Yb2O3 Concentration Research Articles

(Invited) Solid Oxide Membrane Process for the Reduction of Uranium Oxide Surrogate in Spent Nuclear Fuel

Solid oxide membrane (SOM) electrolysis was employed to reduce ytterbium oxide (Yb2O3) which was identified as a possible surrogate for uranium oxide in spent nuclear fuel treatment. In this research, an yttria-stabilized zirconia (YSZ) tube was used as the SOM membrane in a LiF-YbF3-Yb2O3 salt to reduce ytterbium (Yb) metal on an inert cathode. The melting point of the supporting electrolyte (LiF-YbF3) was analyzed as a function of Yb2O3 concentration. The stability of YSZ tubes at the electrolysis operating temperature in the chosen flux was characterized. Yb metal deposited on the cathode during the SOM electrolysis process was analyzed.

Electrochemical study on preparation of Mg-Li-Yb alloys in LiCl-KCl-KF-MgCl2-Yb2O3 melts

This paper presented a novel study on electrochemical codeposition of Mg-Li-Yb alloys in LiCl-KCl-KF-MgCl2-Yb2O3 melts on molybdenum. The factors of the current efficiency were investigated. Electrolysis temperature had great influence on current efficiency; the highest current efficiency was obtained when electrolysis temperature was about 660 °C. The content of Li in Mg-Li-Yb alloys increased with the high current densities. The optimal electrolytic temperature and cathodic current density were around 660 °C and 9.3 A/cm2, respectively. The chemical content, phases, morphology of the alloys and the distribution of the elements were analyzed by X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry, respectively. The intermetallic of Mg-Yb was mainly distributed in the grain boundary of the alloys, presented as reticulated structures, and refined the grains. The lithium and ytterbium contents in Mg-Li-Yb alloys could be controlled by changing the concentration of MgCl2 and Yb2O3 and the electrolysis conditions.

Fluorescence and Spectroscopic Properties of Yb3+-Doped Phosphate Glasses

Abstract The concentration dependent Yb 3+ : phosphate (P2O5 + K2O + MgO + Al2O3 + Yb2O3) glasses have been prepared and characterized their fluorescence and laser properties. The stimulated emission cross-section and laser performance parameters were determined from the measured absorption spectra using the method of reciprocity. The refractive index, absorption and emission cross-sections and fluorescence lifetimes varied with Yb3+ ion concentration. The higher emission cross-section was found to be 1.01 × 10-20 cm2 at the extraction wavelength of 1005 nm. The fluorescence lifetime of 2F5/2 level decreases from 1.04 ms to 0.28 ms with increase of Yb2O3 concentration from 0.05 to 6.0 mol %. The gain cross-section spectra can be obtained from the measured absorption and emission cross-sections with different population levels. The values of emission cross-section, fluorescence lifetime, minimum pulse duration, pump power, extraction efficiency and gain coefficients suggest that these glasses can be used as a laser gain media for the generation of ultrashort pulse and high power laser applications.

Optimization of Bi2O3–B2O3-based glass phosphor co-doped with Yb3+ and Nd3+ for optical coherence tomography light source

We have optimized Yb2O3 concentration, Nd2O3 concentration, and thickness of a Yb3+, Nd3+ co-doped Bi2O3–B2O3-based glass phosphor to achieve a higher output power with a Gaussian-like shaped luminescence for an optical coherence tomography (OCT) light source. A simple model that includes absorption of excitation light, absorption of luminescent light, and luminescence efficiency was used for estimation of the output power. We have estimated from the model that the highest output power was achieved at Yb2O3 concentration of 3%, Nd2O3 concentration of 0.5%, and the thickness of 1.8 mm. This estimation showed a good agreement with the experimental results. For the optimized glass phosphor, we have observed Gaussian-like shaped luminescence, which is important for the OCT light source.

Temperature influence on the photodarkening kinetics in Yb-doped silica fibers

We report on the characterization of photodarkening (PD) kinetics of Yb-doped fiber samples in a wide temperature range from 77 to 773 K and with respect to different Yb2O3 concentrations from 0.09 up to 0.68 mol%. The thermal dependency of important PD parameters is presented for a uniform Yb inversion of about 0.46. We have found out that PD kinetics is affected remarkably by temperature during pumping and that PD saturation is an equilibrium of optical and thermal processes, achieved after passing a loss maximum. The saturated loss for time tending to infinity obviously depends on the fiber temperature.

Broadband downconversion from oxygen-deficient centers to Yb^3+ in germanate glasses

We report broadband downconversion from ultraviolet to near-infrared in Yb3+-doped oxygen-deficient SrO-Al2O3-GeO2 glasses. Oxygen-deficient centers are introduced in germanate glasses by adding metal Al instead of corresponding oxide (Al2O3). Tunable luminescence related to these defects is observed. Conversion of broadband ultraviolet light to blue-green tunable luminescence and to near-infrared emission is detected in glasses. The energy transfer efficiency increases with increasing Yb2O3 concentration. The dependence of energy transfer efficiency on wavelength is also discussed.

Conversion of near-ultraviolet radiation into visible and infrared emissions through energy transfer in Yb2O3 doped SrO–TiO2–SiO2 glasses

We demonstrated the conversion of near-ultraviolet radiation of 250–350 nm into visible emission of 450–600 nm and near-infrared emission of 970–1100 nm in the Yb2O3 doped transparent 40SrO-20TiO2-40SiO2 glasses. The observed broad visible emission band centered at 510 nm is associated with silicon-oxygen-related defects in the glassy matrix, and the near-infrared emission originated from the Yb3+ F25/2→F27/2 transition is due to the energy transfer from silicon-oxygen-related defects to Yb3+. The energy transfer process was studied by both the steady state spectra and the time-resolved spectra of Yb3+ at 15 K. The temperature dependent energy transfer rate was calculated. The Yb2O3 concentration dependent energy transfer efficiency has also been evaluated, and the maximum value is 56% for 12 mol % Yb2O3 doped glass.

Energy transfer and enhanced broadband near-infrared luminescence in Yb–Bi codoped phosphate glasses

In this article, we report on enhanced broadband near-infrared emission in Yb–Bi codoped phosphate glasses. The emission intensity of Yb–Bi codoped glass was ˜32 times larger than that of Bi-doped glass when excited with 980-nm laser diode. The highest 1/e fluorescent lifetime of Yb–Bi codoped glass reached 1650 μs. The dependence of emission intensity and fluorescent lifetime on Yb2O3 concentration was investigated. The enhancement of the near-infrared emission is due to energy transfer from Yb3+ (2F5/2–2F7/2) transition to Bi ions, and the highest energy transfer efficiency reached 50%. Yb–Bi codoped phosphate glass should be a promising candidate for broadband optical amplification.

High-Power $\hbox{Yb}^{{\bm 3}{\bm +}}$-Doped Phosphate Fiber Amplifier

We report on the development of novel high-power light sources utilizing a Yb3+-doped phosphate fiber as the gain element. This host presents several key benefits over silica, particularly much higher Yb2 O3 concentrations (up to 26 wt%), a 50% weaker stimulated Brillouin scattering (SBS) gain cross section, and the absence of observable photodarkening even at high population inversion. These properties result in a greatly increased SBS threshold compared to silica fibers, and therefore, potentially much higher output powers out of either a multimode large mode area or a single-mode fiber, which means in the latter case a higher beam quality. To quantify these predictions, we show through numerical simulations that double-clad phosphate fibers should produce as much as ~ 700 W of single-frequency output power in a step index, single-mode core. As a step in this direction, we report a short phosphate fiber amplifier doped with 12 wt% Yb2 O3 that emits 16 W of single-frequency single-mode output. We also describe a single-mode phosphate fiber laser with a maximum output power of 57 W. The laser slope efficiency is currently limited by the fairly high fiber loss ( ~ 3 dB/m). Measurements indicate that 77% of this loss originates from impurity absorption, and the rest from scattering.

Energy transfer between silicon–oxygen-related defects and Yb3+ in transparent glass ceramics containing Ba2TiSi2O8 nanocrystals

We report on the conversion of near-ultraviolet radiation of 250–350 nm into near-infrared emission of 970–1100 nm in Yb3+-doped transparent glass ceramics containing Ba2TiSi2O8 nanocrystals due to the energy transfer from the silicon–oxygen-related defects to Yb3+ ions. Efficient Yb3+ emission (F25/2→F27/2) was detected under the excitation of defects absorption at 314 nm. The occurrence of energy transfer is proven by both steady state and time-resolved emission spectra, respectively, at 15 K. The Yb2O3 concentration dependent energy transfer efficiency has also been evaluated, and the maximum value is 65% for 8 mol % Yb2O3 doped glass ceramic. These materials are promising for the enhancement of photovoltaic conversion efficiency of silicon solar cells via spectra modification.

Dramatic change of guiding properties in heavily Yb-doped, soft-glass active fibers caused by optical pumping

The authors report experimentally observed qualitative changes of the waveguiding properties in ytterbium-doped fibers with high concentration of doping when the fibers are optically pumped with light at the 975nm wavelength. They found that when concentration of Yb2O3 in a single-mode fiber exceeds ∼10wt.% and the pump power is gradually increased, the fiber first looses index-induced guidance, and then regains guidance as the population inversion in Yb+3 ions becomes sufficient for gain guiding. The associated variation of the mode-field diameter is a practically important effect that will complicate design and operation of fiber lasers and amplifiers based on highly Yb-doped glass.

Upconversion emissions in Yb3+–Tm3+-doped tellurite glasses excited at 976 nm

Intense Tm3+ blue upconversion emission has been observed in Tm3+-Yb3+ codoped oxyfluoride tellurite glass under excitation with a diode laser at 976 nm. Three emission bands centered at 475, 650 and 796 nm corresponding to the transitions (1)G(4) -> H-3(6), (1)G(4) -> H-3(4) and F-3(4) -> H-3(6), respectively, simultaneously occur. The dependence of upconversion intensities on Tm3+ ions concentration and excitation power are investigated. For fixed Yb2O3 concentrations of 5.0 mol%, the maximum upconversion intensity was obtained with Tm2O3 concentration of about 0.1 mol%. The blue upconversion luminescence lifetimes of the Tm3+ transitions (1)G(4) -> H-3(6) are measured. The results are evaluated by the possible upconversion mechanisms.

Up-conversion luminescence of Er 3+/Yb 3+/Nd 3+-codoped tellurite glasses

Up-conversion luminescence and energy transfer (ET) processes in Nd 3+–Yb 3+–Er 3+ triply doped TeO 2–ZnO–Na 2O glasses have been studied under 800 nm excitation. Intense green up-conversion emissions around 549 nm, which can be attributed to the Er 3+: 4S 3/2→ 4I 15/2 transition, are observed in triply doped samples. In contrast, the green emissions are hardly observed in Er 3+ singly doped and Er 3+–Yb 3+ codoped samples under the same condition. Up-conversion luminescence intensity exhibits dependence of Yb 2O 3-concentration and Nd 2O 3-concentration. Up-conversion mechanism in the triply doped glasses under 800 nm pump is discussed by analyzing the ET among Nd 3+, Yb 3+ and Er 3+. And a possible up-conversion mechanism based on sequential ET from Nd 3+ to Er 3+ through Yb 3+ is proposed for green and red up-conversion emission processes.

Thermoluminescence of ZrO2 doped with Yb2O3 following excitation with x rays

This study examines the thermoluminescence (TL) of ytterbium oxide (Yb2O3)-doped zirconia (ZrO2) in response to ultraviolet (UV) and synchrotron x-ray excitations. Experimental results demonstrate that, as well as a strong TL peak at 105°C and a weak peak at 205°C, another small peak appears at 150°C. The TL peak at 150°C exhibits dopant concentration quenching. The intensity of the two small peaks, particularly that at 150°C, increases rapidly with the energy of the photons. However, increasing the doping concentration of Yb2O3 reduces the intensity of both TL peaks at 105 and 205°C, and reduces the ZrO2 content in the monoclinic phase. This finding indicates that the intensities of both TL peaks at 105 and 205°C are associated with the ZrO2 content in the monoclinic phase. Additionally, the TL glow remains clearly observed from both undoped and doped samples after 48h of storage. Doping ZrO2 with Yb2O3 reduces the rate of fading of TL from the undoped ZrO2 sample. The stable TL peak of the Yb2O3 dopant at 150°C indicates its greater effectiveness than pure ZrO2 in dosimetry. These observations and their implications are discussed.

Blue cooperative emission in Yb3+ - doped GeO2 - PbO glasses

Investigation of the blue cooperative luminescence in a binary composition of GeO2-PbO glasses with different Yb3+ concentrations is reported. High refractive index (1.96) and large transmission window (0.4 up to 5.0 µm) are characteristics of this vitreous system. Luminescence and lifetime measurements in the visible and near infrared regions were performed to investigate the spectroscopic characteristics of the glasses. Visible emission around 507 nm was detected in all samples. The visible emission intensity increases with the Yb2O3 content at least up to 2.0 wt. (%), that represents the maximum Yb2O3 concentration possible for this glass system. The visible lifetimes are about half of their respective near infrared ones, and the blue luminescence comes from a cooperative process. A rate equation was used to describe the behavior of the cooperative emission intensity as a function of Yb2O3 concentration; a good agreement with the calculated and measured cooperative luminescence was achieved.

Optical properties and cooperative luminescence of Yb-doped borate-silicate glasses

Yb-doped borate-silicate glasses with various Yb2O3 concentrations were fabricated by means of high-temperature solid-state reaction. The absorption and the photoluminescence, as well as the Raman spectra, were measured and analyzed. The absorption and emission cross-section around 980nm is calculated based on the absorption measurement. The dependence of radiative lifetime of Yb3+-2F5/2 on Yb2O3 concentration is also presented. The relationship between up-conversion photon and the infrared emission, together with the assistant phonon, is described according to the up-conversion photoluminescence and Raman spectra analysis.

Crystallization Region, Crystal Growth, and Characterization of Rubidium Titanyl Phosphate Codoped with Niobium and Lanthanide Ions

We studied the crystallization region of RbTiOPO4 (RTP) codoped with Nb and Ln (Ln = Er3+ or Yb3+), taking as basis a range of molar ratios of Rb2O−P2O5−TiO2. Significant differences in the critical concentration of Nb2O5 and Ln2O3 when we substituted TiO2 with these oxides where observed. These differences depended on the initial molar ratio of Rb2O−P2O5−TiO2 used in each case. The critical concentrations of the two lanthanides were also different; the critical concentration of Yb2O3 was lower than that of Er2O3 for all compositions. The distribution coefficients and concentration of Ln in the crystals were higher for Yb3+ than for Er3+, comparing similar concentrations in the solution. Single crystals of RTP:(Nb,Er) and RTP:(Nb,Yb) were grown with optical quality, and these were large enough to make spectroscopic characterizations.

Spectroscopic properties and energy transfer in Yb3+/Er3+-doped phosphate glasses

Abstract The phosphate glasses with high Yb3+/Er3+ dopant were prepared. The absorption and fluorescence emission spectra were measured, and the emission cross-section for 4 I 13/2 → 4 I 15/2 transition of Er3+ was calculated on the basis of McCumber theory. The energy transfer (ET) and the effect of changing concentrations of Er3+ and Yb3+ ions on spectroscopic properties were investigated, pumping at 970 nm. The optimizations of Yb2O3 and Er2O3 concentration were found in our glasses. The influence of –OH groups on the ET and the emission at 1.54 μm were also discussed.

Liquid Immiscibility in the Systems Na2O‐Yb2O3‐B2O3‐SiO2 and K2O‐Yb2O3‐B2O3‐SiO2

Limits of miscibility were determined for portions of the systems Na2O‐Yb2O3‐B2O3‐SiO2 and K2O‐Yb2O3‐B2O3‐SiO2 in the range 650° to 800°C, at Yb2O3 concentrations up to 5 mol%, and at a fixed SiO2/B2O3 mole ratio of 2.0. Regions of the phase diagrams at higher Yb2O3 concentrations were not accessible because of interference from crystallization. The miscibility gaps have topographies similar to those found in the alkali‐metallalkaline‐earth borosilicate systems, X2O‐MO‐B2O3‐SiO2.