass ceramics have been prepared. • The optimum doping amount of Eu3+ ion concentration is 0.7 mol%. • Eu3+ doped BaMoO 4 glass ceramics have a strong red emission. • Fluorescence lifetime is calculated. • The quantum efficiency is up to 46.3%. [ABSTRACT FROM AUTHOR]

Abstract In this work, radioluminescence, low temperature thermoluminescence, and light yield of ZnWO 4 , ZnWO 4 :Ca, and ZnWO 4 :Ca, Eu single crystals is reported. It is shown that although the single doping with Ca improves, in a limited scope, the scintillation properties of the studied material, it is not the case with the double doping with Ca and Eu. The values of light yield and energy resolution of the investigated ZnWO 4 :Ca, Eu samples are clearly worse compared to either ZnWO 4 or ZnWO 4 :Ca. The X-ray excited spectra of all the crystals, dominated by the intrinsic luminescence, unveil a strong decrease of intensity from 10 to 350 K; the addition of Eu does not improve this property. Furthermore, the presence of Eu strongly influences the low temperature glow curves, i. a. by introducing a distinct peak close to 150 K. Highlights • ZnWO 4 , ZnWO 4 :Ca and ZnWO 4 :Ca, Eu crystals have been grown by the Czochralski method. • Pulse height, radio- and thermoluminescence measurements have been performed. • Ca-doping hardly improves the scintillation properties, while Eu-doping deteriorates. • Low temperature glow curves have been decomposited and trap parameters derived. [ABSTRACT FROM AUTHOR]

Glass sample of the composition: 10SrO-90TeO 2 was prepared by melt-quenching technique and found to contain triangular, rectangular, and spherical shaped micro-inclusions of the average size ∼803 μm in the glassy matrix. The inclusions grow to an average size of ∼1347 μm and assume flower-like morphology upon adding 1 mol% Eu 2 O 3 in the 10SrO-90TeO 2 sample. X-ray diffraction studies showed that the micro-inclusions exhibit sharp peaks, but their Raman spectra have broad phonon bands that are indistinguishable or very similar to that of the glassy matrix phase. The addition of 10 mol% B 2 O 3 in the samples inhibits the growth of inclusions of anti-glass phases and forms purely amorphous samples. B 2 O 3 significantly enhances the photoluminescence properties of Eu 3+ doped samples. Furthermore, B 2 O 3 converts the four-fold co-ordinated Te-O structural units into three-fold co-ordinated Te-O units. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the effect of host cations on the local structure around the dopant site of materials from the xenotime family is systematically studied on the molecular level. A series of six Eu3+‐doped xenotime‐type single crystals (Tb, Y, Ho, Er, Yb, and LuPO4) have been grown and spectroscopically analyzed by using polarization‐dependent laser‐induced luminescence spectroscopy (p‐TRLFS). Our results demonstrate that the structural disorder changes in a non‐linear manner with a structural break between Yb3+ and Lu3+. Despite adopting identical crystal structures, the solid solutions of these materials vary significantly, and differ from monazite solid solutions. Similar Eu3+ incorporation behavior with a strongly distorted dopant site is found for the early members of the xenotime family, whereas LuPO4 with the largest host versus dopant radii mismatch is anomalous in that it contains the most symmetrical lattice site. This goes along with a significantly stronger crystal field, indicating a shorter Eu−O bond length, as well as a strong vibronic coupling to external translational lattice vibrations. The p‐TRLFS analysis confirms the breakdown of the crystallographic site symmetry from D2d to C1 in YPO4, whereas a small distortion of the crystallographic site in LuPO4 results in an S4 point symmetry for the Eu3+ cation. The lattice with the smallest cation host site is no longer sufficiently flexible to make room for Eu3+ and instead “forces” the guest ion to occupy a less distorted Lu3+ site. [ABSTRACT FROM AUTHOR]

This paper reports the first attempt at the synthesis of single phosphors of europium (Eu3+) and dysprosium (Dy3+) co-doped hydroxyapatite (HA)/β-tricalcium phosphate (TCP) nanostructures providing strong red and yellow luminescence depending on annealing temperature and holding time. The morphology of the phosphors was observed to have a nanowire structure. The photoluminescence (PL) intensity of the phosphors increases with annealing temperature and time. The luminescent phosphors also showed the typical luminescence of Eu3+ centered at 610 nm and Dy3+ centered at 572 nm, which was more efficient for the annealed Eu3+/Dy3+ co-doped HA/TCP phosphors than for as-synthesized ones. These results suggest that the Eu3+ and Dy3+ co-doped HA/TCP nanostructures can find potential application in plant cultivation as environment friendly phosphors. [ABSTRACT FROM AUTHOR]

Europium-doped hydroxyapatite has attracted considerable scientific attention to smart drug delivery scaffold applications because of its biocompatible and traceable luminescence features. In this sense, to investigated the europium incorporation mechanism and photoluminescence properties in the presence of surfactant organic molecules the europium doped-hydroxyapatite samples were synthesized via co-precipitation with hexadecyl trimethylammonium bromide (CTAB) micelles mediated approach. Results of the X-ray absorption spectroscopy techniques (XANES and EXAFS) showed that Eu 3+ ions were incorporated preferentially at the Ca (1) site with local charge compensating via oxygen interstitial ion for samples calcined under air at 450 °C/4 h °C. Europium(III) luminescence analysis suggested that Ca site symmetry became distorted in CTAB medium. [ABSTRACT FROM AUTHOR]

Computational and experimental methods are employed to study the optical properties of Dy-doped BaAl 2 O 4 matrix. Atomistic modelling is used to make predictions of Dy doping sites and charge compensation schemes. The symmetry predicts from atomistic modeling was used to calculate crystal field parameters and to obtain the energies of the electronic transitions of the Dy 3+ ion. Dy-doped BaAl 2 O 4 was prepared via a sol-gel proteic technique. The optical properties were studied using X-ray excited optical luminescence (XEOL) measurements. The X-ray absorption near-edge structure (XANES) at the Ba and Eu L III -edges exhibits typical absorption spectra. The area under the XEOL spectra increases as the photon energy increases in the region around the Ba and Dy L III -edges. The XEOL spectra showed typical Dy lines. Experimental and calculated values for the transition energies are compared. Computational and experimental methods are employed to study of Dy-doped BaAl 2 O 4 matrix. Atomistic modelling is used to make predictions of Dy doping sites. The optical properties were studied using XEOL measurements. [ABSTRACT FROM AUTHOR]

Europium (Eu 3+ )-doped oxyfluorosiliacte (SALfSfEu: SiO 2 + Al 2 O 3 + LiF + SrF 2 + Eu 2 O 3 ) glasses have been fabricated by usual melt-quenching technique. These glasses were characterized through optical absorption, excitation, emission and decay curve analysis. The Judd-Ofelt (JO) parameters have been evaluated from the refractive index and luminescence spectrum of the 1.0 mol% Eu 3+ -doped glass. The quantitative radiative properties including branching ratio, radiative lifetime and stimulated emission cross-sections of the fluorescent levels were predicted by using the JO parameters. Luminescence intensity increases as for as 0.5 mol% and then decreases with further increasing Eu 3+ ion concentration. Photoluminescence quantum yield found to be as high as 74% for 0.05 mol% of Eu 3+ ion concentration and decreased by increasing concentration. Luminescence intensity ratio is found to be 3.17 for 1.0 mol% Eu 3+ -doped SALfSfEu1.0 glass which suggest that the occupation of high degree of symmetry by the Eu 3+ ions. Fluorescent decay curves of the emitting level exhibit an exponential behaviour. Lifetime of 5 D 0 → 7 F 2 transition was decreased slightly with increasing Eu 3+ ion concentration, however, not significant for 5 D 1 → 7 F 1 transition. Luminescence properties reveal that the red emission at 612 nm found to be suitable for developing the lasers and display devices in the visible region. [ABSTRACT FROM AUTHOR]

Abstract: γ‐aluminum oxynitride (γ‐AlON) with spinel structure has attracted much attention for structural and functional application. γ‐AlON powders were successfully prepared by direct nitridation method of Al/Al(OH)3 starting mixture in ammonia and then calcined at high temperature. XRD, SEM, TEM, EDX, and photoluminescence were conducted to investigate the detail procedure and the optical properties of AlON: xEu phosphors. Nitrogen was introduced by the nitridation of metallic aluminum, appropriate Al amount and nitridation condition was necessary to obtain phase pure γ‐AlON. The as‐prepared AlON powders exhibited multifaceted grain morphology with fine particle size (1‐5 μm). Eu2O3 activator was reduced and transformed to EuAl12O19 by reaction with alumina, which remained in the product when x > 0.25%. Under 331 nm excitation, AlON: xEu phosphors exhibited emission bands of 475 and 410 nm. 475 nm band reached a plateau at x = 0.25% due to the solubility of Eu2+ ion in AlON, whereas 410 nm band showed a linear increase in intensity with Eu2+ doping amount, which was believed to be the contribution of EuAl12O19. The present approach combination of direct nitridation in ammonia and postcalcination process showed potential application for AlON ceramic and AlON phosphors. [ABSTRACT FROM AUTHOR]

Acetylacetonate (acac) passivated and europium incorporated ZnGa 2 O 4 nanocrystals (ZGO:Eu NCs) were successfully prepared via a facile one-step non-injection process in oleylamine at a relatively low reaction temperature of 300 °C under N 2 ambient. The resultant ZGO:Eu NCs exhibited a well-dispersed morphology with an average particle size of 4 nm. The enhanced and broad absorption band from 250 to 450 nm is attributed to the synergistic effect between the acac as an antenna and the coexistence of Eu 3+ and Eu 2+ . Under 405 nm excitation, a full spectrum emission covering from 400 to 720 nm was observed. The sharp red emission coming from Eu(III) 5 D 0 → 7 F J (J = 1–4) transitions can be enhanced by adjusting Eu concentrations and reaches the optimum at 20 at% Eu. Subsequently, the as-prepared NCs were transferred into an aqueous media via a ligand exchange by polyethyleneimine (PEI) to obtain the hydrophilic ZGO:Eu@PEI NCs. The initial fluorescent properties are preserved well. Finally, the strong red fluorescence emission, suitable excitation window, high photo-stability, excellent water solubility, and prominent bio-compatibility make ZGO:Eu@PEI NCs as high quality bio-imaging probes successfully identify living KB cells. The method mentioned in this paper overcomes the bottle-neck of the inorganic bulk phosphors as probes in bio-imaging, and as a result, expands their applications in optical detection and medical diagnosis fields. [ABSTRACT FROM AUTHOR]