Luminescence Properties Of Eu3 Research Articles

Luminescence properties of Eu3+ complexes based on macrocyclic ligands and its colorimetric analysis for white warm phosphor

Luminescence properties of Eu3+ complexes based on macrocyclic ligands and its colorimetric analysis for white warm phosphor

“Turn-on” Eu(III) chemosensory polymer materials for ammonia and amines detection: Experimental and molecular modeling study

Polymer films doped by Eu(III) complexes are promising candidates for the development of luminescent chemosensors. Here, luminescent properties of Eu(III) carboxylate dibenzoylmethanates in interaction with ammonia and amine vapors have been studied. Quantitative measurements of the optical response showed that with an increase of the analyte concentration in the range of 3–330 ppm, an increase in the luminescence intensity of europium(III) is observed. The reversibility of the luminescent response is established. Quantum chemical calculations showed that ammonia and amine molecules enter not in the Eu(III) coordination sphere, but forms hydrogen bonds between analyte molecules and carbonyl groups of the dibenzoylmethanate ion. Moreover, analyte changes ligand coordination mode: there occur the transformation from tridentate-bridging-cyclic coordination of carboxyl groups to bidentate-bridging which leads to decreasing in the efficiency of cross-relaxation of lanthanide ions. The obtained “turn-on” chemosensory polymer materials are promising for environmental monitoring and food safety testing.

Luminescence properties of Eu3+-doped potassium-gadolinium-phosphate glasses

Eu2O3-doped K2O-Gd2O3-P2O5 glasses were fabricated using the melt-quenching technique. The result indicates that the glasses' density and refractive index increase while the molar volume decreases from 0.05 to 0.5 mol% and then increases from 0.5 to 2 mol% with increased Eu2O3 concentration. The absorption spectra in the UV-Vis and NIR regions exhibit an energy transition from a ground state to possible excited states for 7F0 → 5K5, 7F0 → 3P0, 7F1 → 5G2, 7F0 → 5L6, 7F1 → 5D3, 7F0 → 5D2, 7F1 → 5D1 and 7F0 → 7F6, and 7F1 → 7F6. The luminescence characteristics were examined by photoluminescence (PL) and radioluminescence (RL). Both PL and RL confirmed that the optimum value at 2 mol% of Eu2O3 concentration. Similarly, the luminescence efficiency of 2 mol% Eu2O3 concentration compared with the BGO crystal equals 16.77%. As the concentration of Eu2O3 increased, the experimental decay curve dropped while the energy transfers efficiency (ɳET) and the energy transfer parameter (Q) raised. Interestingly, the CIE of emission spectra under 393 nm (UV lamp) were reddish orange (0.64, 0.35). The branching ratio (βR) was most significant at 612 nm, and the JO parameter trend was Ω2 > Ω6 > Ω4. Furthermore, all characterizations confirm its applicability in optical display devices.

Influence of P2O5 addition on glass structure and luminescent properties of Eu3+ ions in SiO2–CaO particles of bioactive glass

Influence of P2O5 addition on glass structure and luminescent properties of Eu3+ ions in SiO2–CaO particles of bioactive glass

A comparative study of spectral and luminescent properties of Eu3+-doped cation-deficient perovskite phosphors

Eu3+ is not only a major red-emitting activator, but also an excellent spectral probe ion. This work reports the Eu3+-sites and luminescence in the cation-deficient perovskite tungstates, A-site deficient SrLa2(Mg2W2)O12 [Sr1/2□1/2La(MgW)O6] and B-site deficient Sr2La2(MgW2)O12 [SrLa(Mg1/2□1/2W)O6]. The 7F0→5D0 excitation spectra of Eu3+ activators in two lattices were measured via pulsed dye laser. In SrLa2(Mg2W2)O12:Eu3+, there is only one 7F0→5D0 transition, which could be related to the Eu3+ center on La3+ sites; while, two 7F0→5D0 transitions in Sr2La2(MgW2)O12 indicate Eu3+ ions occupy Sr2+ in addition to La3+, resulting in the luminescent centers related to heterovalent substitution defects. The different Eu3+ sites make two phosphors exhibit different red luminescence properties. SrLa2(Mg2W2)O12:Eu3+ shows higher luminescent efficiency and thermal quenching due to its regular distribution of the activators resulting in lower dispersion losses of the energy transfer. The experimental results show that rare earth ions occupy different crystallographic positions in A-site and B-site deficient perovskite oxides, and this microstructure can be important for the corresponding luminescent properties.

Effect of thermal poling in sodium tantalum phosphate glass-ceramics

Eu3+-doped sodium tantalum phosphate glass-ceramics containing bronze -like perovskite crystalline phase Na2Ta8O21 were obtained with different crystalline states (degree of crystallinity and average crystallite size) by a suitable control of the heat-treatment time and temperature of the precursor glass. Luminescence properties of Eu3+ in these materials are in agreement with a progressive insertion of the rare earth ions in the sodium tantalate Na2Ta8O21 phase, as probed by a clear decrease of the intensity ratio between transitions [5D0 →] 7F2/7F1 and narrowing of characteristic emission bands. Thermal poling insights were performed on these glassy and glass-ceramic materials and the experimental conditions had to be carefully optimized in the glass-ceramics to avoid electrical sparks and sample break associated with dielectric breakdown of the samples. Suitable and stable thermal poling treatments could be performed at 250 °C and 900 V under N2 atmosphere on both glass and glass-ceramics. These first insights pointed out a lower migration kinetic of sodium ions when compared to the precursor glass as well as a lower content of depleted ions, since part of sodium is supposed to be “frozen” inside the crystalline phase in glass-ceramics. Despite these lower kinetic poling conditions, a poled sodium depleted layer whose thickness depends on the poling time was successfully formed at the anode side. Reflectance infrared spectroscopy was also used to investigate the structural changes in the poled layer. These IR data pointed out that structural changes induced by thermal poling are mainly promoted in the phosphate network rather than tantalate units in both glass and glass-ceramics in agreement with a selective sodium migration from the remaining glassy phase. Macroscopic induced SHG measured by the Maker fringes technique is also consistent with the EFISH model and quantitative simulations of these data allowed to estimate second order nonlinear optical susceptibilities χ(2) ten to twenty times lower in the glass-ceramics than in the precursor glass. Such electric behavior is discussed in terms of dielectric properties of heterogeneous materials and interfacial polarization mechanisms between crystallites and glassy phase.

Cation substitution induced structural phase transitions and luminescence properties of Eu3+-doped A2LaNbO6 (A = Ba, Sr, and Ca) double perovskite

Recently, double perovskites oxides have emerged as a prominence in the luminescence research, attributed to their adaptable structure, diverse chemical compositions, and stability. In this work, we investigated intricate relationship between cation substitution-induced structural modifications and the luminescent properties of Eu3+ doped A2LaNbO6, where A represents Ba, Sr, and Ca. The structural transitions in the Eu3+-doped A2LaNbO6 system were identified through comprehensive structural analysis techniques, including X-ray diffraction and Rietveld refinement. Under both photo- and cathode-excitations, the emission properties of Eu3+ exhibited marked enhancements as the structural deformations increased. Particularly intriguing were the anomalies in emission intensities and distribution of emission spectra occurring near the structural transition. Furthermore, we explored the Eu3+ doping dependence of the structural and emission properties in Ca2LaNbO6. Notably, the photoluminescence quantum yield reached a fairly high value of 83% under 465 nm photoexcitation at the Eu3+ concentration of 0.5. Additionally, we demonstrated that integration of Eu3+-doped Ca2LaNbO6 into phosphor-based white light emitting diodes (WLEDs) lead to improvements in the correlated color temperature of WLEDs.

Size-Control Synthesis and Luminescence Properties of Eu(III) Coordination Particles

Size-Control Synthesis and Luminescence Properties of Eu(III) Coordination Particles

Effect of Al2O3/SiO2 ratio on the structure and luminescence properties of Eu3+/Yb3+ co-doped Na2O–CaO–SiO2–Al2O3–ZnO–F glasses

The Eu3+/Yb3+ co-doped Na2O–CaO–SiO2–Al2O3–ZnO–F glasses were prepared. Various Al2O3/SiO2 ratios were used and their impact on the structure and optical properties of the glasses was examined. The results indicate that as the content of Al2O3 increases, the propensity for precipitation in the glass intensifies, while its thermal stability diminishes. The transmission spectra reveal that the incorporation of Al2O3 causes a shift towards longer wavelengths in the UV cut-off point of the glasses, which can be attributed to the alteration of the glass's network structure. Consequently, there is an increase in the amount of non-bridging oxygens present, ultimately resulting in a reduction of the optical bandgap. The analysis of luminescent properties suggests that as the Al2O3/SiO2 ratio increases, the luminescence intensity of the Eu3+ ion also increases but that of the Yb3+ ion decreases. The reason for this is that the Al2O3 added to the glass disrupts the symmetry of the surrounding environment where Eu3+ ions exist. As a result, the likelihood of electric dipole transition for these ions is enhanced. Simultaneously, it disrupts the glass network and increases the distance between rare earth ions, leading to a reduction in the luminescence intensity of Yb3+ ions. In addition, the energy transfer process of Eu3+→Yb3+ has potential application prospects in improving the efficiency of silicon-based solar cells by converting ultraviolet light into infrared light.

Electron paramagnetic resonance and luminescence properties of Eu2+ in oxyfluoride barium borate glasses

The Eu-doped xBaO-(100-x)B2O3 and xBaF2-(100-x)B2O3 glasses were prepared by melting method under a reducing atmosphere, exhibiting broadband luminescence peaks of 4f65 d1→4f7 in the excitation range of 300–400 nm. PL, EPR, and XPS were used to analyze the effects of the Ba2+, F−, and Eu ion content on the Eu2+/Eu3+ ratio and Eu2+ emission wavelength and intensity. An excess of Ba2+ ions with a high optical basicity reduced the Eu2+/Eu3+ ratio and enhanced the ligand field strength surrounding the Eu2+ ions, decreasing the Eu2+ luminescence intensity and red-shifting the luminescence peak. The addition of F− had the effect of diminishing the optical basicity, decreasing the OH groups content and eliminating Eu2+ clusters, which not only mitigated the effects of the Ba2+ ions, but also significantly enhanced the luminescence intensity of Eu2+ ions. An increase in the Eu ion concentration led to a red-shift in the Eu2+ fluorescence, which was attributed to the nephelauxetic effect. Therefore, the luminescence color of these glass samples could be manipulated by adjusting the doping concentrations of Ba2+, F−, and Eu2+.

On the luminescence properties of Eu2+ with multiple-site occupancy in silicate K2MgSi3O8

Charge compensating defects, resulting from heterovalent cation substitution, often play an important role in luminescent properties. In this paper, the luminescence properties of K2MgSi3O8:Eu2+ phosphor were studied by means of XRD, PL and decay analysis. It is found that there was only one K+ site to be substituted by Eu2+ in the K2MgSi3O8 host lattice. However, the existence of multiple Eu2+ sites is observed, which is explained by charge compensating mechanism. Unequal substitution is a meaningful way to discover new luminescent materials.

Luminescent properties of Eu (III) complexes with carboxylate ligands and their light conversion films

This study reports the synthesis and characterization of four europium (III) complexes with different carboxylate ligands, namely 2-pyridine-acrylic acid (H2-PA), 2-pyridine-carboxylic acid (HPic), benzoic acid (HBen), and cinnamic acid (HCin), as well as a binuclear europium-lanthanum complex with HCin as the only ligand. The obtained complexes and the light conversion films prepared from them were extensively characterized by various techniques, including elemental analysis, infrared spectroscopy (IR), X-ray single crystal diffraction, thermogravimetric analysis (TGA), and fluorescence spectroscopy. Efforts were made to systemically investigate the structural, coordination, photophysical, and thermal properties of the luminescent materials, and elucidate the correlations between the ligand triplet energy levels and the luminescent properties of the complexes. The results reveal that the introduction of LaIII cannot only enhance the luminescent intensity of the light conversion agent and corresponding film, but also have obvious effect on enhancing the ultraviolet aging resistance of the light conversion film. Moreover, the proper doping concentration (0.5%) of the EuIII complex La-Eu-Cin in film may better balance the properties and cost.

Synthesis and luminescent properties of Eu(III)/Tb(III) rare earth complex-coated the core-shell structured silica microspheres: Unleashing the potential for white light emission

A rare earth organic complex, SiO2@ATPA-Si-RE (RE = Eu, Tb), exhibiting a core-shell structure, was synthesized using the ligand (HOOC)2C6H3NHCONH(CH2)3Si(OCH2CH3)3(ATPA-Si) to connect the silica microspheres core and coordinate with rare earth ions. The pH value of the reaction was adjusted to produce organic complex shells with thicknesses of 2.0 nm and 5.0 nm, while the SiO2 core measured a diameter of 125 nm. Luminescence spectra indicated that the emission intensity of the SiO2@ATPA-Si-RE (RE = Eu, Tb) core-shell structure was stronger than that of the ATPA-Si-RE organic complex due to a perfect match between the triplet energy level of SiO2@ATPA-Si and the excited energy level of rare earth ions (Eu3+, Tb3+). Remarkably, the core-shell structure with a 2.0 nm shell thickness possessed a greater emission intensity compared to the 5.0 nm shell thickness. Moreover, these findings unveiled the tunability of luminescence color, ranging from green or red to white, by adjusting the doping ratio of Eu3+ and Tb3+ ions and the coating thickness of complexes. Particularly, a warm white light emission, characterized by CIE coordinates (0.389, 0.347), a color rendering index value of 86.7, and a low correlated color temperature value of 3550 K, was achieved using the organic complex with a 2.0 nm thickness coated on SiO2 microspheres with a doping ratio of Eu3+ at 0.7 mmol and Tb3+ at 0.3 mmol. Conversely, the complexes with a 5.0 nm coating thickness and Tb3+ doping ratio of 0.3 mmol yielded a cold white light emission. These findings demonstrate the potential applications in next-generation lighting industry and display systems.

Luminescence properties of Eu2+/3+ co-activated La6Sr4(SiO4)6F2 polychromatic phosphors towards white light-emitting diodes and anti-counterfeiting

To obtain emitting color regulation, series of Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors were synthesized. The crystal structure, morphology, elemental compositions and luminescence performances of the final products were discussed. Excited by 365 nm, all of the studied samples can emit the characteristic emissions of Eu2+ and Eu3+, in which their fluorescence intensities have various responses to doping content. Specially, as the dopant content increases, the emitting color is changed from green to yellow. Moreover, via changing the excitation wavelength, tunable emissions are also realized in the studied samples. On the basis of the temperature dependent emission spectra, it is found that Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors possess good thermal stability. Through selecting the designed phosphors as yellow emitting components, a warm white light-emitting diode (white-LED) was packaged, in which its electroluminescence properties are hardly altered at high injection current. When the working current is 100 mA, the color coordinate, correlated color temperature and color rendering index of the fabricated white-LED are (0.358,0.358), 4580 K and 87.39, respectively. In addition, using the resultant compounds as luminescent labels, different patterns were prepared for the application in information encryption. The results demonstrated that Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors with multicolor emissions and outstanding thermal stability are suitable for white-LED and optical anti-counterfeiting as emitting components.

Site regulation and luminescence properties of Eu3+, Eu2+ in (La, Mg):SrAl12O19 matrix

The partially and equivalent substitution of La + Mg → Sr + Al in SrAl12O19 lattice is an effective strategy to provide trivalent sites, reduce the site occupation splitting of Al and stabilize the entire lattice. When excited by 397 nm, the Eu3+ activated La, Mg:SrAl12O19 (ASL) phosphor shows intense linear emission through the 5D0→7F4 transition at 707 nm when compared with SrAl12O19:Eu3+. Especially, the Eu, Mg co-doped Sr1-xLaxMgxAl12-xO19 with certain amount of x = 1/3 exhibits the significant intense photoluminescence, which was demonstrated through a lattice evolutional model. Eu2+ in the host with 1/3 ratio of (La, Mg) substitution shows broad blue emission and as short fluorescence lifetime as 248 ns. The temperature-depended fluorescence quenching behavior confirms the essence of strong electric-phonon coupling originated from distorted and polarized crystal field around Eu2+/Sr2+ site. Basing on site regulation of SrAl12O19 matrix, our study provides a reference for exploration on efficient rare earth ions activated luminescent laser or scintillation materials.

From Framework to Layers Driven by Pressure - The Monophyllo-Oxonitridophosphate β-MgSrP3 N5 O2 and Comparison to its α-Polymorph.

Oxonitridophosphates exhibit the potential for broad structural diversity, making them promising host-compounds in phosphor-converted light-emitting diode applications. The novel monophyllo-oxonitridophosphate β-MgSrP3 N5 O2 was obtained by using the high-pressure multianvil technique. The crystal structure was solved and refined based on single-crystal X-ray diffraction data and confirmed by powder X-ray diffraction. β-MgSrP3 N5 O2 crystallizes in the orthorhombic space group Cmme (no. 67, a=8.8109(6), b=12.8096(6), c=4.9065(3) Å, Z=4) and has a structure related to that of Ba2 CuSi2 O7 . DFT calculations were performed to investigate the phase transition from α- to β-MgSrP3 N5 O2 and to confirm the latter as the corresponding high-pressure polymorph. Furthermore, the luminescence properties of Eu2+ doped samples of both polymorphs were investigated and discussed, showing blue and cyan emission, respectively (α-MgSrP3 N5 O2 ; λmax =438 nm, fwhm=46 nm/2396 cm-1 ; β-MgSrP3 N5 O2 ; λmax =502 nm, fwhm=42 nm/1670 cm-1 ).

Electric field-driven modulation in structural and luminescent properties of Eu3+-doped (1 − x)(Na0.5Bi0.5)TiO3 − xBaTiO3 relaxor ferroelectrics

We investigated the structural, electrical, and luminescent properties of Eu3+-doped (1 − x)(Na0.5Bi0.5)TiO3 − xBaTiO3 (NBT-BT:Eu) relaxor ferroelectrics for x = 0.00–0.08. The introduction of Eu3+ generated good emission properties in the samples without weakening their piezoelectric properties. Rietveld refinement structural analysis revealed that the structural phase of NBT-BT:Eu was a mixture of rhombohedral and monoclinic phases with a significant x-dependence. We observed that NBT-BT:Eu underwent a structural phase transformation upon the application of an electric field. Interestingly, the structural changes caused by poling led to a reduction in the emission of Eu3+. The poling-driven emission quenching behavior resulted from the increase in the local structural symmetry around Eu3+ in the poled samples. We also identified light-induced modulation in the emission of our samples, probably attributed to the photochromic behavior. The multifunctionality of NBT-BT:Eu paves the way for the development of a new type of optoelectronic material.

Synthesis and luminescence properties of Eu3+, Dy3+ co-doped Ca3Bi(PO4)3 single-phase phosphor

Synthesis and luminescence properties of Eu3+, Dy3+ co-doped Ca3Bi(PO4)3 single-phase phosphor

Effects of structural phase changes on the luminescence of Eu-doped (1-x)BaTiO3-xCaZrO3

We investigated the structural and luminescent properties of Eu3+-doped (1-x)BaTiO3-xCaZrO3 (BCTZ:Eu). The changes in the structural symmetry of BCTZ:Eu with CaZrO3 substitution and Eu3+ doping was determined using Rietveld refinement of the X-ray diffraction patterns. Under ultraviolet photoexcitation, the specimens exhibited typical red-orange emission peaks resulting from the f–f transitions from Eu3+ ions. The intensities and asymmetry ratios of the emission intensities, as well as Stark splitting of the emission bands from Eu3+ were found to be strongly dependent on the structural phase transformation of BCTZ from tetragonal to rhombohedral. These findings suggest that BCTZ:Eu possesses a great potential for multifunctional devices that have both ferroelectric and luminous properties.

Synthesis, crystal structure and luminescent properties of Eu3+-activated halotungstates applied in W-LEDs

The self-activated and Eu3+ ions activated halotungstates Ca3WO5Cl2 phosphors have been prepared by the facile solid-state reaction. The crystal structure, photoluminescence excitation (PLE) and emission (PL) spectra, temperature-dependent PLE, and decay curves were investigated. When excited by ultraviolet (UV) light, the pure Ca3WO5Cl2 shows blue emission, which can be ascribed to the typical self-activated emission of charge transfer band (CTB) transitions in [WO5Cl]5- groups. As the temperature increases from 10 to 480 K, the PL intensity decreases, and the emission band appears blue shift. The concentration dependent PL spectra of Ca3WO5Cl2:Eu3+ show several characteristic emission peaks of Eu3+ ions in the red emission region around 615 nm together with the host emission band in the blue emission region at around 450 nm. Accordingly, the broadband originates from the CT behavior in [WO5Cl]5- group, while the sharp lines originate from the 5D0-7F2 transitions in Eu3+ ions. The energy transfer process between Eu3+ and WO5Cl was discussed. All results indicate the possibility for UV to blue LED applications with multi-color emissions in a single stable host.