Papers by Keyword: Europium

Abstract: Europium doped lithium barium borate glasses were fabricated by conventional melt-quench method and were analyzed their physical, optical and luminescence properties through absorption, excitation, emission and decay analysis at room temperature. The experimental data revealed that the five discrete absorption bands peaking at 393, 464, 532, 2032 and 2212 nm due to the transitions from ⁷F₀ ground state level to various excited states of Eu³⁺ ions. The luminescence of Eu³⁺ in visible bands were observed under 394 nm pumping.

Abstract: Eu³⁺-doped lithium barium borate glasses of the composition 50Li₂O : 20BaO : (30-x)B₂O₃ : xEu₂O₃, where x = 0.00, 0.10, 0.30, 0.50, and 1.00 mol%. The glasses were fabricated by normal melt quenching technique at 1,000^°C and their properties were investigated. The emission spectra of Eu³⁺-doped glasses were recorded in wavelength range of 550-770 nm with 394 nm excitation. All the spectra exhibited 5 emission bands corresponding to the ⁵D₀→⁷F₀, ⁵D₀→⁷F₁, ⁵D₀→⁷F_2, ⁵D₀→⁷F₃ and ⁵D₀→⁷F₄ transition, respectively. The peak intensities increase with the increase of concentration from 0.10 to 1.0 mol%

Abstract: The photoluminescence properties of lithium yttrium borate glasses doped with Eu³⁺ (LiYB:Eu³⁺) were studied in this work. Glass samples were prepared by melt-quenching technique with variation of Eu₂O₃ doped concentration between 0.00 – 6.00 mol%. The absorption spectra show that LiYB:Eu³⁺ glasses absorbed photon in visible light (VIS) and near-infrared (NIR) region. Photon absorption at 394 nm can excite glass to emit the number of photons in VIS region such as 591, 613, 653 and 701 nm. The strongest emission belong to the light with 613 nm wavelength. The optimum concentration of Eu₂O₃ for LiYB glass is 4.00 mol%. Judd-Oflet (J-O) analysis was used to study on 4.00 mol% doped glass, which shows the interesting potential for using this glass as gain medium in 701 nm emitting laser.

Abstract: Lanthanum calcium phosphate glasses doped with Eu³⁺ ions in compositions 20La₂O₃:10CaO:(70-x)P₂O₅:xEu₂O₃ (where x = 0.05, 0.10, 0.50 and 1.50 mol%) were prepared by melt-quenching technique. The density and molar volume measurements were carried out at room temperature. The absorption spectra were investigated in the UV-Vis-NIR region from 200 to 2500 nm. The emission spectra of Eu³⁺-doped glasses centered at 590 nm (⁵D₀→⁷F₁), 612 nm (⁵D₀→⁷F₂), 652 nm (⁵D₀→⁷F₃) and 699 nm (⁵D₀→⁷F₄) have been observed with 393 nm excitation wavelength.

Abstract: Alkaline earth metal aluminates activated by rare-earth ions (REⁿ⁺) possess intensive luminescence upon UV excitation. The paper studies phase formation of calcium aluminate prepared by the sol-gel method. The stages of the end products’ formation using methods of the thermal and the infrared spectrometric analysis and X-ray diffraction are proposed. Dependence of phase composition, the surface morphology and luminescence properties on the annealing temperature of the precursor is investigated.

Abstract: Hydroxyapatite (HA) doped with europium (HAEu) offers the advantage of making the hydroxyapatite a fluorescent biomarker, allowing their imaging through emission in vivo and in vitro tests. Several authors had been based their studies about europium site occupation (CaI and CaII) in hydroxyapatite by the lanthanide ion luminescence, verifying the influence of the method of synthesis and concentration of the dopant ion. In this study HA nanoparticles doped with 1.4 mol% of trivalent europium were synthesized by co-precipitation method and thermal treated at different temperatures (600°C and 1200°C). A careful evaluation of the influence of the excitation wavelength of europium luminescence in the HAEu was performed and it has been verified that both the characteristics transitions of europium, at CaI and CaII sites, and the luminescent intensity are dependent on the excitation wavelength. The non-observance of this fact can lead to erroneous conclusions about the site occupation of europium in hydroxyapatites.

Abstract: Triboluminescence properties of chemical compound based on Terbium (III) - Tb (АА)₃Phen - are studied by means of new experimental technique developed in this work. It is found that the synthesized complex manifests 20% higher integral intensity of triboluminescence in comparison with that for compound based on Europium (III) –ТЕА[Eu (DBM)₄] which is one of best triboluminophores in the visible spectral range.

Abstract: The CaCO₃ and CaCO₃:Eu³⁺ phosphors have been synthesized by solid state reaction at room temperature without further sintering treatment. The morphology, crystalline structure, and fluorescent properties of the samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), spectrofluorometer, respectively. Also, the influences of Eu³⁺-doping concentration on the photoluminescence (PL) properties were investigated in detail. The results indicate that the morphology of as-prepared CaCO₃ particles are irregular cubic in shape and about 200-400nm in size, while the CaCO₃:Eu³⁺ particles are the aggregates of many small nanoparticles with nearly 30nm in size, indicating that Eu³⁺ ions have a great influence on the CaCO₃ particle morphology and size. The lines around 392nm in luminescence excitation spectrum is the most noticeable. Upon excitation at 392nm, the PL emission spectrum is composed of two band and strong peaks at 589nm and at 613nm. The peaks at 589nm is attributed to magnetic dipole transition ⁵D₀–⁷F₁ and with the increase of the Eu³⁺-doped concentration, the intensity decreases gradually; but it shows the opposite trend for the peak at 613nm which is attributed to the hyper sensitively forced electric dipole transition⁵D₀–⁷F₂.