[en] This paper presents the results concerning the photoluminescence spectra of 53ZrF₄-20BaF₂-2LaF₃-2YF₃-3AlF₃-(20-x)NaF-xEuF₃ multi-component heavy metal fluoride glasses with the Eu³⁺=0.2, 0.4, 0.8, 1.0, 1.2 and 1.4 mol% in order to evaluate the threshold of concentration quenching (C_q=1 mol%) which corresponds to the concentration limit clearly revealing an intense red emission (⁵D₀→⁷F₂ at 614 nm) from such a luminescent glass. A bright red emission was observed by the naked eye from these materials under an UV source. The dopant ion concentration quenching on the emission behaviour has been ascribed to cross-relaxation and dipole-dipole interactions in the glass matrices. Influence of changes in active ions content (N_Eu³⁺x10²² cm^-3) on the values of inter-ionic distance (r_i A) and polaron radius (r_p A) has been verified. The photoluminescence spectra are constituted essentially by six emission transitions of (⁵D₀→⁷F_{J=0,1,2,3,4,5}) between the wavelengths of 575 and 720 nm. We have also investigated the dependence of emission intensities and lifetimes on various pump wavelengths and identified a more suitable excitation line at 394 nm, which belongs to the transition ⁷F₀→⁵L₆ of Eu³⁺ ion

[en] The present investigation aims at elucidating the photoluminescence behaviour of Tb³⁺ doped 53ZrF₄-20BaF₂-2LaF₃-2YF₃-3AlF₃-(20-x)-NaF-xTbF₃ (where x=0.2,0.4,0.6,0.8,1.0,1.5 and 2.0 mol%) optical glasses. We have measured two prominently intense emission blue group bands (⁵D₃→⁷F_j=6,5,4,3 at 382, 415, 436 and 461 nm) and green group bands (⁵D₄→⁷F_j=6,5,4,3 at 488, 544, 584 and 623 nm) with an excitation at λ_exc=229 nm (4f⁸→4f⁷5d¹) from these ZBLYAN glasses. Under a UV source (15 W), more prominent and rich green luminescent colour (544 nm) has been noticed from these terbium glasses. In particular, glass with low Tb³⁺ (0.2 mol%) content has displayed the emission transitions of ⁵D₃→⁷F_j=6,5,4,3 and at still higher concentrations these emission bands have disappeared completely because of resonant energy transfer phenomenon or cross-relaxation process. The mechanism behind such a process has been explained in terms of an energy level diagram. Among the seven-terbium glasses, one glass with 1.0 mol% of Tb³⁺ (as the optimum content) has revealed an intense green emission

[en] This paper describes the development and a detailed analysis carried out on the luminescence characteristics of Pr³⁺ doped ZrF₄-BaF₂-LaF₃-YF₃-AlF₃-NaF glasses. In the present work our objectives are to elucidate the possible mechanisms that are responsible for NIR to red upconversion process and yellow to blue upconversion emission in terms of energy level schemes from the praseodymium containing fibre optical glass composition. We have studied their different physical and optical properties. Besides our investigation on the upconversion emission of these glasses, normal fluorescence studies have also been undertaken in explaining the mechanisms in demonstrating bright red and blue emissions upon excitations at visible and UV wavelengths. Besides these measurements works, a bright blue colour emission was observed under an UV source (202 nm) and upconverted prominent red emissions were observed with a laser diode (LD of 980 nm). Similarly under a yellow light source, a blue colour emission was observed from these praseodymium glasses studied

[en] Approximate KNO scaling is found to hold in a mixed two-component model up to anti pp collider energies. It is shown that fragmentation processes play an increasingly dominant role with higher energies. This should result in the appearance of a ''bump'' which is already apparent at collider energies. A clearer picture is predicted at √s=1 TeV. (orig.)

[en] Thin film of Zn₂SiO₄:Mn²⁺ has been deposited on SiO₂ buffered Si (SiO₂/Si) wafers by the sol-gel process by means of a spin coating. Structural details of these films have been examined with X-ray diffraction (XRD) profiles and found to be rhombohedral structures. AFM images of the films have revealed that the structure has nano-meter size particles of about 130-160 nm in diameter and surface roughness RMS of 15 nm. FTIR profiles of these films have confirmed that OH content decreases with increasing annealing temperature and thereby enhancing the emission intensity. The OH content has disappeared when the films were annealed at 900 deg. C and above. Thin films of Zn₂SiO₄ containing a 5 mol% Mn²⁺ annealed at 1000 deg. C for about 10 min have shown a bright green luminescent color at 525 nm [⁴T₁(⁴G)→⁶A₁(⁶S) transition]. Luminescence spectra beyond 5 mol% of Mn²⁺:Zn₂SiO₄ have shown a decreasing trend in their green emission behavior due to a cross-relaxation process. A double exponential fitting analysis has been employed to obtain the lifetime of this green emission, the average lifetime was found to be 8.233 ms. Such an encouraging luminescence performance from these thin films strengthens our proposal in developing them as flat panel luminescent systems

[en] We report on the development and luminescence performance of a new family of optical glasses containing Eu³⁺(1 mol%) in the chemical composition of 75Bi₂O₃-21B₂O₃-4R₂O (where R = Li, Na and K) that are labelled as Eu³⁺: Glass A, B and C respectively with an extended infrared transmitting wavelength extending up to 8 μm. We have also investigated the different physical and non-linear properties and zero material dispersion wavelength of the reference glasses without the dopant Eu³⁺ and the results are presented. Under an UV source, especially with Li⁺ added, Eu³⁺: glass displayed a bright red emission at 614 nm (⁵D₀→⁷F₂). Among the different excitation bands, ⁷F₀→⁵L₆ (392 nm) is a spin allowed transition which prominently demonstrates stronger emissions of ⁵D₀→⁷F₀ (578 nm); ⁵D₀→⁷F₁ (593 nm); ⁵D₀→⁷F₂ (614 nm); ⁵D₀→⁷F₃ (654 nm); ⁵D₀→⁷F₄ (688 nm); ⁵D₀→⁷F₅ (702 nm); from all three glasses. The emission process has been explained by means of an energy level scheme

[en] Red-light-emitting Y₂O₃:Eu³⁺ thin-film phosphors were synthesized using a sol-gel process. The effect of Mg²⁺ and Al³⁺ co-dopants on the Y₂O₃:Eu³⁺ thin-film phosphor photoluminescence (PL) property was investigated. At a certain concentration, both Mg²⁺ and Al³⁺ co-dopants were found to further enhance the PL emission intensity of Y₂O³:Eu³⁺ thin-film phosphors. The optimum PL emission intensity was observed in Y₂O₃:12%Eu³⁺, 7%Mg²⁺ and Y₂O₃:12%Eu³⁺, 2%Al³⁺ phosphor films. From our results, the enhancement of the emission intensity by the Mg²⁺ and Al³⁺ co-dopants is explained in terms of the creation of defect states near the Y(4d+5s) conduction band, which overlap with the Eu³⁺ charge-transfer state (CTS). The overlapping leads to CTS broadening and consequently induces higher absorption and hence an increase of the emission intensity. From X-ray diffraction results, we have found that there is no additional phase formed in the co-doped phosphor films

[en] In this work, we demonstrate that yttrium 2-methoxyethoxide is a convenient sol-gel precursor to synthesize the Y₂O₃:Eu³⁺ phosphor films. The crystallization of Y₂O₃:Eu³⁺ phosphor films prepared from the yttrium 2-methoxyethoxide occurs at about 550 deg. C. We have also observed that our Y₂O₃:Eu³⁺ phosphor films undergo crystal structure change above annealing temperature of 750 deg. C which is not previously observed in the sol-gel fabrication method. The change of photoluminescent (PL) spectra is related to the evolution of Y₂O₃ crystal structure. It is shown in this investigation that the post-annealing treatment will help to produce phosphor films of improved brightness. The reasons assigned are the effective elimination of OH impurities and the grain growth of phosphor films