Concentration distribution of Yb2+ and Yb3+ ions in YbF3:CaF2 crystals (original) (raw)
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Calcium fluoride crystals doped with YbF 3 and PbF 2 -, NaF-and LiF-codoped were grown using the vertical Bridgman method. Transparent, high quality, with various high Yb 2+ contents in the as-grown crystals has been obtained using a special procedure. The optical absorption spectra reveal the characteristic ultraviolet (UV) absorption bands of the divalent Yb ions. Influence of the codoping with Pb 2+ , Li + and Na + ions on the absorption spectra and on the Yb 2+ ions content has been studied. High-intensity emission bands in the near-UV spectral region, not reported before, have been observed for excitation by 230 nm. A comparison of our results with those obtained by other authors is also given. r
Optical spectroscopy of Yb2+ ions in YbF3-doped CaF2 crystals
Journal of Crystal Growth, 2008
Transparent colorless Ca 1Àx Yb x F 2+x (x ¼ 0.0007-0.016) crystals were grown using the vertical Bridgman technique. In order to obtain efficient Yb 3+ -Yb 2+ conversion in the as-grown crystals, a special procedure has been developed. Room temperature optical absorption spectra reveal the characteristic UV absorption bands of the Yb 2+ ions in the as-grown crystals, with intensities more than 10 times higher than those reported by other authors using various conversion procedures. The influence of YbF 3 content and of codoping with Pb 2+ ions on the absorption and emission spectra has been studied. Room temperature emission bands in the near UV (not reported before) and in the visible spectral domain have been observed. The emission intensity depends on the dopant concentration. A comparison of our results with those obtained by other authors is also given. r
Influence of Various Impurities on the Optical Properties of YbF3-Doped CaF2 Crystals
Acta Physica Polonica A, 2007
Calcium fluoride crystals doped with YbF3 and co-doped with LiF and NaF were grown using the vertical Bridgman method. Several of rare-earth ions (such as Eu, Sm, Ho, Tm, and Yb) can be stabilized in the divalent state in the CaF2. The change of valence was attained by various methods. The optical absorption spectra reveal the characteristic absorption bands of the Yb 3+ and Yb 2+ ions. This means that the developed crystal growth process achieves a good Yb 3+ to Yb 2+ conversion in the as-grown crystals. The influence of other impurities, such as Na + or Li + , on the absorption and emission spectrum of YbF 3 -doped CaF 2 was studied. The Li + and Na + ions drastically decrease the absorption coefficient of the Yb 2+ ions in the UV band and the emission intensity by excitation in 230 nm.
Influence of some impurities on the emission properties of CaF2:YbF3 crystals
2015
Various concentrations of YbF3-doped and NaF or PbF2 co-doped CaF2 crystals were grown using the conventional Bridgman method. Transparent colorless crystals were obtained in graphite crucible in vacuum using a shaped graphite furnace. The crystals have been cooled to room temperature using an established procedure. Room temperature absorption spectra have been obtained using a Shimadzu 1650PC spectrophotometer. Photoluminescent properties in IR spectral range were analyzed using a spectrofluorimeter Horiba Fluorolog 3. An IR laser diode at 932 nm was also used an directly injected in the equipment. The emission spectra are influenced by the concentration of co-dopant added to the melt, and the excitation wavelength. The high emission peak at 979 nm overlaps with the absorption peak. The highest intensity in the IR emission (around 1029 nm) is obtained for CaF2:0.72 mol% YbF3 crystal by excitation at 932 nm (diode lamp).
Spectra and energy levels of Yb3+ ions in CaF2 transparent ceramics
Journal of Alloys and Compounds, 2014
Fluoride CaF 2 :Yb 3+ transparent ceramics for high power lasers are obtained by vacuum sintering and hot pressing of nanoparticles synthesized through a soft chemistry route. Comparative investigation of the luminescent properties of CaF 2 :Yb 3+ ceramics with the properties of single crystals counterpart is performed. A detailed spectroscopic analysis of the crystal-field splitting of the energy levels of Yb 3+ in CaF 2 ceramics is reported based on assignments made to the absorption and selective emission spectra observed between 905 nm and 1100 nm obtained at 20 K. The experimental Stark energy levels of the two Yb 3+ manifolds are established for all the present site symmetries in the CaF 2 ceramics host. Furthermore, a crystal field investigation of Yb 3+ doped CaF 2 transparent ceramics is presented. Very satisfactory agreement was obtained between calculated and experimental Stark energy levels of Yb 3+ ion corresponding to isolated and complex sites.
Applied Physics B, 2013
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Optical study of Yb 3+ /Yb 2+ conversion in CaF 2 crystals
Journal of Physics: Condensed Matter, 2005
Yb 3+ ions with various site symmetries have been observed in the absorption and emission spectra of Yb 3+ :CaF 2 crystals, both γ -irradiated and annealed in hydrogen. The absorption intensity value is found to be much higher for the γ -irradiated crystal and strongly dependent on the gamma dose. The UV absorption spectra of γ -irradiated and H 2 -annealed CaF 2 :5 at.% Yb 3+ crystals are quite similar. Yb 2+ absorption bands are observed at 360, 315, 271, 260, 227 and 214 nm, which are called A, B, C, D, F and G bands, respectively. For γ -irradiated CaF 2 :30 at.% Yb 3+ , an additional band at 234 nm can be seen. It is suggested that only a negligible amount of Yb 3+ ions are converted into Yb 2+ under the γ -irradiation. The presence of Yb 2+ is confirmed by the 565 and 540 nm luminescence under 357 nm excitation. It is also suggested that the excitation in the A, C, D and F absorption bands of Yb 2+ gives rise to photoionization of Yb 2+ ions and electrons in the conduction band to form the excited Yb 3+ ions which emit IR Yb 3+ luminescence.
Influence of Yb3+ ions on the optical properties of double-doped Er,Yb : CaF2 crystals
Physica Scripta, 2011
analysis is used to estimate the magnitude of the forced (4f-4f) transition probabilities of Er 3+ ions in double-doped (Er,Yb) : CaF 2 crystals. The studied crystals were grown in our crystal research laboratory using the vertical Bridgman method. The J-O intensity parameters 2 , 4 and 6 were calculated from the optical absorption spectra. These parameters were then used to evaluate the spontaneous transition probability, the line strength, the branching ratio and the radiative lifetime. The obtained radiative decay rates were compared with the luminescence spectra. Phys. Scr. 83 (2011) 025604 G Buse et al of f-f intermanifold J -J transitions between excited states J and the lower-lying terminal manifolds J , can be calculated using the expression 64π 2 e 2 3h(2J + 1)λ 3 mean n(n 2 + 2) 2 9 S ed J J + n 2 S md J J , where S ed J J and S md J J are defined by equations and ,
Synthesis and down-conversion luminescence investigation of CaF2:Yb:Ce powders for photonics
Journal of Fluorine Chemistry, 2019
Highlights The single-phase solid solutions of calcium fluoride doped with ytterbium and cerium trivalent ions have been synthesized by the precipitation from aqueous solutions technique. Analysis of the luminescence kinetics has shown significant energy transfer from Ce 3+ to Yb 3+ under excitation upon 266 nm. The maximum down-conversion Yb 3+ luminescence quantum yield (5.6%) upon 266 nm pumping was recorded for the CaF2:Ce(0.1 mol%):Yb (10 mol%) solid solution.