[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 article reports on the newly developed heavy metal based multicomponent ZrF₄-BaF₂-LaF₃-YF₃-AlF₃-NaF optical glass systems, which are abbreviated as ZBLYAN glasses for easy reference. These host glass matrices have been doped with rare earth ions such as Pr³⁺ or Dy³⁺ or Tm³⁺ to understand their upconverted emission phenomenon and normal emission as well through a systematic approach. NIR up conversion emissions into visible colours have been reported from these rare earth ions doped optical fibre core based standard glass compositions. The possible mechanisms involved in such upconversion emission processes have been explained more clearly in terms of energy levels schemes. (author)

[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] The validity of Judd-Ofelt theory has been established, as the experimental spectral intensities for Ho(III), Eu(III) and Tb(III) ions in SeOCl₂ + SnCl₄ laser liquid are found to be strongly correlated with the theoretical estimates. Judd-Ofelt intensity (T₂, T₄, T₆) parameters have been computed by employing a least-squares fit method. From the magnitudes of the bonding parameters for the ions studied, it has been suggested that the bonding in the complexes is covalent in nature. (Auth.)

[en] This paper reports the preparation and spectral analysis of two series of Pr³⁺ -doped glasses of the compositions: fluoroborate glasses: B₂O₃-Na₂O-RF (=LiF and NaF) borotellurite glasses: B₂O₃-BaO-TeO₂-RF (=Li, NaF and KF). The computed parametrization of both the physical and the non-linear spectra demonstrates the effects of alkali cations (Li, Na and K) in the glasses studied. (author)

[en] The present paper brings out the results concerning the preparation and optical properties of Sm³⁺ and Dy³⁺ each ion separately in four different concentrations (0.1, 0.5, 1.0 and 1.5 mol%) and also together doped (1 mol% Dy³⁺+x mol% Sm³⁺): Li₂O–LiF–B₂O₃–CdO (where x=0.1, 0.5, 1.0 and 1.5 mol%) glasses by a melt quenching method. Sm³⁺ doped base glasses have displayed an intense orange emission at 602 nm (⁴G_5/2→⁶H_7/2) with an excitation at 403 nm and Dy³⁺ doped glasses have shown two emissions located at 486 nm (⁴F_9/2→⁶H_15/2; blue) and 577 nm (⁴F_9/2→⁶H_13/2; yellow) with λ_exci=387 nm. The co-doped (Dy³⁺+Sm³⁺) lithium fluoro-boro cadmium glasses have been excited with an excitation at 387 nm of Dy³⁺ which has resulted in with a significant reduction in Dy³⁺ emission, at the same time there exists an increase in the reddish-orange emission of Sm³⁺ due to an energy transfer from Dy³⁺ to Sm³⁺. The non-radiative energy transfer from Dy³⁺ to Sm³⁺ is governed by dipole–quadrupole interactions as is explained in terms of their emission spectra, donor lifetime, energy level diagram and energy transfer characteristic factors. -- Highlights: • In co-doped (Dy³⁺+Sm³⁺): LFBCd glass, reddish-orange emission due to Sm³⁺ (⁴F_9/2→⁶H_J) has been enhanced due to an energy transfer from Dy³⁺ ions in the glass. • This has been evidenced from a lowering trend in the emission transition lifetimes of donor (Dy³⁺) ions with increasing acceptor (Sm³⁺) concentration. • Energy transfer mechanism involved in Dy³⁺→Sm³⁺ has been explained in terms of I–H luminescence decay curve analysis

[en] The values of Slater-Condon (F₂, F₄, F₆), Spin-Orbit (Epsilon sub(4f)) Racah (E¹, E², E³) have been evaluated for Nd³⁺ ion in Nd(C₂H₃O₂)₃H₂O, Mg(C₂H₃O₂)₂, Ca(C₂H₃O₂)₂ and Cd(C₂H₃O₂)₂. The bonding nature of these Nd³⁺ complexes has been suggested as covalent from the magnitude of their bonding parameter (delta). By employing Judd-Ofelt theory the observed spectral intensities have been correlated with the theoretical values. The calculated values of the electric (Ssub(ed)), magnetic (Ssub(md)) dipole line strengths, total transition probabilities (A) and predicted total oscillator strengths (f) have also been reported. (author)

[en] The values of Slater-Condon(F₂, F₄, F₆), spin-orbit(xisub(4f)) and configurational interaction (α,β) parameters have been evaluted for Pr³⁺ in Pr₂(SO₄)₃, MgSO₄, ZnSO₄, CdSO₄ and (NH₄)₂SO₄ complexes. The bonding nature of these Pr³⁺ complexes has been suggested as ionic from the magnitude of their bonding parameter (delta). Theoretical evaluation of predicted radiative lifetimes (Tsub(R)) of the electronic excited states ³P₁, ³P₀ and ¹D₂ of Pr³⁺ in five different hosts has been carried out. (author)

[en] Sm³⁺ or Dy³⁺:LiYNbO₃ ceramic powders have been synthesized by a solid-state reaction method to study their photoluminescence properties in order to evaluate their emission performance. Upon exposure to the UV lamp, these luminescent ceramic powders have displayed bright reddish-orange (⁴G_5/2→⁶H_7/2) (Sm³⁺) and yellow (⁴F_9/2→⁶H_13/2) (Dy³⁺) color emissions respectively. (author)