Interpretation of europium(III) spectra

Crystal structures and intense luminescence of tris(3-(2′-pyridyl)-pyrazolyl)borate Tb3+ and Eu3+ complexes with carboxylate co-ligands

The carboxylate coligands affect the bright luminescence of a series of Eu³⁺ and Tb³⁺ complexes.

Unusual extraction of trivalent f-cations using diglycolamide dendrimers in a room temperature ionic liquid: extraction, spectroscopic and DFT studies

The complexation of Am³⁺ and Eu³⁺ was studied with three generations of DGA-Den ligands in a room temperature ionic liquid.

Hydrophilic 2,9-bis-triazolyl-1,10-phenanthroline ligands enable selective Am(iii) separation: a step further towards sustainable nuclear energy

An exciting new family of hydrophilic ligands for the selective extraction of Am(iii) from spent nuclear fuel are reported herein.

Optical thermometry based on thermal population of low-lying levels of Eu3+ in Ca2.94Eu0.04Sc2Si3O12

Non-contact optical thermometry using rare-earth materials has attracted a lot of attention due to its realization of non-invasive and real-time temperature determination.

Effect of CdS nanocrystals on the photoluminescence of Eu3+-doped silicophosphate sol gel glass

In this work, we investigate the effect of co-doping with CdS nanoparticles on the photoluminescence properties of Eu³⁺ doped silicophosphate glass prepared via the sol gel method.

Benzene-centred tripodal diglycolamides for the sequestration of trivalent actinides: metal ion extraction and luminescence spectroscopic investigations in a room temperature ionic liquid

Three benzene-centred tripodal diglycolamide (Bz-T-DGA) ligands were evaluated for actinide ion extraction/complexation in an ionic liquid medium.

Tuning the structure and Zn(ii) sensing of lanthanide complexes with two phenylimidazophenanthrolines by acetonitrile hydrolysis

1D/0D lanthanide complexes of phenylimidazophenanthrolines were constructedviahydrolysis of acetonitrile, and0-Eushows prompt photoemission response to Zn²⁺.

Dimer formation of GdDO3A-arylsulfonamide complexes causes loss of pH-dependency of relaxivity

Coordination of peripheral carboxylates intended for bioconjugation dramatically changes the Gd(iii) coordination properties of DO3A-sulfonamide ligands.

Luminescence-colour-changing sensing of Mn2+ and Ag+ ions based on a white-light-emitting lanthanide coordination polymer

A white-light-emitting LnCP is effectively applied to the detection of Ag⁺ and Mn²⁺ ions with high selectivity and sensitivity via luminescence-colour change.

A thermochromic europium(iii) room temperature ionic liquid with thermally activated anion–cation interactions

An observable and reversible case of thermochromism due to an unusual interaction between the countercation and the ligand of an europium(iii) tetrakis-β-diketonate room temperature ionic liquid is reported.

Structural, optical and phonon properties of formate-based MOF phosphors with ethylammonium cations

We report the structural and spectroscopic properties of metal–organic phosphors.

Synthesis and electronic investigation of mono- and di-substituted 4-nitro- and 4-amino-pyrazol-1-yl bis(pyrazol-1-yl)pyridine-type ligands and luminescent Eu(iii) derivatives

The synthesis of nitro- and amino-bis(pyrazol-1-yl)pyridines was achieved, allowing for tuning of frontier orbital energies and Eu(iii) complex spectroscopic investigations.

Synthesis, structure, and photoluminescent behaviour of molecular lanthanide–2-thiophenecarboxylate–2,2′:6′,2′′-terpyridine materials

A lanthanide series incorporating 2-thiophenecarboxylate and terpyridine is presented. Four structure types are observed with differences in the coordination number and nuclearity of the complexes attributed to the effects of the lanthanide contraction.

In situ luminescence analysis: a new light on monitoring calcium phosphate phase transitions

In situ luminescence measurements allow monitoring the phase transitions of biologically relevant calcium phosphates with high sensitivity, independent of synchrotron radiation.

Solvent-dependent dual-luminescence properties of a europium complex with helical π-conjugated ligands

A europium(iii) complex with a large π-conjugated helical ligand, tris(hexafluoroacetylacetonato)europium(iii)bis((pentahelicenyl)diphenylphosphine oxide) (Eu(hfa)₃(HPO)₂), exhibits dual luminescence excited at the π–π* transition band.

Facile access to efficiently luminescent Ln3+ phosphonic ester coordination polymers (Ln = Eu, Tb, Dy)

Efficiently luminescent coordination polymers containing lanthanide ions (Eu³⁺, Tb³⁺, Dy³⁺) can be easily obtained using a suitable bisphosphonic ester from which a heterometallic version can be elaborated showing white light emission.

Site-selective Eu(iii) spectroscopy of highly efficient luminescent mixed-metal Pb(ii)/Eu(iii) coordination polymers

Novel coordination polymers based on Pb_1−xEu_x–BDC (x = 0.05–0.50, BDC = 1,4-benzenedicarboxylic acid) are reported with a maximum emission quantum yield of 69 ± 7%.

Effects of electron-withdrawing groups in imidazole-phenanthroline ligands and their influence on the photophysical properties of EuIII complexes for white light-emitting diodes

The red light emitting diode (LED) was fabricated by using europium complexes with InGaN LED (395 nm) and shown digital images, corresponding CIE color coordinates (red region) as well as obtained highest quantum yield of the thin film (78.7%).

Hard-and-soft phosphinoxide receptors for f-element binding: structure and photophysical properties of europium(iii) complexes

New phosphinoyl-based tetradentate heterocycles and their phosphorescent Eu(iii) complexes prepared and characterized.

Monitoring the mechanism of formation of [Ce(1,10-phenanthroline)2(NO3)3] by in situ luminescence analysis of 5d–4f electronic transitions

The mechanism of formation of emitting complexes is efficiently elucidated by in situ luminescence measurements of 5d–4f electronic transitions from the early stages of the reaction until the final product crystallization.

Site-selective Eu3+ luminescence in Sr2ScLi(B2O5)2

Unit cell of Sr₂ScLi(B₂O₅)₂ borate.

Origin of Blue-Green Emission in α-Zn2P2O7 and Local Structure of Ln3+ Ion in α-Zn2P2O7:Ln3+ (Ln = Sm, Eu): Time-Resolved Photoluminescence, EXAFS, and DFT Measurements

Considering the fact that pyrophosphate-based hosts are in high demand for making highly efficient luminescence materials, we doped two visible lanthanide ions, viz. Sm³⁺ and Eu³⁺, in Zn₂P₂O₇. Interestingly, it was oberved that pure Zn₂P₂O₇ displayed blue-green dual emission on irradiation with ultraviolet light. Emission and lifetime spectroscopy shows the presence of defects in pyrophosphate samples which are responsible for such emission. DFT calculations clearly pinpointed that the electronic transitions between defect states located at just below the conduction band minimum (arises due to V_O¹⁺ and V_O²⁺ defects) and valence band maximum, as well as impurity states situated in the band gap, can lead to dual emission in the blue-green region, as is also indicated by emission and lifetime spectra. X-ray absorption near edge spectroscopy (XANES) shows the stabilization of europium as well as samarium ion in the +3 oxidation state in α-Zn₂P₂O₇. The fact that α-Zn₂P₂O₇ has two different coordination numbers for zinc ions, i.e. five- and six-coordinate, the study of dopant ion distribution in this particular matrix will be an important step in realizing a highly efficient europium- and samarium-based red-emitting phosphor. Time resolved photoluminescence (TRPL) shows that both of these ions are heterogeneously distributed between five- and six-coordinated Zn²⁺ sites and it is the six-coordinated Zn²⁺ site which is the most favorable for lanthanide ion doping. Extended X-ray absorption fine structure (EXAFS) measurements also suggested that a six-coordinated zinc ion is the preferred site occupied by trivalent lanthanide ions, which is in complete agreement with TRPL results. It was observed that there is almost complete transfer of photon energy from Zn₂P₂O₇ to Eu³⁺, whereas this transfer is inefficient and almost incomplete in case of Sm³⁺, which is indeed important information for the realization of pyrophosphate-based tunable phosphors.

Conversion of Biowaste Asian Hard Clam (Meretrix lusoria) Shells into White-Emitting Phosphors for Use in Neutral White LEDs

The increasing volume and complexity of waste associated with the modern economy poses a serious risk to ecosystems and human health. However, the remanufacturing and recycling of waste into usable products can lead to substantial resource savings. In the present study, clam shell waste was first transformed into pure and well-crystallized single-phase white light-emitting phosphor Ca₉Gd(PO₄)₇:Eu²⁺,Mn²⁺ materials. The phosphor Ca₉Gd(PO₄)₇:Eu²⁺,Mn²⁺ materials were synthesized by the solid-state reaction method and the carbothermic reduction process, and then characterized and analyzed by means of X-ray diffraction (XRD) and photoluminescence (PL) measurements. The structural and luminescent properties of the phosphors were investigated as well. The PL and quantum efficiency measurements showed that the luminescence properties of clam shell-based phosphors were comparable to that of the chemically derived phosphors. Moreover, white light-emitting diodes were fabricated through the integration of 380 nm chips and single-phase white light-emitting phosphors (Ca_0.979Eu_0.006Mn_0.015)₉Gd(PO₄)₇ into a single package of a white light emitting diode (WLED) emitting a neutral white light of 5298 K with color coordinates of (0.337, 0.344).

Luminescence and Luminescence Quenching of K2Bi(PO4)(MoO4):Eu3+ Phosphors with Efficiencies Close to Unity

A very good light emitting diode (LED) phosphor must have strong absorption, high quantum efficiency, high color purity, and high quenching temperature. Our synthesized K₂Bi(PO₄)(MoO₄):Eu³⁺ phosphors possess all of the mentioned properties. The excitation of these phosphors with the near-UV or blue radiation results in a bright red luminescence dominated by the ⁵D₀ → ⁷F₂ transition at ∼615 nm. Color coordinates are very stable when changing Eu³⁺ concentration or temperature in the range of 77-500 K. Furthermore, samples doped with 50% and 75% Eu³⁺ showed quantum efficiencies close to 100% which is a huge benefit for practical application. Temperature dependent luminescence measurements showed that phosphor performance increases with increasing Eu³⁺ concentration. K₂Eu(PO₄)(MoO₄) sample at 400 K lost only 20% of the initial intensity at 77 K and would lose half of the intensity only at 578 K. Besides, the ceramic disks with thicknesses of 0.33 and 0.89 mm were prepared from K₂Eu(PO₄)(MoO₄) powder, and it turned out that they efficiently converted the radiation of 375 nm LED to the red light. The conversion of 400 nm LED radiation to the red light was not complete; thus, the light sources with various tints of purple color were obtained. The combination of ceramic disks with 455 nm LED yielded the light sources with tints of blue color due to the low absorption of ceramic disk in this spectral range. In addition, these phosphors possess a very unique emission spectra; thus, they could also be applied in luminescent security pigments.

Study of the Interaction of Eu3+ with Microbiologically Induced Calcium Carbonate Precipitates using TRLFS

The microbial induced biomineralization of calcium carbonate using the ureolytic bacterium Sporosarcina pasteurii in the presence of trivalent europium, a substitute for trivalent actinides, was investigated by time-resolved laser-induced fluorescence spectroscopy (TRLFS) and a variety of physicochemical techniques. Results showed that the bacterial-driven hydrolysis of urea provides favorable conditions for CaCO₃ precipitation and Eu³⁺ uptake due to subsequent increases in NH₄⁺ and pH in the local environment. Precipitate morphologies were characteristic of biogenically formed CaCO₃ and consistent with the respective mineral phase compositions. The formation of vaterite with some calcite was observed after 1 day, calcite with some vaterite after 1 week, and pure calcite after 2 weeks. The presence of organic material associated with the mineral was also identified and quantified. TRLFS was used to track the interaction and speciation of Eu³⁺ as a molecular probe with the mineral as a function of time. Initially, Eu³⁺ is incorporated into the vaterite phase, while during CaCO₃ phase transformation Eu³⁺ speciation changes resulting in several species incorporated in the calcite phase either substituting at the Ca²⁺ site or in a previously unidentified, low-symmetry site. Comparison of the biogenic precipitates to an abiotic sample shows mineral origin can affect Eu³⁺ speciation within the mineral.

How Do Radionuclides Accumulate in Marine Organisms? A Case Study of Europium with Aplysina cavernicola

In the ocean, complex interactions between natural and anthropogenic radionuclides, seawater, and diverse marine biota provide a unique window through which to examine ecosystem and trophic transfer mechanisms in cases of accidental dissemination. The nature of interaction between radionuclides, the marine environment, and marine species is therefore essential for better understanding transfer mechanisms from the hydrosphere to the biosphere. Although data pertaining to the rate of global transfer are often available, little is known regarding the mechanism of environmental transport and uptake of heavy radionuclides by marine species. Among marine species, sponges are immobile active filter feeders and have been identified as hyperaccumulators of several heavy metals. We have selected the Mediterranean sponge Aplysina cavernicola as a model species for this study. Actinide elements are not the only source of radioactive release in cases of civilian nuclear events; however, their physicochemical transfer mechanisms to marine species remain largely unknown. We have targeted europium(III) as a representative of the trivalent actinides such as americium or curium. To unravel biological uptake mechanisms of europium in A. cavernicola, we have combined radiometric (γ) measurements with spectroscopic (time-resolved laser-induced fluorescence spectroscopy, TRLIFS, and X-ray absorption near-edge structure, XANES) and imaging (transmission electron microscopy, TEM, and scanning transmission X-ray microscopy, STXM) techniques. We have observed that the colloids of NaEu(CO₃)₂·nH₂O formed in seawater are taken up by A. cavernicola with no evidence that lethal dose has been reached in our working conditions. Spectroscopic results suggest that there is no change of speciation during uptake. Finally, TEM and STXM images recorded at different locations across a sponge cross section, together with differential cell separation, indicate the presence of europium particles (around 200 nm) mainly located in the skeleton and toward the outer surface of the sponge.

Incorporation of Eu(III) into Calcite under Recrystallization conditions

The interaction of calcite with trivalent europium under recrystallization conditions was studied on the molecular level using site-selective time-resolved laser fluorescence spectroscopy (TRLFS). We conducted batch studies with a reaction time from seven days up to three years with three calcite powders, which differed in their specific surface area, recrystallization rates and impurities content. With increase of the recrystallization rate incorporation of Eu³⁺ occurs faster and its speciation comes to be dominated by one species with its excitation maximum at 578.8 nm, so far not identified during previous investigations of this process under growth and phase transformation conditions. A long lifetime of 3750 μs demonstrates complete loss of hydration, consequently Eu must have been incorporated into the bulk crystal. The results show a strong dependence of the incorporation kinetics on the recrystallization rate of the different calcites. Furthermore the investigation of the effect of different background electrolytes (NaCl and KCl) demonstrate that the incorporation process under recrystallization conditions strongly depends on the availability of Na⁺. These findings emphasize the different retention potential of calcite as a primary and secondary mineral e.g. in a nuclear waste disposal site.

An investigation of the interactions of Eu³⁺ and Am³⁺ with uranyl minerals: implications for the storage of spent nuclear fuel

The reaction of a number of uranyl minerals of the (oxy)hydroxide, phosphate and carbonate types with Eu(iii), as a surrogate for Am(iii), have been investigated. A photoluminescence study shows that Eu(iii) can interact with the uranyl minerals Ca[(UO2)6(O)4(OH)6]·8H2O (becquerelite) and A[UO2(CO3)3]·xH2O (A/x = K3Na/1, grimselite; CaNa2/6, andersonite; and Ca2/11, liebigite). For the minerals [(UO2)8(O)2(OH)12]·12H2O (schoepite), K2[(UO2)6(O)4(OH)6]·7H2O (compreignacite), A[(UO2)2(PO4)2]·8H2O (A = Ca, meta-autunite; Cu, meta-torbernite) and Cu[(UO2)2(SiO3OH)2]·6H2O (cuprosklodowskite) no Eu(iii) emission was observed, indicating no incorporation into, or sorption onto the structure. In the examples with Eu(3+) incorporation, sensitized emission is seen and the lifetimes, hydration numbers and quantum yields have been determined. Time Resolved Laser Induced Fluroescence Spectroscpoy (TRLFS) at 10 K have also been measured and the resolution enhancements at these temperatures allow further information to be derived on the sites of Eu(iii) incorporation. Infrared and Raman spectra are recorded, and SEM analysis show significant morphology changes and the substitution of particularly Ca(2+) by Eu(3+) ions. Therefore, Eu(3+) can substitute Ca(2+) in the interlayers of becquerelite and liebigite and in the structure of andersonite, whilst in grimselite only sodium is exchanged. These results have guided an investigation into the reactions with (241)Am on a tracer scale and results from gamma-spectrometry show that becquerelite, andersonite, grimselite, liebigite and compreignacite can include americium in the structure. Shifts in the U[double bond, length as m-dash]O and C-O Raman active bands are similar to that observed in the Eu(iii) analogues and Am(iii) photoluminescence measurements are also reported on these phases; the Am(3+) ion quenches the emission from the uranyl ion.

Using Eu(3+) as an atomic probe to investigate the local environment in LaPO4-GdPO4 monazite end-members

In the present study, we have investigated the luminescent properties of Eu(3+) as a dopant in a series of synthetic lanthanide phosphates from the monazite group. Systematic trends in the spectroscopic properties of Eu(3+) depending on the size of the host cation and the dopant to ligand distance have been observed. Our results show that the increasing match between host and dopant radii when going from Eu(3+)-doped LaPO4 toward the smaller GdPO4 monazite decreases both the full width at half maximum of the Eu(3+) excitation peak, as well as the (7)F2/(7)F1 emission band intensity ratio. The decreasing Ln⋯O bond distance within the LnPO4 series causes a systematic bathochromic shift of the Eu(3+) excitation peak, showing a linear dependence of both the host cation size and the Ln⋯O distance. The linear relationship can be used to predict the energy band gap for Eu(3+)-doped monazites for which no Eu(3+) luminescent data is available. Finally, mechanisms for metal-metal energy transfer between host and dopant lanthanides have been explored based on recorded luminescence lifetime data. Luminescence lifetime data for Eu(3+) incorporated in the various monazite hosts clearly indicated that the energy band gap between the guest ion emission transition and the host ion absorption transition can be correlated to the degree of quenching observed in these materials with otherwise identical geometries and chemistries.