Eu Nanoparticles Research Articles

Optically stimulated luminescence and radiophotoluminescence in NaMgF3:Eu nanoparticles

Optically stimulated luminescence and radiophotoluminescence were observed in NaMgF3:0.1%Eu nanoparticles synthesised via a hydrothermal technique. X-ray irradiation created F-centres, and subsequent optical stimulation at 420 nm released the electrons and electron-hole recombination produced Eu2+ emissions. The integrated optically stimulated luminescence intensity was linear up to 180 Gy. Photoluminescence was observed from Eu2+ and Eu3+ valences, whereas optically stimulated luminescence only occurred via the Eu2+ sites. X-ray irradiation also resulted in Eu3+ → Eu2+ and O2− → O− radiophotoluminescence effects, where the luminescence intensity ratio, RPLEu2+/RPLO2−, indicated a large detection range (>1 kGy). The observation of optically stimulated luminescence in lanthanide-doped near tissue-equivalent NaMgF3 nanoparticles has potential applications including as high spatial resolution two- and three-dimensional dosimeters for radiotherapy dose verification and validation. Radiophotoluminescence from oxygen-related centres and Eu is advantageous because it can provide a record of the dose history as well as an additional measure of the dose.

Plasma‐Generated Luminescent Coatings: Innovations in Thermal Sensitivity and Corrosion Resistance

AbstractThe strategic design of traditional coating materials has long been pivotal in broadening their range of applications. In this work, europium‐doped TiO2 coatings are grown in situ on the surface of titanium substrate using plasma electrolytic oxidation technology. The core reaction took no more than five minutes. Incorporating europium into the coating preserved the inherent corrosion resistance of PEO coatings while imparting anticipated thermal‐sensitive luminescence capabilities. The intrinsic emission of TiO2 and the characteristic emission of Eu3+ (5D0 → 7F2) are employed as the self‐reference for the LIR thermometry. The absolute and relative temperature sensitivity of the coating reached 0.0087 K−1 and 0.739% K−1, respectively. Notably, the coating exhibited a signal discriminability of up to 5100 cm−1 and a temperature uncertainty of only 0.18 K, which is comparable to some TiO2: Eu nanoparticles. The ingenious fusion of corrosion resistance and thermal‐sensitive luminescence of the coating not only makes it a classic protective structure but also facilitates its applicability to diverse scenarios, including optical thermometry in extreme environments.

Fluorescence of europium activated by molecular-like silver clusters for the detection of alkaline phosphatase activity

Alkaline phosphatase (ALP) is abnormally expressed in some cancers and promotes the growth, metastasis, and invasion of cancer cells. The detection of ALP is of great significance for both pathological study and clinical detection. In this work, a europium (Eu)-based fluorescence detection sensor was prepared in a mild reaction condition. LaF3:Eu nanoparticles was mixed with ethylene imine polymer (PEI) and Ag+ ions. PEI was used as stabilizer and reducing agent, and Ag+ ions were reduced as molecular-like silver clusters (ML-Ag NCs). The fluorescence of LaF3:Eu nanoparticles was enhanced by ML-Ag NCs through energy transfer. When ascorbic acid 2-phosphate (AAP) was hydrolyzed to ascorbic acid (AA) in the presence of ALP, AA reduced Ag+ ions to silver nanoparticles (Ag NPs) and quenched the fluorescence of LaF3:Eu/PEI/Ag. The activity of ALP was detected by measuring the fluorescence intensity of Eu3+ at 618 nm. In the concentration range from 2.0 to 16.0 U/L, the fluorescence intensity ratio ((F0–F)/F0) had a linear relationship with the logarithm of ALP concentration. The limit of detection (LOD) was 1.3 U/L. Moreover, the ALP activity was detected successfully in cancer cells by this method. The sensing platform has application potential in the detection of ALP activity in biological systems.

Layer formation, morphology and photoluminescent properties of ultrasonic spray of pre-formed YVO4:Eu and SiO2 coated ZnS:Mn nanoparticles

In this work, we study the coating process and coating quality of photoluminescent particles deposited on a glass surface in terms of particle distribution and associated film continuity. The dispersion process of commercial ZnS:Mn particles and YVO4:Eu particles synthesized by microwave reactor in aqueous solutions onto solid surface was performed using an ultrasonic atomizer. Two methods of particle deposition were used, one by moving the substrates while spraying and in the second the substrates were not moved. The measured zeta potential values of 42.9 mV and 45.3 mV, respectively, show that the dispersion of YVO4:Eu nanoparticles, in water, is stable at concentrations of 1.2 wt% and 2.4 wt% without the addition of capping agents. It was also found that the dispersion area increases as the flow rate increases from 1 ml/min to 3 ml/min at constant suspension concentration and spraying time. To stabilize the ZnS:Mn particles in solution, either surfactants or a silica capping layer prepared by a sol-gel process were used.The dispersion area encompassing the major amount of dispersed particles was evaluated, The SEM images demonstrate the effectiveness of the ultrasonic atomizer spraying procedure in the disaggregation nanoparticles, as seen by the reduced mean particle size in the sprayed layer compared to the as prepared powder. Finally, this study suggest that the dispersion process of photoluminescent nanoparticles on a substrate holds the potential for optical traceability.

Role of Zr3+ in excitation of Eu3+ ions in stabilized ZrO2:Eu nanoparticles

Microwave hydrothermal technique has been applied to crystallize ZrO2 nanoparticles with the sizes below 10 nm and activated with Eu. Trivalent europium ions acted also as the stabilization agent of the high temperature ZrO2 polymorphs at the room temperature. To achieve this, high concentrations - up to 20 % of Eu3+ - were introduced to the zirconia host lattice. Reference samples of ZrO2 containing yttrium were synthesized to obtain pure cubic, tetragonal and monoclinic phases at constant europium concentration. Eu3+ ions have not been reduced to divalent form, however, we have observed reduction of Zr4+ ions by means of luminescence spectroscopy and electron paramagnetic resonance (EPR). The variation of Zr3+ concentration in the samples with increasing Eu3+ content seems to support the concept of trivalent ion pairs as charge compensation centers in ZrO2. Excitation of Eu3+ ions was conducted via low and high symmetry sites. Trivalent zirconium ions have been found to play a role in the excitation of Eu3+ ions at low symmetry sites.

Synthesis and Properties of Eu and Ni Co-Doped ZnS Nanoparticles for the Detection of Ammonia Gas

Zinc sulfide nanoparticles were synthesized successfully via chemical co-precipitation, both in undoped form and co-doped with Europium (Eu) and Nickel (Ni). All prepared samples exhibited cubic zinc blende structure as confirmed by X-ray diffraction (XRD). The average particle size ranged from 3 to 6 nm for both pure and (Eu, Ni) co-doped ZnS, with no alteration in the crystal structure due to Eu and Ni co-doping. However, increasing the Ni dopant concentration (0, 2, 4, & 6 at%) while maintaining a constant Eu concentration (4 at%) led to an enhancement in the crystallite size. This was further validated by transmission electron microscopy (TEM), which showed particle sizes consistent with the XRD findings (3–5 nm). Microscopic analysis via scanning electron microscopy and TEM revealed spherical agglomerated morphology for the (Eu, Ni) co-doped nanoparticles. Energy-dispersive X-ray spectroscopy spectra confirmed the stoichiometric chemical composition of ZnS: Eu, Ni. Photoluminescence studies demonstrated an increased intensity of green luminescence at 6 at% Ni co-dopant concentration. Moreover, the synthesized samples exhibited promising gas sensing properties, particularly towards ammonia gas, with good selectivity. Notably, both pure and (Eu, Ni) co-doped ZnS nanoparticles showed rapid response and recovery times at room temperature, suggesting their potential applicability in gas sensing applications.

Rare-earth-based polymeric nanobubbles as tri-modal imaging contrast agent

Medical imaging plays an important role in providing sufficient guidance for disease diagnosis and treatment. Among them, multimodal contrast agents can combine with a variety of imaging technologies to obtain comprehensive information on the lesion. It is an important development direction of medical imaging for accurate diagnosis of most diseases. In this study, we have designed and prepared a novel nanocomposite (i.e. NaGdF4:Eu@PLGA NBs) by combining sulfur hexafluoride (SF6) loaded polylactic acid-co-glycolic acid (PLGA) nanobubbles (NBs) with NaGdF4:Eu nanoparticles (NPs), which is the first research work on the composite assembly of ultrasound contrast bubbles with rare earth nanomaterials. Results show that NaGdF4:Eu@PLGA NBs with a diameter of appropriately 220 nm had uniform size and good in vitro stability. Combined with PLGA NBs’ superior ultrasound (US) imaging characteristics and NaGdF4:Eu NPs’ excellent magnetic resonance imaging (MRI) and computed tomography (CT) imaging characteristics, NaGdF4:Eu@PLGA NBs have exhibited significant and long-term in vitro US imaging, MRI and CT tri-modal contrast enhancement capability. Taken together, NaGdF4:Eu@PLGA NBs have great potential to be utilized in biomedical applications of US/MRI/CT tri-modal imaging.

Structure and luminescence properties of EuF3 and SrF2:Eu nanoparticles after microwave plasma annealing in "methane-hydrogen".

Recently, progress has been made in fabricating diamond-based scintillators with integrated rare-earth luminescent particles. These luminescent particles are integrated into the bulk of diamond during their synthesis by chemical vapor deposition (CVD). However, the growth conditions include a chemically aggressive plasma environment and elevated temperatures, which results in the partial degradation of particles and a decrease in the intensity of their luminescence. Here, we investigate the effect of thermal annealing of luminescent EuF3 and SrF2:Eu powders in microwave plasma that simulates the growth conditions of polycrystalline diamond. It was found that silicon substrates act as efficient reducing agents that lead to the partial reduction of trivalent europium to divalent europium. When annealing occurs on a diamond substrate, the reduction processes proceed at a significantly slower rate. The observed luminescence spectra showed both Eu2+ and Eu3+ luminescence bands, which allows for a targeted tuning of the luminescence spectrum of europium in composites and can be used to fabricate detectors and visualizers of X-ray radiation using a visible signal from the desired combination of Eu2±/Eu3± ions. During plasma annealing in pure hydrogen at moderate temperatures (600 °C), an intensive hydrogenation of particles is observed. Such hydrogen plasma treatment of fluorides may be considered a promising route to fabricate hydrides of various metals.

EuIII and TbIII upconversion intermediated by interparticle energy transfer in functionalized NaLnF4 nanoparticles.

Lanthanide (LnIII)-doped sodium gadolinium tetrafluoride (NaGdF4) nanoparticles have been excelled as attractive upconversion systems for anti-counterfeiting or energy conversion for instance, with a special interest in the visible upconversion of EuIII and TbIII. The core@shell architecture has enabled the bright upconversion of EuIII and TbIII in this matrix by interfacial energy transfer sensibilized by the TmIII/YbIII pair. Another approach to enable EuIII and TbIII upconversion could be the interparticle energy transfer (IPET) between LnIII-doped sensitizer and acceptor nanoparticles. Yet, the low molar absorptivity of the LnIII through 4f ↔ 4f electronic transitions and the large distance between the nanoparticles are shortcomings that should decrease the energy transfer efficiency. On the other hand, it is feasible to predict that the association of organic ligands displaying large molar absorptivity on the acceptor nanoparticle surface could help to overcome the absorption limitation. Inspired by this exciting possibility, herein, we present the EuIII/TbIII upconversion intermediated by IPET between the donor TmIII, YbIII-doped NaGdF4 nanoparticle and the acceptor LnIII-doped NaGdF4 (Ln = Eu and/or Tb) nanoparticles functionalized with a series organic ligands on the surface (tta- = thenoyltrifluoroacetonate, acac- = acetylacetonate, or 3,5-bbza- = 3,5-dibromebenzoate). Either in solid state or in suspension, upon excitation at 980 nm, visible EuIII/TbIII upconversion could be observed. This emission comes from the absorption of the TmIII, YbIII pair in the donor nanoparticle, followed by IPET from the TmIII excited levels to the ligand singlet/triplet states on the acceptor nanoparticle surface, ligand-to-EuIII/TbIII energy transfer, and upconversion emission. Spectroscopic evidences from the analysis of the donor level lifetimes indicate the contribution of non-radiative energy transfer for the IPET mechanism; the radiative mechanism also contributes for the IPET. Moreover, the design herein introduced enables the development of luminescence temperature probes with relative thermal sensitivity as high as 1.67% K-1 at 373 K. Therefore, this new upconversion pathway opens an avenue of possibilities in an uncharted territory to tune the visible upconversion of LnIII ions.

LnPO4:Eu3+ nanoparticles: Role of host lattices on physiochemical and luminescent properties

LnPO4:Eu3+ (Ln = La, Gd and Y) nanoparticles (NPs) were prepared at low temperatures via a urea-based thermal decomposition method. X-ray diffraction pattern revealed a hexagonal single phase, high purity with an average crystalline size of 13.9, 14.89, and 18.7 nm for LaPO4:Eu, GdPO4:Eu, and YPO4:Eu NPs, respectively. Bandgap energies were calculated based on the measure absorption spectra are to be values 5.14, 5.03, and 4.90 eV for the LaPO4:Eu, GdPO4:Eu, and YPO4:Eu NPs, respectively. A comparative study suggested that the excitation and emission transitions were significantly higher in the GdPO4:Eu NPs and in comparison to the LaPO4:Eu and YPO4:Eu NPs. It implies the impact of the crystallinity, host lattice, and crystal symmetry, in which doped Eu3+-ion replaces the host cation and distorts the crystal symmetry.

Massive sensitisation of Eu3+ photoluminescence in NaMgF3:Eu nanoparticles by 2-thenoyltrifluoroacetone ligand exchange

NaMgF3:0.1%Eu nanocuboids capped with oleic acid were synthesised via a hydrothermal synthesis technique. Subsequent ligand exchange using 2-thenoyltrifluoroacetone resulted in a massive sensitisation of the Eu3+ photoluminescence where the intensity of the 5D0 → 7F2 transition increased by over 40 000×, relative to the oleic acid-capped nanoparticles. Large Judd-Ofelt Ω2 parameters indicated that the sensitised Eu3+ emissions originated primarily from distorted Eu3+ sites near the nanoparticle surfaces. The massive enhancement of the Eu3+ photoluminescence in 2-thenoyltrifluoroacetone sensitised NaMgF3:Eu nanoparticles encourages applications that include ultra-high resolution optical temperature sensors and dosimeters.

Investigation of the Biodistribution of Gd0.5La0.5F3:Eu Nanoparticles in the Internal Tissues of Laboratory Mice Using X-Ray Computed Tomography and X-Ray Fluorescence Analysis

Investigation of the Biodistribution of Gd0.5La0.5F3:Eu Nanoparticles in the Internal Tissues of Laboratory Mice Using X-Ray Computed Tomography and X-Ray Fluorescence Analysis

Ligand Induced Morphology Change and Enhancement of Luminescence Emission in CaF2:Eu(III) Nanoparticles: The Role of Ethylene Glycol, Trisodium Citrate and EDTA in Tuning the Particle Size in Seeded-Growth Approach

Ligand Induced Morphology Change and Enhancement of Luminescence Emission in CaF2:Eu(III) Nanoparticles: The Role of Ethylene Glycol, Trisodium Citrate and EDTA in Tuning the Particle Size in Seeded-Growth Approach

Europium oxide modified reduced graphene oxide composite for trace detection of hydrogen phosphate ions in soil samples

The phosphate (PO43−) ion is a constituent of the environment, soil, plants, and animals. There should be a real-time and portable phosphate detection sensor. Herein we propose a colorimetry based sensitive method for hydrogen phosphate (HPO42−) ions detection using europium oxide modified reduced graphene oxide composite (Eu2O3-RGO) and gold nanoparticles (Au NPs). We detect the HPO42− by observing the anti-aggregation of gold nanoparticles. In the presence of a Eu2O3-RGO composite, the Au NPs underwent an aggregation process, causing a colour change of Au NPs from wine red to wine blue. Once Eu-modified RGO was pre-mixed with HPO42− ions and introduced into Au NPs, the Eu nanoparticles in the Eu-modified RGO were attracted to the HPO42− ions. Because of this, the aggregated Au NPs started to anti-aggregate, and the colour of Au NPs changed from wine blue to wine red. The calibration curve of the sensor goes from 0 nM to 500 nM concentration of HPO42− ions. Our sensor has a detection limit of 0.08 nM, which is lower than the reported values. This improved lower detection limit is probably due to the use of RGO, which according to the literature review, can adsorb phosphate ions onto its surface. We optimized the incubation time and europium oxide (Eu2O3) nanoparticle concentration to improve the sensor's sensitivity. Lastly, we tested an agricultural sample using our developed method.

Ln2O3:Eu nanoparticles: host lattices and their impact on photoluminescence, Raman, optical, and crystal properties

Ln2O3:Eu nanoparticles: host lattices and their impact on photoluminescence, Raman, optical, and crystal properties

Optical properties, singlet oxygen, and free radical production ability with different UV irradiations and antimicrobial inhibitors against various bacterial species of ZnO: Eu nanoparticles

In this study, ZnO: Eu nanoparticles were produced by the co-precipitation method. In this context, X-ray diffraction (XRD) was analyzed to characterized the produced nanoparticles. Moreover, the approximate crystallite size of the nanoparticles was calculated using Scherrer's formula and Williamson-Hall's equation of 27 nm with a strain of 0.002. The crystalline size and the microstructure of ZnO: Eu nanoparticles were obtained by the scanning electron microscope (SEM) and its results were consistent with the analysis of (XRD). The optical properties of the prepared nanostructure were studied by applying photoluminescence spectroscopy (PL), which was observed in the spectrum obtained with an excitation wavelength of 325 nm in the ultraviolet range and visible zone of the peaks. The energy band gap was reached through ultraviolet-visible spectroscopy for ZnO: Eu nanoparticles. The connection between the produced nanostructure elements was defined by the Fourier transform infrared spectroscopy (FTIR). Methylene blue and anthracene reagents were used to detect the hydroxyl radical and singlet oxygen. The reduction in anthracene and methylene blue absorption emphasizes the production of singlet oxygen and radical hydroxyl. ZnO: Eu nanoparticles were used as an antimicrobial inhibitor against various bacterial species. Taken together, our results confirmed that the growth of bacteria can be inhibited by ZnO: Eu nanoparticles. The maximum diameter of the halo was not increased, due to the effect of 26 mm nanoparticles that is related to P.aeruginosa bacteria.

Europium doped titanium dioxide nanocrystalline: synthesis, structure and optical properties

Abstract
 Uniform, spherical-shaped TiO2: Eu nanoparticles with different doping concentrations were synthesized using the sol-gel method. The structural, morphology, optical, luminescent, and surface properties of the samples were investigated at different Eu3+ concentration. The morphology, crystalline structure, and chemical composition of the samples were characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The X-ray diffraction results reveal that the obtained powder nanoparticles consist of a single phase tetragonal structure. The crystallite sizes calculated by utilizing Scherrer’s equation were found in the range of 18.94 – 7.77 nm for TiO2:Eu samples annealed at 550οC. The SEM images reveal an irregular agglomerated morphology indicating a decrease in particle size with an increase in Eu3+ concentration. X-ray photoelectron spectroscopy (XPS) high resolution spectra of the Ti-2p peak confirmed that Ti atoms were in a doubly ionized state, and the deconvolution of the O1s XPS peak show the presence of oxygen related defects in the sample. EDS results confirm a systematic increase of Eu content in the as-prepared samples with the increase of europium concentration. Incorporation of europium in the titania particles induces a structural deformation and a blueshift of their absorption edge. The luminescence intensity increases with Eu3+ concentration up to 3 mol% and then quenched. While the PL emission of the as-grown samples is dominated by the 5D0 - 7Fj transition of Eu3+ ions, the emission intensity reduces drastically after thermal annealing due to outwards segregation of dopant ions.
 Keywords: Titanium dioxide; Photoluminescence Spectroscopy; XPS; Nanocrystalline; Anatase; Rutile. 

Eu3+-ion doped LnF3 NPs: Comparative study of the crystallographic, and photophysical properties

The thermal co-precipitation approach was employed for the synthesis of the Eu3+-ion doped YF3, LaF3, and GdF3 nanoparticles (NPs) and compared their photophysical properties. Ammonium fluorite was used as a fluorine source for the synthesis of metal fluorides at lower temperatures. Luminescent lanthanide fluoride (LnF3) NPs were characterized by different techniques containing X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), FT-Raman, UV/Visible absorption spectra, and photoluminescence spectroscopic procedures to investigate the crystal structural, thermal, Raman effect, surface, optical, and luminescent properties. XRD study shows two types of crystal phase orthorhombic in YF3:Eu & GdF3:Eu and hexagonal in LaF3:Eu NPs. TGA, FTIR, and absorption spectra studies show the exterior adsorbed –OH molecules, which assist in the development of colloidal solution in aqueous media. Raman vibrations were strongly affected which were correlated with the XRD reflection planes. In comparative photo-physical properties, the excitation and emission spectra exhibited remarkable intensities of the Eu3+-ion transitions. Similarly, the emission spectra of all three samples exhibited the highest emission efficiency of the magnetically-dipole(5D0→7F2) transition in comparison to the electric-dipole 5D0→7F1 transition, which reflected the transformation of the crystal symmetry. Comparative analysis was presented to investigate the role of the host lattice on crystallinity, thermal stability, and luminescent properties. These findings are highly fruitful in designing photonic-based applications including optical biosensors, fingermark detection, security systems, etc.

Dopant-induced red emission, paramagnetism, and hydrogen evolution of diluted magnetic semiconductor ZnS: Eu nanoparticles

Dopant-induced red emission, paramagnetism, and hydrogen evolution of diluted magnetic semiconductor ZnS: Eu nanoparticles

Facile synthesis of ZnO/CuO/Eu heterostructure photocatalyst for the degradation of industrial effluent

Zinc oxide-based ternary heterostructure ZnO/CuO/Eu(1%, 3%, and 5% of Eu) nanoparticles were effectively produced by employing Vigna unguiculata(cowpea)waste skin extract as fuel in a simple one-pot combustion process. The as-synthesized heterostructure was analyzed by X-ray diffraction studies, ultraviolet-visible spectroscopy, Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscopy, and High-Resolution Transmission Electron Microscopy techniques. Besides, the photocatalytic degradation efficiency of the as-obtained ternary nanocomposite was evaluated under UV light for the degradation of model organic pollutants including methylene blue (MB), Rhodamine-B (RB), and an effluent sample collected from the textile industrial waste. During this study, the effect of a variety of parameters on the photodegradation activity of the photocatalysts has been thoroughly evaluated, such as light source, catalyst dose, irradiation period, dye concentration, solution pH, etc. Under UV irradiation(100 mins), the ternary ZnO/CuO/Eu photocatalyst demonstrated excellent degradation activity of ∼99 and ∼93% for MB and RB, respectively, while for the industrial effluent, a decent degradation activity of 42% has been recorded. Further experiments have revealed a pH and concentration-dependent photocatalytic behavior of the heterostructure photocatalyst. Therefore, the results suggest that the heterostructure photocatalyst can be potentially applied for wastewater treatment and other environmental applications.