Emission Spectra Of Eu3 Research Articles

Synthesis and spectroscopic investigations of trivalent europium-doped M2SiO5 (M = Y and Gd) nanophosphor for display applications

Synthesis of trivalent europium ion-doped Y2SiO5 (YSO) and Gd2SiO5 (GSO) was carried out via sol–gel combustion technique using organic fuel. The optical and structural properties of these phosphors were analyzed. The structural investigations of the samples were studied using X-ray diffraction (XRD), Fourier transformation infrared (FTIR) and transmission electron microscopy (TEM). XRD patterns show monoclinic crystal lattice (space group P21/c) for M2SiO5 (M = Y and Gd) host materials, irrespective of metals (Y and Gd) and change in temperature upto 1050 °C. The increased intensity of XRD peaks with rise in temperature indicates the increase in crystalline nature of the phosphors. FTIR bands at 880–1020 cm−1 confirm the presence of SiO4 tetrahedra with layered structure and support XRD results. TEM images depict the spherical nanoparticles with filled morphology, narrow size distribution and slightly agglomerated crystallites of the samples. The crystallite sizes of phosphors from TEM analysis are promising with that calculated by Scherer’s formula using XRD data. Energy-dispersive X-ray analysis (EDAX) shows the composition of elements present in small area of sample. The spectra show a number of peaks that belongs to various elements integrated with the host framework. The photoluminescence (PL) emission spectra of Eu3+-doped samples showed 5D0 → 7Fj (j = 1, 2 and 3) transitions under 393–394 nm excitation. Strong red emission corresponding to hypersensitive 5D0 → 7F2 transition (611 nm) suggested the presence of Eu3+ ions in a site having absence of centre of symmetry. Due to advantageous properties such as intense photoluminescence and high crystallinity these nanophosphors could possess potential applications in the mercury-free lighting sources and modern display devices.

Luminescence of Agrellite Specimen from the Kipawa River Locality

Using steady-state luminescence measurements, the luminescence spectra of Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Dy3+, Er3+ and Yb3+ for the agrellite sample from the Kipawa River region have been measured. The emission spectra of Eu3+ and Dy3+ next to those of Sm3+ and Pr3+ have been measured for characteristic excitation conditions. The most efficient luminescence activator in the studied sample was Ce3+. This ion was also a sensitizer of Pr3+, Sm3+, Eu3+, and Dy3+ luminescence.

Eu3+-doped fluoro-telluroborate glasses as red-emitting components for W-LEDs application

From 0.1 up to 2.5 mol% Eu3+-doped fluro-telluroborate glasses as red light-emitting components for white-light-emitting diodes (WLEDs) were investigated. Non-periodicity in the atomic arrangements was studied through the XRD pattern. The photoluminescence (PL) spectra were recorded under blue light (464 nm) excitation and analyzed. All the PL spectra exhibit an intense peak at 612 nm for 5D0 → 7F2 transition, revealing their red photoemission. Optimal PL emissions were achieved for 1.0 mol% Eu3+-doped sample. The CIE chromaticity coordinates for all the glasses (x = ~0.69, y = ~0.30) fall within the red color region. The J‒O parameters (Ω2, Ω4) were calculated following the emission spectra of Eu3+-doped samples and the intensity parameters (Ω2>Ω4), as well as the high asymmetry ratio (R/O), indicate the low ionicity in all the studied glasses. Using the J-O parameters, several radiative features like total emission transition probability (AT), branching ratios (radiative (βR) & experimental (βexp)), stimulated emission cross-section (σPE), gain bandwidth (σPE × λeff), and optical gain (σPE × τrad) were evaluated. All the luminescence decay curves fit well to non-exponential function and decay times were decreased at Eu3+ concentration >0.5 mol%. The evaluated σPE = 19.684 × 10−21 cm2, βexp = 0.759, τexp = 1.325 m s, minimum non-radiative relaxation, WNR = 296/s, and 60.78% of quantum efficiency (η) for 1.0 mol% Eu3+-doped glass for 5D0 → 7F2 transition indicates its promising features for red light-emitting optical devices and also as a red component in WLEDs.

Radiative and non-radiative characteristics of Ca9Bi(PO4)7:Eu3+ nano-phosphor for solid state lighting devices

Single-phased bright-red emitter Ca9Bi1–x(PO4)7:xEu3+ nanophosphor series was obtained by time-saving combustion-synthesis technique. The structural prototype for Ca9Bi(PO4)7 and Ca9Bi0.40(PO4)7:0.60Eu3+ were obtained by using the Rietveld refinement method, revealing a trigonal crystal system of R3c(161) space group symmetry. The values of the band-gap for maximum-fluorescent-concentration and pure host were determined to be 4.23 and 4.30 eV, respectively. The critical distance for energy migration (12.35 Å) and Dexter's exchange-profiling held the dipole/dipole (d–d) interactions responsible for the quenching process observed after optimum composition. The refractive index of the pure host (2.22) and the photoluminescent (PL) emission spectra of Eu3+-doped samples were used to work out Judd-Ofelt intensity parameters. The detailed photo-luminescent analysis provided the value of quantum efficiency, non-radiative and total radiative transition-rate for Ca9Bi0.40(PO4)7:0.60Eu3+ phosphor. Furthermore, various optical results, including the very high value of stimulated emission-cross-section (10.64), claim Ca9Bi0.40(PO4)7:0.60Eu3+ system as a very much promising candidate for the laser and solid-state lighting (SSL) devices.

Spectroscopic properties of antimony modified germanate glass doped with Eu3+ ions

In this work structural and luminescence properties of gallo-germanate glasses were investigated. The mentioned glass system was modified with barium and antimony oxides and doped with Eu3+ ions. The starting glass consisted of barium oxide as a modifier which was then gradually replaced by antimony oxide to form six glass samples. The gallo-germanate glass as a low-phonon host for RE (Rare Earths) ions is a promising material for optoelectronics. However, luminescence properties closely depend on material composition. For this reason, structural changes in studied materials were induced by changing its chemical composition and the luminescence properties were tested. The FT-IR (Fourier-Transform Infrared Spectroscopy) and the Raman spectra of studied glasses illustrate the tendency to increasing quantity of bridging oxygen connecting germanium ions and decreasing quantity of non-bridging oxygen along with antimony oxide addition. Simultaneously the BP (Boson Peak) measurements and emission spectra of Eu3+ ions show an increasing tendency to the examined glass structure ordering along with modifier oxide addition.

Phosphate glasses with high tantalum oxide contents: Thermal, structural and optical properties

Glasses in the binary system KPO3-Ta2O5 were prepared by the melt-quenching technique. Highly modified phosphate glasses with up to 40 mol% Ta2O5 were obtained. The samples were characterized by Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) analysis, Ultraviolet–Visible (UV–Vis) and infrared (IR) transmittance, Raman and luminescence spectroscopies. Thermal, structural and optical properties are strongly dependent of the tantalum oxide content. Thermal behavior and Raman data are in agreement with a progressive insertion of tantalum units in the phosphate network through P-O-Ta bonds. These bonds enhance the network connectivity due to TaO6 units cross-linking the linear phosphate chains. In addition, higher Ta2O5 contents in the glass network results in tantalum oxide-rich regions detected as Ta-O-Ta bridging bonds, apparently acting as crystallization nuclei. Emission spectra of Eu3+-doped glasses pointed out a decrease in the symmetry of the Eu3+ sites by increasing Ta2O5 content. A decrease in the excited state lifetimes was also identified due to the progressive Ta-rich environment around Eu3+ ion. Finally, photoluminescence quantum efficiency increases with tantalum insertion due to the reduction of local phonon energy around rare-earth ions. In this sense, high tantalum phosphate glasses are built up from TaOx polyhedra within the phosphate chains. The presence of TaOx clusters allows the improvement of optical and thermal properties and corroborates with the potential application of these materials photonic devices.

Unravelling the Complexities of Pseudocontact Shift Analysis in Lanthanide Coordination Complexes of Differing Symmetry.

In two closely related series of eight-coordinate lanthanide complexes, a switch in the sign of the dominant ligand field parameter and striking variations in the sign, amplitude and orientation of the main component of the magnetic susceptibility tensor as the Ln3+ ion is permuted conspire to mask modest changes in NMR paramagnetic shifts, but are evident in Yb EPR and Eu emission spectra.

Unravelling the Complexities of Pseudocontact Shift Analysis in Lanthanide Coordination Complexes of Differing Symmetry

AbstractIn two closely related series of eight‐coordinate lanthanide complexes, a switch in the sign of the dominant ligand field parameter and striking variations in the sign, amplitude and orientation of the main component of the magnetic susceptibility tensor as the Ln3+ ion is permuted conspire to mask modest changes in NMR paramagnetic shifts, but are evident in Yb EPR and Eu emission spectra.

Warm white light and colour tunable characteristics of Dy3+ co-doped with Eu3+ and Pr3+ zinc sodium bismuth borate glasses for solid state lighting applications

Present work reports the colour tunable characteristics of Dy3+- doped zinc sodium bismuth borate glasses with Eu3+ and Pr3+ co-dopants synthesized through melt quench technique. The absence of sharp peaks in the XRD confirmed the amorphous nature of co-doped glasses. Absorption peaks of Dy3+, Eu3+ and Pr3+ions are found in visible and NIR region of the spectrum. The optical band gap of the glasses were determined through absorption spectra. The excitation spectra exhibited various transitions of Dy3+, Eu3+ and Pr3+ ions in the UV and blue region of the spectrum. The emission spectra of Eu3+ and Pr3+co-doped glass showed blue, yellow and red emissions. Decay curves were measured to confirm the energy transfer processes between Dy3+→Eu3+ and Pr3+ ions. The Inokuti-Hirayama model was used to understand the nature of interaction between Dy3+→Eu3+ and Pr3+ ions during non-radiative energy transfer in the co-doped glasses. CIE chromaticity coordinates shifted from yellowish to orange-reddish region. The correlated colour temperature value of optimum glass was around 3800 K which further illustrates the application of co-doped glasses in indoor lighting under UV/blue light excitation.

Synthesis, structure, Hirshfeld surface analysis and photophysical studies of red emitting europium acetylacetonate complex incorporating a phenanthroline derivative

Two new octa-coordinated red emitting complexes of the type [Ln(acac)3(Br2-phen)] [acac: acetylacetonate, Br2-phen: 4,7-dibromo-1,10-phenanthroline, Ln: Sm(III) and Eu(III)] have been synthesized and characterized. Single crystal X-ray diffraction (SCXD) of [Eu(acac)3(Br2-phen)] and [Eu(acac)3(H2O)2](H2O) revealed distorted square antiprism structure for both complexes. 2D fingerprint plots and Hirshfeld surface analyses signify important interactions in crystal packing [H⋯H (72.2%), O⋯H/H⋯O (18.9%) and C⋯H/H⋯C (6.7%) contacts for [Eu(acac)3(H2O)2](H2O), while [Eu(acac)3(Br2-phen)] showed H⋯H (40.5%), Br⋯H/H⋯Br (12.9%) and O⋯H/H⋯O (6.5%)] contacts]. Photophysical measurements gave quantum yield (QLnL) of 1.1 and 13% with corresponding luminescence lifetime (τobs) of 38.76 ± 0.61 μs and 790 ± 1.53 μs for [Sm(acac)3(Br2-phen)] and [Eu(acac)3(Br2-phen)], respectively. We have further evaluated photophysical properties of [Eu(acac)3(Br2-phen)] theoretically from the optimized sparkle structure and steady-state emission spectrum of Eu(III) complex. The intramolecular energy transfer (WET) and back-energy transfer (WBT) rate predicted from the calculated singlet (S1) and triplet (T1) levels to the emissive 5D1 and 5D0 states for Eu(III) follow the path S0 → S1 → T1 → 5D1 → 5D0 → 7F0,4. The Eu(III) complex showed large stimulated emission cross-section (σ(0→2) = 1.27 × 10−20 cm2) similar to Nd-glass laser (1.6–4.5 × 10−20 cm2) and offers promise for high-power laser medium.

Absorption intensity analysis and emission properties KEu(PO3)4 and KEuxY1-x(PO3)4 crystals

Abstract Optical absorption, excitation and emission spectra of Eu3+ ions in stoichiometric KEu(PO3)4 and KEuxY1-x(PO3)4 crystals were investigated. Strong, red emissions of Eu3+ centered at 617 and 700 nm originates mainly from the 5D0 →7F2+7F4 transitions respectively. Judd-Ofelt intensity parameters for f-f transitions were derived from the emission spectra and also from the integrated absorption spectra. These parameters were used to calculate the radiative transition rates (AR), lifetimes (τR) and branching ratios β for 5D0 excited state of Eu3+. The calculated values of τR and β were compared with the measured values for 5D0 level. The 5D0 fluorescence decay time in pure KEu(PO3)4 was exponential and quite long, of 3.93 ms. The stimulated emission cross-sections σ were also evaluated for the 5D0 → 7FJ transitions for the first time in this system.

A development of new red phosphor based on europium doped as well as substituted Barium Lanthanum Aluminate (BaLaAlO4: Eu3+)

New red emitting Eu3+ doped and substituted BaLaAlO4 phosphor powders were synthesized by simple modified solid state reaction method. BaLaAlO4 crystal phase formation studied through powder X-ray diffraction (XRD) analysis. Fourier Transform - Infra Red (FT-IR) analysis was performed to study the formation of the host with respect to temperature increment and metal-oxygen bond vibrations of BaLaAlO4 host lattice. Morphology of the phosphor was appeared as irregular in shapes with agglomeration. Photoluminescence (PL) analysis was performed to study the PL excitation and emission characteristics of the phosphor. It dictates that synthesized phosphors exhibited a strong red emission at 626 nm. Substitution effect of Eu3+ in BaLaAlO4 with various compositions such as Ba(1-x)LaAlO4: Eux3+, BaLa(1-y)AlO4: Euy3+ and BaLaAl(1-z)O4: Euz3+ were studied for PL enhancement. Luminescence decay time of the phosphors was also determined. PL thermal quenching and Commission Internationale de l'Eclairage (CIE) chromaticity analysis were carried out to find thermal stability and colour purity of the phosphor sample respectively. The Judd- Ofelt parameters (Ω2 & Ω4) obtained from the emission spectra of Eu3+ ions in BaLaAlO4 host lattice were evaluated and discussed.

Investigation of structural, optical and electrical properties of Sr2SnO4, Sr1.99Eu0.01SnO4 and Sr2Sn0.99Eu0.01O4 Ruddlesden Popper oxide

Structural, electrical and optical properties of samples have been reported in this paper. The samples with compositions Sr2SnO4, Sr1.99Eu0.01SnO4 and Sr2Sn0.99Eu0.01O4 are prepared by solid state ceramic route followed by calcination at temperature 1000 °C for 8 h. Rietveld refinement of powder x-ray diffraction (XRD) data showed tetragonal structure in all samples with space group (I4/mmm). X-ray photoelectron spectroscopy (XPS) studies indicate the presence of Sn in Sn4+ and Sn2+ state in both the samples. The electrical conductivity of the sample follows universal johnscher’s law.‘’. Temperature dependent electrical conductivity shows Arrhenius type charge transport in samples Sr2SnO4, Sr1.99Eu0.01SnO4 and Sr2Sn0.99Eu0.01O4 with activation energy 0.16, 0.17, 0.16 eV respectively. Conduction in these sample occurs via electron hopping through the multivalent state of Sn, Conductivity spectra obtained at different temperature scaled by Ghosh Scaling perfectly follows time temperature superposition principle (TTSP). The presence of Eu is further probed by photoluminescence (PL) spectroscopy in which emission spectra of Eu3+ for both the samples show intense emission peak at 577, 595 and 612 nm assigned to transitions from 5D0 → 7FJ (J = 0, 1, 2, 3) levels of Eu3+. Higher the value of conductivity σdc and integrated area of emission peak for Sr1.99Eu0.01SnO4 is making it more multifunctional than Sr2Sn0.99Eu0.01O4.

Experimental and Ab Initio Study on the Intensitiesof f–f Transitions for the Molecular Eu(III)‐DOTP System

AbstractThe experimental f‐f transition intensities, derived from UV‐vis absorption and emission spectra of Eu(III)‐DOTP systems (where DOTP is 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetrayl)tetrakis‐(methylene))‐tetraphosphonate anion) in [C(NH2)3]5[Eu(DOTP)]⋅12.5H2O and K5[Eu(DOTP)]⋅11H2O crystals and in solution, were analyzed in terms of Judd‐Ofelt theory. A non standard approach was used to calculate Ωλ parameters by including both the absorption 7F0→2S+1LJ and emission 5D0→7FJ bands in the calculation procedure. The f‐f transition intensities of two {K4[Eu(DOTP)]}– clusters representing the two different forms of Eu(III)‐DOTP complex in K5[Eu(DOTP)]⋅11H2O crystal, calculated within ab initio approach were compared with the experimental counterparts. The theoretical results provided a deeper insight into the nature of the hypersensitive and highly‐forbidden f‐f transitions for system under study. The possible improvements of the theoretical approach are discussed in the light of the known mechanisms contributing to the intensities of f‐f transitions. Finally the solution structure of the [Eu(DOTP)]5– complex was examined by complementary techniques including temperature dependent UV‐vis absorption and time‐resolved emission spectroscopy. This enabled us to show that the structure of the [Eu(DOTP)]5– complex in solution is practically the same as those in crystals. In particular it means that there are no water molecules coordinated to the central Eu(III) cation. The observed decrease of luminescence integral intensities of the 5D0→7FJ bands at elevated temperatures of solution, usually assigned to a chemical reaction, is brought about actually by the changes of solution viscosity.

Luminescence and Cationic-Size-Driven Site Selection of Eu3+ and Ce3+ Ions in Ca8Mg(SiO4)4Cl2.

In this work, the morphology, composition, crystal, and electronic structure of Ca8Mg(SiO4)4Cl2 (CMSOC) prepared by a high-temperature solid-state reaction technique are characterized first. To investigate the site occupancies of Eu3+ and Ce3+ in CMSOC, the emission spectra under well-chosen wavelength excitations and the corresponding excitation spectra by monitoring of the specific wavelength emissions are measured in detail for singly doped samples with different concentrations. Two kinds of Eu3+ or Ce3+ luminescence spectra are found. On the basis of the chemical environments of two Ca2+ sites and dielectric chemical bond theory, the sites of these two kinds of Eu3+ and Ce3+ luminescence spectra are respectively assigned. Because energy transfer between the two types of luminescent centers, concentration-dependent emission-wavelength shifting, and luminescence concentration quenching are negligible, the emission spectra of Eu3+ and Ce3+ give us a hint of their occupation preferences on two Ca2+ sites. The results indicate that, with an increase of the doping concentration, the Eu3+ ions with smaller cationic size show an occupation preference on the smaller Ca2+(1) sites, but the Ce3+ ions with larger cationic size are inclined to enter the larger Ca2+(2) sites. These opposite occupation preferences of Eu3+ and Ce3+ in CMSOC are thought to be the cationic-size-driven site selection.

Aggregation of Rare Earth Coordination Complexes in Solution Studied by Paramagnetic and DOSY NMR.

The degree of aggregation of neutral, 9-coordinate rare earth coordination complexes has been shown to affect their ligand field, as revealed by diffusion-ordered NMR spectroscopy (DOSY-NMR) measurements on Y(III) complexes, paramagnetic NMR analyses of Yb and Tb analogues and emission spectral studies with the EuIII systems. In non-polar media a lipophilic tris-isopropyl complex, [Ln.L2 ] tends to aggregate in chloroform and dichloromethane giving rise to oligomers, whereas in acetic and trifluoroacetic acid the more polar parent complex, [Ln.L1 ], also aggregates, profoundly affecting the pseudocontact shift and the form of the Eu emission spectrum. Such behaviour has important implications in the design of responsive spectral probes.

JOES: An application software for Judd-Ofelt analysis from Eu3+ emission spectra

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: TiO2:Eu3+, ZrO2:Eu3+ and Nb2O5:Eu3+. We wish to give to the researchers this theoretical tool which can make the calculations easier, faster and more reliable.

Photoluminescence properties of red emitting Ba3Bi2(PO4)4:Eu3+ phosphor for WLEDs applications

The Eu3+ activated Ba3Bi2(PO4)4 red emitting phosphors were prepared by the conventional solid state reaction method. The phase identification of the phosphors was characterized by using the powder X-ray diffraction (PXRD) patterns. The high resolution scanning electron microscopy (HRSEM) and the photoluminescence properties of Ba3Bi2(PO4)4:Eu3+ phosphors were investigated. Exciting the phosphor at 395 nm (7F0 → 5L6) or 466 nm (7F0 → 5D2) yielded emission bands at 579, 592, 611, 651 and 698 nm, attributed to the various transitions (5D0→7FJ (J = 0,1, 2, 3, and 4)) of the Eu3+ ions in the same order. The dominant emission band at 611 nm was the well known hypersensitive red emission (5D0 → 7F2). The excitation spectrum for the 611 nm emission of the optimized phosphor (for which the maximum luminescence was observed) exhibited several bands peaking at 363, 384, 395, 417 and 466 nm. The observed excitation and the emission spectra could be attributed to the characteristic intraconfigurational 4f–4f transitions of Eu3+ ions. The Judd-Ofelt (J-O) intensity parameters (Ω2 and Ω4) were determined from the emission spectra of Eu3+ ions. The luminescence lifetime measurments were made. The temperature dependent luminescence spectra of Ba3Bi2(PO4)4:Eu3+ under the excitation of 395 nm were studied. The luminescence quantum efficiency was calculated. In addition, the Commission International del`Eclairagethe (CIE) chromaticity coordinates of Ba3Bi2(PO4)4:Eu3+ phosphor was found to be located in the red region (0.6381,0.3615) when excited at 395 nm. From these results it was noted that the Eu3+ activated Ba3Bi2(PO4)4 phosphor could be used as a red emitting phosphor for the near-UV excited WLEDs.

Spectroscopic properties and Judd–Ofelt analysis of Eu3+ in Y4Al2O9 crystals

Optical absorption, excitation and emission spectra of Eu3+ ions in Y4Al2O9 were investigated. Judd-Ofelt intensity parameters for f-f transitions were derived from the emission spectra and also from the integrated absorption spectra. These parameters were used to calculate the total spontaneous emission probabilities (AR), lifetimes (τR) and branching ratios (βR) for 5D0 excited state of Eu3+. The calculated values of τR and βR are compared with the measured values for 5D0 level. The stimulated emission cross-sections σ were also evaluated for the 5D0 → 7FJ transitions for the first time in this system.

Optical analysis of RE3+ (RE=Eu, Tb): CdO-PbO-B2O3-AlF3 glasses

In this article, we report on the photoluminescence properties of cadmium lead boro aluminum fluoride (CdPbBAlF) glasses as a function of various doping concentrations of Eu3+ and Tb3+ ions. The emission spectra of Eu3+: CdPbBAlF glasses have shown bright reddish emission at 613nm (5D0→7F2) under the excitation at 395nm and Tb3+: CdPbBAlF glasses exhibited intense green emission at 545nm (5D4→7F5) with the excitation at 379nm. The luminescence quenching behavior of the prepared glasses as a function of the doping molar concentration of Eu3+ and Tb3+ ions was analyzed, which could be useful for optimizing the potential composition towards the novel optical applications. Energy level diagram representing the emission lines and decay curves of the prominent emission transitions at 613nm, 545nm of Eu3+ and Tb3+: CdPbBAlF glasses have been presented.