Optical study of GeO2–PbO–PbF2 oxyfluoride glass singly doped with Pr3+, Nd3+, Sm3+ and Eu3+ (original) (raw)
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Pr3+ and Tm3+ containing transparent glass ceramics in the GeO2–PbO–PbF2–LnF3 system
Journal of Alloys and Compounds, 2004
Oxyfluoride glasses with composition 50GeO 2-(50 − x)PbO-xPbF 2 (x ≤ 15 mol%) containing praseodymium or thulium were melted from commercial raw materials in normal atmosphere. Based on the results of differential thermal analysis (DTA), glass transition temperatures and oxide glass crystallisation temperatures have been derived. Then the glass samples were thermally treated in order to achieve controlled precipitation of PbF 2. Process of formation of glass ceramics has been monitored with the aid of the DTA and X-ray measurements. The control acoustic emission (AE) measurements confirm the DTA results. It has been found that after heat treatment the crystallisation temperatures of investigated materials have been changed due to the PbF 2 content and kind of doped ions. The influence of the kind of doped ions on the glass stability was observed. The effect of thermal treatment on the absorption spectra and kinetics of the fluorescent levels of Pr 3+ and Tm 3+ was studied. In the case of Tm 3+ doped systems it was found that this effect on the relaxation of the 1 G 4 level was weak, whereas the decay of the 3 H 4 level was slower by a factor of 3 roughly with respect to that recorded with as-melted glass. Relaxation rates of the 3 P 0 and 1 D 2 levels of Pr 3+ showed marked dependence on both the PbF 2 and Pr 3+ content in as-melted glass and in glass ceramics.
Journal of Non-Crystalline Solids, 2017
The GeO 2-PbO-Bi 2 O 3-SrF 2 (GePbBiSr) glass systems doped with Eu 3+ , Tb 3+ , Tm 3+ and triply-doped with Eu 3+ / Tb 3+ /Tm 3+ ions were successfully synthesized. Their structural and luminescent properties have been investigated with various techniques. Obtained results indicate that these glass systems are suitable materials for the RE 3+ ions hosts. RE 3+ ions can be excited by single UV light wavelength (355/378/395 nm) and simultaneously emit red, green and blue light originating from Eu 3+ , Tb 3+ and Tm 3+ transitions. Emission color changes from bluish-purple for 355 nm excitation to white when irradiated with 378 nm and 395 nm. The GePbBiSr glass triply-doped by Eu 3+ /Tb 3+ /Tm 3+ ions could be a potential candidate for white LED applications.
Optica …, 2008
Oxyfluoride lead borate glasses singly doped with Nd 3+ and Er 3+ ions have been studied before and after thermal treatment. The orthorhombic PbF 2 crystallites are formed during thermal treatment, which was evidenced by X-ray diffraction analysis. Near-infrared luminescence spectra at 1.06 μm and 1.53 μm have been registered for samples before and after annealing, which correspond to the main 4 F 3/2-4 I 11/2 and 4 I 13/2-4 I 15/2 laser transitions of Nd 3+ and Er 3+ ions, respectively. Luminescence decays from 4 F 3/2 state of Nd 3+ and 4 I 13/2 state of Er 3+ have been analyzed in detail. Contrary to Nd-doped samples, the luminescence lines obtained for Er-doped transparent oxyfluoride glass-ceramics are more intense and narrowed, whereas the luminescence decays from 4 I 13/2 state of Er 3+ are slightly longer in comparison to precursor glasses.
Materials Chemistry and Physics, 2014
Erbium-doped lead-free germanate glasses modified by BaF 2 were prepared. The bonding parameter is reduced with increasing BaF 2 content. The 4 I 15/2 À 2 H 11/2 hypersensitive transition is blue shifted with increasing BaF 2 content. Luminescence spectra due to main 4 I 13/2 À 4 I 15/2 laser transition of Er 3þ were detected. Long-lived NIR emission of Er 3þ is observed for glass samples with low BaF 2 content. a b s t r a c t Spectroscopic properties of Er 3þ ions in lead-free oxyfluoride germanate glasses were studied. The absorption and luminescence spectra of Er 3þ ions were examined for glass samples with low and high BaF 2 content. From absorption spectra the bonding parameter was calculated and its value is reduced with increasing BaF 2 content. The maximum of absorption peak due to 4 I 15/2 À 2 H 11/2 hypersensitive transition is shifted to shorter wavelengths (blue shift) with increasing BaF 2 content. Luminescence spectra and their decays corresponding to main 4 I 13/2 À 4 I 15/2 laser transition of Er 3þ are also presented and discussed. Quite long-lived near-infrared luminescence of Er 3þ is observed for lead-free glass samples with low BaF 2 concentration.
Rare-earth doped oxyfluoride glass-ceramics and fluoride ceramics: Synthesis and optical properties
Optical Materials, 2007
Ultra-transparent glass-ceramics are synthesized in the GeO 2 -PbO-PbF 2 system by rare-earth heterogeneous nucleation of PbF 2 . The influence of YbF 3 on the nucleation process is studied through differential thermal analysis (DTA) and the morphology is observed by transmission electron microscopy (TEM). The optical properties of the glass-ceramics are compared to those of the starting glass as well as to those of a PbF 2 single crystal. Thanks to the RE segregation inside the PbF 2 crystallites, the optical characteristics of the glassceramics are found to be equivalent to those of the single crystal.
Materials
The effect of BaF2, MgF2, and AlF3 on the structural and luminescent properties of gallo-germanate glass (BGG) doped with erbium ions was investigated. A detailed analysis of infrared and Raman spectra shows that the local environment of erbium ions in the glass was influenced mainly by [GeO]4 and [GeO]6 units. Moreover, the highest number of non-bridging oxygens was found in the network of the BGG glass modified by MgF2. The 27Al MAS NMR spectrum of BGG glass with AlF3 suggests the presence of aluminum in tetra-, penta-, and octahedral coordination geometry. Therefore, the probability of the 4I13/2→4I15/2 transition of Er3+ ions increases in the BGG + MgF2 glass system. On the other hand, the luminescence spectra showed that the fluoride modifiers lead to an enhancement in the emission of each analyzed transition when different excitation sources are employed (808 nm and 980 nm). The analysis of energy transfer mechanisms shows that the fluoride compounds promote the emission inten...
Spectroscopic properties of lead fluoroborate and heavy metal oxide glasses doped with Yb< sup> 3+
2002
Energy transfer at 1500 nm in lead fluoroborate glasses (PbO-PbF 2-B 2 O 3) codoped with Er 3ϩ and Yb 3ϩ is studied for the first time to the authors' knowledge. A sample codoped with 1 mol. % of Yb 2 O 3 and 0.01 mol. % of Er 2 O 3 has a measured fluorescence lifetime of (1.30 Ϯ 0.07) ms and an energy transfer efficiency of 80%. Also, a large emission band, of 72.4 nm has a measured peak emission cross section of (0.73 Ϯ 0.06) ϫ 10 Ϫ20 cm 2. The calculated Judd-Ofelt parameters are ⍀ 2 ϭ (3.51 Ϯ 0.14) ϫ 10 Ϫ20 cm 2 , ⍀ 4 ϭ (1.09 Ϯ 0.07) ϫ 10 Ϫ20 cm 2 , and ⍀ 6 ϭ (0.94 Ϯ 0.07) ϫ 10 Ϫ20 cm 2. The temporal evolution of the Yb 3ϩ fluorescence is fitted by use of the Yokota-Tanimoto expression to yield the Yb 3ϩ diffusion constant ͓(1.6 Ϯ 0.2) ϫ 10 Ϫ10 cm 2 s Ϫ1 ͔ and the critical radius of Yb 3ϩ /Er 3ϩ (18 Ϯ 1) ϫ 10 Ϫ8 cm. Results with the singly doped samples produced are presented to clarify the energy transfer process.
Structural and luminescence behavior of lead fluoroborate glasses containing Eu3+ ions
Physica B: Condensed Matter, 2013
Structural and luminescence behavior of lead fluoroborate glasses prepared with the chemical composition (50 À x)B 2 O 3 þ 20PbO þ20PbF 2 þ10ZnOþ xEu 2 O 3 (where x ¼ 0.05, 0.1, 0.5, 1, 2 and 3 in wt%) have been studied by varying the trivalent europium ion content. Structural behavior of the prepared glasses has been explored through XRD, FTIR and Raman spectral analysis. Optical characterization has been made using UV-vis-NIR absorption, excitation, luminescence and decay curves of the present glasses. Through the absorption spectra, bonding parameters (b and d) have been determined and the positive value of d indicates the covalent nature. The band gap values are found to decrease with increasing Eu 3 þ ion concentration whereas Urbach's energy values are found to increase. The PSB associated with the 7 F 0 -5 D 2 excitation transition is used to determine the electron-phonon coupling constant and the local structure of the Eu 3 þ ions with its surrounding ligands. The luminescence intensity ratio of the 5 D 0 -7 F 2 to 5 D 0 -7 F 1 transition has been calculated to estimate the local site symmetry around the Eu 3 þ ions. Judd-Ofelt (J-O) intensity parameters O l (l¼ 2,4,6) were obtained from the emission spectra and the same is used to estimate the transition probability (A), stimulated emission cross-section ðs E P Þ and branching ratios (b R ) for the excited levels of the Eu 3 þ ions.
Thermal and optical investigation of EuF3-doped lead fluorogermanate glasses
Journal of Non-Crystalline Solids, 2010
Europium-doped lead germanate and lead fluorogermanate glasses are studied by using differential thermal analysis, X-ray diffraction, photoluminescence and fluorescence lifetimes measurements of the 5 D j , j = 0, 1, 2 levels. PbF 2 addition increases the thermal stability of the lead germanate glass, while Eu 3+ ions promote the crystallization of b-PbF 2 :Eu 3+ nano-crystals embedded in a glassy matrix. In the lead fluorogermanate glasses, Eu 3+ ions exhibit a strong affinity for F À ions although oxygen ions are much more numerous. It appears that luminescence concentration quenching is not important, while cross relaxation is very efficient in the glasses. The results allow to propose for these glasses a molecular model in which small fluorine rich island, incorporating the Eu 3+ ions in low symmetry sites, are separated from each other by chains of germanate (GeO 4) 4À ions linked together.