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The study reveals the comparison of Nd0.9Pr0.1CrO3 and Nd0.9Eu0.1CrO3 samples where the A-site is doped by Pr3+ having the larger ionic radius (1.126 A°) corresponding to less chemical pressure and Eu3+ (1.066 A°) having the smaller ionic radius corresponding to enhanced chemical pressure exerted on the NdCrO3, with the help of X-ray diffraction, Raman spetroscopy, UV-visible spectroscopy, and dc magnetization measurements. The different spin configuration Pr3+ (J = 4) and Eu3+ (J = 0) altering the strong coupling between Nd3+ (J = 9/2) and Cr3+ (S = 3/2) spins result in the variation of the optical band gap, fermi energy and exchange bias.

The fluorescent vesicles based on lanthanide ions are considered as an ideal biomimetic optical nanoplatform for simulating biological processes of cell membrane. However, the accurately and controllably adjusting the size of vesicles based on lanthanides while ensuring their fluorescence performance and stability still remains a challenge. Herein, a dual-stimuli-responsive fluorescent supramolecular vesicle with tunable size has been designed based on host-guest interaction and coordinating aggregation. Europium complexes can be encapsulated within supramolecular assemblies by assembling with polypseudorotaxanes (PPRs), which are formed by F127 and carboxymethyl-β-cyclodextrin (CMCD) through host-guest interaction. The fluorescence properties of the europium complexes have been significantly enhanced by confining and shielding them within vesicles. Upon the addition of α-amylase and HCl, the fluorescence intensity of the vesicles will gradually and significantly quench as a result of CMCD degradation and dissociation of the europium complexes. This research presents a convenient method for regulating the size of lanthanide fluorescent vesicles, and the supramolecular vesicles obtained with multi-stimuli response are anticipated to be utilized in the diagnosis of relevant diseases and targeted drug delivery.

Cerium oxide nanoparticles (CeONPs) exhibiting antioxidant properties are investigated as potential tools for neurodegenerative diseases. Here, we synthesized polyacrylic acid conjugated cerium oxide (CeO) nanoparticles, and further to enhance their neuroprotective effect, Eu[sup.3+] was substituted at different concentrations (5, 10, 15 and 20 mol%) to the CeO, which can also impart fluorescence to the system. CeONPs and Eu-CeONPs in the size range of 15–30 nm were stable at room temperature. The X-ray Photoelectron Spectroscopy (XPS) analysis revealed the chemical state of Eu and Ce components, and we could conclude that all Eu[sup.3+] detected on the surface is well integrated into the cerium oxide lattice. The emission spectrum of Eu-CeO arising from the [sup.7]F[sub.0] → [sup.5]D[sub.1] MD and [sup.7]F[sub.0] → [sup.5]D[sub.2] transitions indicated the Eu[sup.3+] ion acting as a luminescence center. The fluorescence of Eu-CeONPs was visualized by depositing them at the surface of positively charged latex particles. The developed nanoparticles were safe for human neuronal-like cells. Compared with CeONPs, Eu-CeONPs at all concentrations exhibited enhanced neuroprotection against 6-OHDA, while the protection trend of Eu-CeO was similar to that of CeO against H[sub.2]O[sub.2] in SH-SY5Y cells. Hence, the developed Eu-CeONPs could be further investigated as a potential theranostic probe.

The luminous efficiency of white light-emitting diodes, which are used as light sources for next-generation illumination, is continuously improving. Presently available white light-emitting diodes emit with extremely high luminance because their emission areas are much smaller than those of conventional light sources. Consequently, white light-emitting diodes produce a glare that is uncomfortable to the human eye. Here we report a yellow-emitting phosphor, the Eu 2+ -doped chlorometasilicate (Ca 1-x-y , Sr x , Eu y ) 7 (SiO 3 ) 6 Cl 2 , which can be used to create glareless white light-emitting diodes. The (Ca 1-x-y , Sr x , Eu y ) 7 (SiO 3 ) 6 Cl 2 exhibits a large Stokes shift, efficiently converting violet excitation light to yellow luminescence, and phosphors based on this host material have much less blue absorption than other phosphors. We used crystal structure analysis to determine the origin of the desired luminescence, and we used (Ca 1-x-y , Sr x , Eu y ) 7 (SiO 3 ) 6 Cl 2 and a blue-emitting phosphor in combination with a violet chip to fabricate glareless white light-emitting diodes that have large emission areas and are suitable for general illumination. Light-emitting diodes are attractive sources of light used in an increasing range of applications. This study presents a novel europium-based phosphor that gives rise to a substantial reduction in the glare that often makes LEDs uncomfortable to the human eye.

Activated trivalent lanthanide (Eu 3+ ) inorganic nanoparticles were regarded as the best possible alternative to conventional molecular bio probes and highly appropriate for use as sensitive time-resolved PL bio probes for bio-detection. Because of their strong photochemical stability, unique crisp emission lines, and high quantum efficiencies, rare-earth-based nanomaterials are the most utilized luminous materials. Furthermore, the coupling of vibrational modes of other molecules over the surface of the rare earth nanoparticles and other surface imperfections causes emission quenching. One potential strategy for preventing or minimizing these effects is to use a passivation agent that interacts with the surface of the nanoparticles. This study focuses on the passivation of tri-octyl phosphine oxide (TOPO) with europium oxide to form in-situ hydrophobic TOPO shell europium oxide nanoparticles for improving the physical, chemical, and optical properties of Eu 3+ ions. The Eu:TOPO ratio of the nanoparticle was optimized for effective photoluminescence and particle crystallinity by photoluminescence spectroscopy and XRD analysis. The controlled size and shape of the material were analyzed by FESEM and EDS studies. Further, the XPS, Raman spectroscopy, and 1 H-NMR studies examined the incorporation of TOPO with europium oxide nanoparticles. The optical properties of the TOPO-capped europium oxide nanoparticles were evaluated by UV-Vis DRS and time-resolved fluorescence spectroscopy. Thus, this study is based on the efficiency of varied TOPO capping ratios with synthesized europium oxide nanoparticles in generating a size-regulated, highly stable, and effective luminous material with a higher quantum yield than europium oxide.

The biorecovery of europium (Eu) from primary (mineral deposits) and secondary (mining wastes) resources is of interest due to its remarkable luminescence properties, important for modern technological applications. In this study, we explored the tolerance levels, reduction and intracellular bioaccumulation of Eu by a site-specific bacterium, Clostridium sp. 2611 isolated from Phalaborwa carbonatite complex. Clostridium sp. 2611 was able to grow in minimal medium containing 0.5 mM Eu 3+ . SEM-EDX analysis confirmed an association between Eu precipitates and the bacterium, while TEM-EDX analysis indicated intracellular accumulation of Eu. According to the HR-XPS analysis, the bacterium was able to reduce Eu 3+ to Eu 2+ under growth and non-growth conditions. Preliminary protein characterization seems to indicate that a cytoplasmic pyruvate oxidoreductase is responsible for Eu bioreduction. These findings suggest the bioreduction of Eu 3+ by Clostridium sp. as a resistance mechanism, can be exploited for the biorecovery of this metal.

This paper reports the synthesis, structure, photophysical, and optoelectronic properties of five eight-coordinate Europium(III) ternary complexes, namely, [Eu(hth)3(L)2], bearing 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione (hth) as a sensitizer and L = H2O (1), dpso (diphenyl sulphoxide, 2), dpsoCH3 (4,4′-dimethyl diphenyl sulfoxide, 3), dpsoCl (bis(4-chlorophenyl)sulphoxide, 4), and tppo (triphenylphosphine oxide, 5) as co-ligands. The NMR and the crystal structure analysis confirmed the eight-coordinate structures of the complexes in solution and in a solid state. Upon UV-excitation on the absorption band of the β-diketonate ligand hth, all complexes showed the characteristic bright red luminescence of the Europium ion. The tppo derivative (5) displayed the highest quantum yield (up to 66%). As a result, an organic light-emitting device, OLED, was fabricated with a multi-layered structure—ITO/MoO3/mCP/SF3PO:[complex 5] (10%)/TPBi:[complex 5] (10%)/TmPyPB/LiF/Al—using complex 5 as the emitting component.

Acrylic resin is a polymer with strong crosslinking density and strength, and it is commonly used as a matrix in water-based coatings. Barium europium phosphate (Ba3Eu(PO4)3) is a novel functional filler that is expected to provide anti-corrosive effects to coatings. In this study, Ba3Eu(PO4)3 was prepared by the high-temperature solid-phase method and applied to acrylic anti-corrosion coatings. The influence of the molar ratio of reactants on Ba3Eu(PO4)3 purity was studied. The anti-corrosion performance of the coating was investigated. It was found that, when BaCO3:Eu2O3:(NH4)H2PO4 = 3:0.5:3 and the reaction was carried out at 950 °C for 1000 min, high-purity Ba3Eu(PO4)3 can be obtained, according to XRD and EDS tests. SEM shows that Ba3Eu(PO4)3 has good crystal morphology and a porous morphology. TEM revealed that its structure was intact. When Ba3Eu(PO4)3 was added to a relative resin content of 5 wt%, the anti-corrosion performance of the coating was the best after 168 h, with the lowest Tafel current density of 9.616 μA/cm2 and the largest capacitance arc curvature radius. The salt spray resistance test showed that the corrosion resistance of the 5 wt% Ba3Eu(PO4)3 coating was also the best, which is consistent with the results of the electrochemical test. Ba3Eu(PO4)3 as a pigment and filler can effectively improve the anti-corrosion performance of water-based industrial coatings.

The layered orthorhombic quaternary tellurides EuRECuTe3 (RE = Ho, Tm, Sc) with Cmcm symmetry were first synthesized. Single crystals of the compounds up to 500 μm in size were obtained by the halide-flux method at 1120 K from elements taken in a ratio of Eu/RE/Cu/Te = 1:1:1:3. In the series of compounds, the changes in lattice parameters were in the ranges a = 4.3129(3)–4.2341(3) Å, b = 14.3150(9)–14.1562(9) Å, c = 11.2312(7)–10.8698(7) Å, V = 693.40(8)–651.52(7) Å3. In the structures, the cations Eu2+, RE3+ (RE = Ho, Tm, Sc), and Cu+ occupied independent crystallographic positions. The structures were built with distorted copper tetrahedra forming infinite chains [CuTe4]7− and octahedra [RETe6]9− forming two-dimensional layers along the a-axis. These coordination polyhedra formed parallel two-dimensional layers CuRETe32−∞2. Between the layers, along the a-axis, chains of europium trigonal prisms [EuTe6]10− were located. Regularities in the variation of structural parameters and the degree of distortion of coordination polyhedra depending on the ionic radius of the rare-earth metal in the compounds EuRECuCh3 (RE = Ho, Er, Tm, Lu, Sc; Ch = S, Se, Te) were established. It is shown that with a decrease in the ionic radius ri(RE3+) in the compounds EuRECuTe3, the unit-cell volume, bond length d(RE–Te), distortion degree [CuTe4]7−, and crystallographic compression of layers [RECuTe3]2− decreased. The distortion degree of tetrahedral polyhedra [CuCh4]7−, as well as the structural parameters in europium rare-earth copper tellurides EuRECuTe3, were higher than in isostructural quaternary chalcogenides. Ab initio calculations of the crystalline structure, phonon spectrum, and elastic properties of compounds EuRECuTe3 (RE = Ho, Tm, and Sc) ere conducted. The types and wave numbers of fundamental modes were determined, and the involvement of ions in IR and Raman modes was assessed. The calculated data of the crystal structure correlated well with the experimental results.

The components with soft nature in the metal halide perovskite absorber usually generate lead (Pb)⁰ and iodine (I)⁰ defects during device fabrication and operation. These defects serve as not only recombination centers to deteriorate device efficiency but also degradation initiators to hamper device lifetimes. We show that the europium ion pair Eu3+-Eu2+ acts as the “redox shuttle” that selectively oxidized Pb⁰ and reduced I⁰ defects simultaneously in a cyclical transition. The resultant device achieves a power conversion efficiency (PCE) of 21.52% (certified 20.52%) with substantially improved long-term durability. The devices retained 92% and 89% of the peak PCE under 1-sun continuous illumination or heating at 85°C for 1500 hours and 91% of the original stable PCE after maximum power point tracking for 500 hours, respectively.