Fluorescence Spectra Of Eu3 Research Articles

Luminescent solar concentrator employing rare earth complex with zero self-absorption loss

Luminescent solar concentrator (LSC) employing Eu(TTA)3(TPPO)2 (europium tris(2-thenoyl trifluoro acetonate)-di(triphenylphosphine oxide)) was fabricated in our work firstly, and then its current–voltage (I–V) performance under AM1.5G radiation with different radiation area were measured and compared with that of LSC employing dye. As there is no overlap between absorption spectrum and fluorescence spectrum of Eu(TTA)3(TPPO)2, it is found that the power conversion efficiency of LSC employing Eu(TTA)3(TPPO)2 decreases ten times slower than that of LSC employing dye reported with the increment of radiation area under AM1.5G. To accurately characterize the zero self-absorption loss of LSC employing rare earth complex more, external quantum efficiency (EQE) was also measured and simulated theoretically. When experiment data is compared with theoretical simulation, the measured EQE data at 380 nm is found to well coincide with theoretical result by taking host absorption loss into consideration. And the conclusion could be drawn that rare earth complex obviously shows zero self-absorption loss in use of LSC system and is proposed as a potential candidate for increasing the LSC efficiency. 2011 Elsevier Ltd. All rights reserved.

Disorder effects in the fluorescence spectra of Eu3+ in langatate (La3Ga5.5Ta0.5O14) crystals

The nature of luminescence centers formed by Eu3+ in the partially disordered crystal langatate (La3Ga5.5Ta0.5O14) is investigated using fluorescence spectroscopy. In the low-temperature fluorescence spectra three nonequivalent luminescent centers can be evidenced. This fact can be explained considering the perturbations induced at the Eu3+ site by the nonequivalent configurations produced by Ga3+ and Ta5+ randomly placed in the nearest two octahedral positions.

Terminal group effects on the fluorescence spectra of Eu(III) nitrate complexes with a family of amide-based 1,10-phenanthroline derivatives

Four ligands 1,10-phenanthroline-5,6-bis( N, N-dibenzyl-1′-oxopropylamide) (L a) 1,10-phenanthroline-5,6-bis( N-methyl-N-benzyl-1′-oxopropylamide) (L b) 1,10-phenanthroline-5,6-bis(N-benzyl-1′-oxopropylamide) (L c) and 1,10-phenanthroline-5,6-bis( N, N-diethyl-1′-oxopropylamide) (L d), and their lanthanide(III) (La and Eu) complexes were synthesized. The complexes were characterized by elemental analysis, IR, fluorescence spectroscopy and conductivity. The lanthanide atoms are coordinated by O atoms from C=O, Ar–O –C and N atoms from phen With the difference of the ligands, the fluorescent intensities of the Eu(III) complexes vary regularly in the THF solution. Some factors that influence the fluorescent intensity were discussed.

Enhanced blue-violet and ultraviolet fluorescence from Eu 3+ doped silver colloids

Fluorescence spectra of Eu 3+ ions and silver colloid containing Eu 3+ have been recorded and analysed at room temperature. For solution containing Eu 3+, three blue-ultraviolet emission peaks are observed at 362, 380 and 420 nm, respectively, when the corresponding excitation wavelength is at 250–300 nm. When silver colloids were added to the solution containing Eu 3+, all these fluorescence peaks were enhanced about 10 times. We believe that these increased emission are due to the intense 7F 0 → 5H 6 transitions in Eu 3+ owing to the fluorescence at 315 nm from silver nanoparticles.

Structural, optical and non-linear investigation of Eu3+: Al(NO3)3-SiO2 sol-gel glass

Optical absorption and fluorescence spectra of Eu3+ ions in Al(NO3)3-SiO2 sol-gel glass have been investigated using the Judd- Ofelt theory. JO intensity parameters (ω λ ) and subsequent radiative properties for5 D 0 ↔7 F 1,2,4,6 transitions are determined. The lifetime (τr) of5 D 0 state is computed and along with JO parameters are compared with their corresponding values in other glasses prepared by conventional technique. A structural analysis, using IR and XRD spectra and non- linear parametrization of the silica gel glass is carried out. The study reveals the glass to be a very good third order non- linear amorphous optical material.

Structural, optical and non-linear investigation of Eu3+ ions in sol–gel silicate glass

Optical absorption and fluorescence spectra of Eu 3+ ions in Al(NO 3 ) 3 –SiO 2 sol–gel glass have been investigated using the Judd–Ofelt theory. JO intensity parameters (Ω λ ) and subsequent radiative properties for 5 D 0 → 7 F 1,2,4,6 transitions are determined. The lifetime ( T R ) of 5 D 0 state is computed and along with the JO parameters are compared with their corresponding values in other glasses prepared by conventional technique. A structural analysis, using IR and XRD spectra and non-linear parameterization of the silica gel glass is carried out.

The luminescence of Eu3+ ion in Ca2Al2SiO7

Ca2Al2SiO7:Eu3+ was prepared by the sol–gel method. Through the emission spectrum of Eu3+ ion, the fluorescence parameters such as Ωi (i=2,4) and radiative transition probabilities of 5D0–7Fj were calculated. The Pb2+ ion with bigger radius has an effect on the fluorescence spectra of Eu3+ which can be explained by the structure of the matrix. Simultaneously, the energy transfers between mercury-like ions (Pb2+ and Bi3+) and Eu3+ ion were observed. The 5D4 and 5D2 energy levels of Eu3+ are the resonance ones for Pb2+ ion.

Optical studies of Eu 3+ ions doped in tellurite glass

Absorption and fluorescence spectra of Eu 3+ ions doped in a tellurite glass have been recorded and analysed. Judd–Ofelt analysis has been done in order to calculate the different optical parameters such as oscillator strength, Judd–Ofelt intensity parameters, stimulated emission cross-section, transition probability, branching ratio, radiative lifetime, etc. Lifetime measurements of the 5D 0 level as a function of Eu 3+ concentration have been used to explore the concentration quenching process. The mechanism of quenching is found to be of a dipole–dipole type.

Ferroelectric Properties and Second Harmonic Intensities of Stillwellite-Type (La,Ln)BGeO5 Crystallized Glasses

Glasses with compositions corresponding to stillwellite-type (La,Ln)BGeO5 (Ln: Nd, Gd, Eu and Tm) crystalline phases have been prepared, and the effect of lanthanide substitutions on ferroelectric properties and second harmonic (SH) intensities of stillwellite-type crystalline phases formed by crystallization of glasses has been examined. The substitution of Ln3+ for La3+ ions in the LaBGeO5 phase has been confirmed from the results of X-ray diffraction (XRD) analysis and fluorescence spectra of Eu3+ ions. The substitution of Ln3+ for La3+ ions causes a decrease not only in the lattice constants but also in the a/c axis ratio. The amount of substitutions depends on the Ln3+ ionic radius. The Curie temperature of crystallized glasses increases almost linearly with decreasing mean ionic radius of lanthanides estimated from the composition of base glasses. A similar trend is observed in the SH intensity for crystallized glasses (powdered form), indicating the presence of a close relationship between Curie temperature and SH intensity. It is proposed from Raman spectra that the enhancement of SH intensities is caused by the change in the arrangements of BO4 and GeO4 tetrahedra in the (La,Ln)BGeO5 crystals due to the substitution of Ln3+ ions having stronger Ln3+–O bonds. A clear second harmonic generation is observed in transparent surface crystallized glasses of the Nd2O3- or Gd2O3-substituted system.

Optical properties of LnPO4:Eu3+ (Ln=Y, La and Gd) powder phosphors

Abstract The synthesis, single and dual host compositional effects on the fluorescence spectra of Eu3+-doped YPO 4 , LaPO 4 , GdPO 4 , ( La , Gd ) PO 4 , (La,Y)PO4 and (Gd,Y)PO4 powder phosphors are studied. From the fluorescence spectra the emission transition 5 D 0 → 7 F 1 has been found to be more prominent over the normal red emission transition ( 5 D 0 → 7 F 2 ) . Under a UV-source these phosphors have been fluorescent in orange–red color. The observed absorption frequencies (ν,cm−1) are reported from the measured FT-IR spectra. Scanning electron microscopic investigations are carried out to understand the surface morphological features and the grain size. The room temperature lifetime measurements are made for the two emission transitions ( 5 D 0 → 7 F 1,2 ) of all these phosphors. Qualitative analysis of the elements (Y, La, Gd, Eu, O and P) has been carried out by the SEM/EDAX technique.

Effect of hydrostatic pressure on the free-ion parameters and the crystal-field strength for YOCl:Eu 3+

The fluorescence spectra of Eu 3+ in YOCl:Eu 3+ were measured under pressure up to 10.3 GPa at room temperature. The pressure dependence of the crystal-field levels of the 7F 0–4 and 5D 0–2 multiplets for the Eu 3+ ion was determined from the spectra. From the simulations of the experimental data, the free-ion parameters F 2 and ζ, the crystal-field parameters B k q and the crystal-field strength parameter S t were obtained at various pressures. The result of the simulation shows that the crystal-field strength increases with pressurization, which is contrary to the results of its isomorphic compounds, e.g. LaOCl and LaOBr doped with Eu 3+. The electrostatic repulsion and the spin–orbit coupling interactions of 4f electrons decrease with increasing pressure. The central-field covalency mechanism and the symmetry-restricted covalency mechanism play a leading role in the relative reductions of ζ and F 2, respectively.

Fluorescence spectra of Eu 3+-doped LnVO 4 (Ln = La and Y) powder phosphors

The fluorescence properties of Eu 3+-doped LaVO 4, (La 0.75,Y 0.25)VO 4, (La 0.5,Y 0.5)VO 4, (La 0.25,Y 0.75)VO 4, and YVO 4 powder phosphors are reported. The phase purity was checked by XRD and FT-IR spectra. The values of relative fluorescence intensity ratios (R) and color coordinates (X̄,Ȳ) were found to increase significantly with an increase in the yttrium concentration. Both thermal analysis and scanning electron microscopy (SEM) studies were carried out to characterize the samples.

Fluorescence spectra of Eu 3+ and Tb 3+-doped lanthanide oxychloride powder phosphors

The fluorescence spectra of Eu 3+ and Tb 3+-doped YOCl, LaOCl, GdOCl, (La,Gd)OCl, (La,Y)OCl and (Gd,Y)OCl powder phosphors are reported and they are analysed by evaluating the colour coordinates ( X ̄ , Y ̄ ) and also the relative fluorescence intensity ratios ( R). The Eu 3+ : phosphors have displayed bright red emission ( 5D 0 → 7F 2) and Tb 3+ : phosphors green emission ( 5D 4 → 7F 5) under an UV source.

Fluorescence spectra of Eu3+-doped lanthanide oxybromide-based powder phosphors

This paper reports the fluorescence properties of a new series of Eu3+-doped powder phosphors based on GdOBr, LaOBr and YOBr. A bright red emission (5D0→7F2) was observed from all of the powder phosphors under a UV source and this situation was confirmed by fitting the colour coordinates (X̄, Ȳ) in the CIE chromaticity diagram. The relative fluorescence intensity ratios for the different measured emission levels were also evaluated in order to examine the host matrix compositional effects on the fluorescence behaviours. The best fluorescent performance was observed from (Gd0.8, Y0.2)OBr in the case of a dual lanthanide oxybromide host and from LaOBr in the case of a single lanthanum oxybromide host. For the measured fluorescent transitions, the stimulated emission cross sections (σEp cm2) were also calculated. The (Gd0.8, Y0.2)OBr, and LaOBr powder phosphors could be suggested as two promising materials, among these studied, for red colour emission and for use in certain electronic systems.

Effect of pressure on electron state of Eu 3+ in Gd 2O 2S

The fluorescence spectra of Eu 3+ in Gd 2O 2S have been measured at room temperature and under pressures within the range of 0–14.8 GPa. The crystal-field levels of the 7F 0–6 and 5D 0–2 multiplets of the Eu 3+ ion have been determined at different pressures. With increasing pressure the crystal-field splittings of the 7F 2–5 and 5D 2 multiplets increase; however, the splittings of 7F 1 and 5D 1 decrease. The crystal-field parameters B k q and the crystal-field strength parameter S t versus B k q were also determined at different pressures. In the pressure range up to 14.8 GPa, S t increases by 11%. Under pressure, the barycenters of the 7F 1–2 and 5D 0–2 multiplets descend, the Slater parameter F 2 and the spin-orbit coupling parameter ζ reduce. The symmetry-restricted covalency mechanism plays a main role in the reduction of F 2 and ζ.

Photoluminescence of Eu3+ ion doped phosphate ceramics

Phosphate ceramics doped with Eu3+ ions were synthesized through sol-gel process. The fluorescence spectra of Eu3+ as a function of firing temperature, dopant concentration, composition, and structure of the matrices were investigated. The gels synthesized by the reaction of P2O5 with tetraethoxy silane or titanium tetraethoxide (Ti(OEt)4) and EuCl3⋅6H2O as the dopant were fired in air from the temperature range 200–900 °C to form P–Si or P–Ti crystalline phases. The crystal structure was examined by powder x-ray diffractometry. Si5O(PO4)6 was the only crystalline phase for the P–Si system. The amount of doping Eu3+ varied from 1 up to 10 at %, and no obvious concentration quenching was observed in the concentration range. It was found that the phosphosilicates gave stronger fluorescence emission than the phosphotitanates. For both systems, the intensity of Eu3+ emission increased with higher firing temperatures. For the P–Si system, the emission intensity increased with greater amounts of phosphorus, while the emission intensity did not change with the variation of composition in the P–Ti system.

Preparation and fluorescence properties of nanocomposites of amorphous silica glasses doped with lanthanide(III) benzoates

Lanthanide(III) benzoate complexes are decomposed by a few drops of HCl and, thus, cannot be doped in amorphous silica glasses prepared by the acidic (HCl) hydrolysis of tetraethoxysilane (TEOS). This work presents a novel technique of homogeneous doping these complexes in silica gel glasses. Eu(III) (or Tb(III)) and benzoic acid are co-introduced in sol-gel precursor solutions with suitable pH. The nano-scale Eu(III) (or Tb(III)) benzoate complexes are confirmed to form in amorphous silica glass through controlled gelation and drying. The fluorescence spectra of Eu(III) (or Tb(III)) in nanocomposites and the energy transfer efficiencies between Eu(III) (or Tb(III)) and benzoate are studied.

ChemInform Abstract: Fluorescence Spectra of Eu(II) in Borate and Aluminate Glasses.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Fluorescence Spectra of Eu(II) in Borate and Aluminate Glasses

Abstract The fluorescence and 151Eu Mössbauer spectra have been obtained for alkali borate, alkaline earth borate and rare-earth aluminate glasses containing Eu2+ ions. The Mössbauer spectra indicate that about 70 to 80% of the europium ions are present as Eu2+ ions in the borate glasses. As for the aluminate glasses, almost all of the europium ions are present as Eu2+ ions. The fluorescence spectra due to the 4f65d1 → 4f7 transition of the Eu2+ ion have been observed under excitation with UV radiation. There exists an empirical relationship that the emission energy decreases monotonically with an increase in the theoretical optical basicity of glass, irrespective of the glass systems. This relationship is explained in terms of simple crystal field theory by assuming that the splitting of the 5d levels mainly determines the emission energy of the Eu2+ ions. This empirical relationship also indicates that Eu2+ ions are distributed rather homogeneously in the present borate and aluminate glasses.

Influence of hydrostatic pressure upon the energy level scheme of Eu3+ in an La2O2S crystal

The fluorescence spectra of Eu3+ in an La2O2S crystal have been measured at room temperature and under hydrostatic pressures up to 13 GPa. The pressure dependence of the energy levels of Eu3+ in La2O2S has been determined. The observed crystal-field levels shift upwards or downwards with increasing pressure and undergo a distinct change in shift rates at about 10 GPa. The relative shift rates of the observed centroids of 5D0-2 multiplets are about the same. Simulations of the observed energy levels of Eu3+ in Y2O2S crystals have also been carried out in order to make a comparison between the results for Y2O2S:Eu3+ and those for La2O2S:Eu3+. Of the six crystal-field parameters, only B02 shows a somewhat puzzling change with increasing pressure and decreasing internuclear distances due to different isomorphous hosts. In the pressure range up to 13 GPa, the Slater parameters F2, F4 and F6 show a decrease of 0.38(9)%, 0.38(0)% and 0.38(3)%, respectively; the spin-orbit coupling parameters zeta decreases by 0.20%. In order to understand the regular decrease in the 5D0-2 multiplets with increasing pressure, the authors have inspected the calculated free-ion energy levels under different pressures and found that the energy E of any excited level can be related to pressure P by E=E0(1-cP), in which c=2.90(+or-0.15)*10-4 GPa-1.