Infrared-to-Visible Frequency up-Conversion in Trivalent Erbium Ions Doped Fluoride Glasses (ZnF_2-Al_F3-PbF_2-LiF)

High efficiency frequency up conversion in trivalent erbium ion doped new fluoride glass matrix (ZnF 2 AlF 3 PbF 2 LiF) was investigated. Under 950 nm laser diode excitation, the glasses gave very intense green, weak red and violet emissions. The up conversion mechanism is discussed. In addition, the infrared transmittance spectrum, the Raman spectrum and the lifetime of the trivalent erbium states in the samples were measured. The results illustrate the large potential of these new glasses for photonic applications.

Relationship between Composition, Density and Refractive Index for Heavy Metal Fluoride Glasses

The density and the refractive index for various compositions of heavy metal fluoride (HMF) glasses, used to make low loss optical wave guides, have been measured by standard archimedes method and by using as Pulfrich refractometer respectively. The density as a function of composition is calculated considering the effective volume of the ions contained in the glass to be invariant. The refractive index as a function of composition is also calculated, based on the Lorenz Lorentz equation, by computing the electronic polarizability of HMF glasses. All calculated results are in good agreement with the observed data.

Immobilization of radioactive fluoride waste in aluminophosphate glass:a molecular dynamics simulation

Molecular dynamics(MD) simulations were conducted to investigate the structural and chemical environment of aluminum in aluminophosphate glasses.Such glasses have the potential for application in the disposal of radioactive fluoride waste from molten salt reactors(MSR).Due to the risks of studying these materials and the limitations of realistic research conditions,MD simulations were used as an alternative method to study the vitrification of radioactive fluoride waste.In the past decades,aluminophosphate glasses have been studied and they exhibit certain favorable properties for high-level radioactive waste management.This work focuses on the effects of fluorine addition on structural changes in the glass.We observed that glass with composition P_2O_5–Al_2O_3–Na_2O–CaO exhibited a good performance in immobilizing fluoride at low F concentrations(approximately under25 mol%).Significant changes were observed where PO_3F_2 units replaced PO_3F units in the glass.The fourcoordinated AlO_4 units were increasingly converted into five-coordinated [AlO_xF_y] with the increasing F content.The radionuclide Sr in the simulation had the tendency to form six-coordinated octahedrons in the glass.We conclude that the structural changes resulting from the fluoridewaste added to aluminophosphate glasses does not adversely affect their chemical stability at relatively low F concentrations,i.e.,under 25 mol%.Hence,the use of phosphate glasses is a potential alternative method of fluoride waste disposal.

Properties of phosphate glass waste forms containing fluorides from a molten salt reactor

Radioactive fluoride wastes are generated during the operation of molten salt reactors(MSRs) and reprocessing of their spent fuel.Immobilization of these wastes in borosilicate glass is not feasible because of the very low solubility of fluorides in this host.Alternative candidates are thus an active topic of research including phosphatebased glasses,crystalline ceramics,and hybrid glass-ceramic systems.In this study,mixed fluorides were employed as simulated MSRs waste and incorporated into sodium aluminophosphate glass to obtain phosphate-based waste form.These waste forms were characterized by X-ray diffraction,Raman spectroscopy,and scanning electron microscopy.Leaching tests were performed in deionized water using the product consistency test A method.This study demonstrates that up to 20 mol%of simulated radioactive waste can be introduced into the NaA1 P glass matrix,and the chemical durability is much better than that of borosilicate.The addition of Fe_2O_3 in the NaAlP glass matrix results in increases of the chemical durability at the expense of fluoride loading(to 6.4 mol%).Phosphate glass vitrification of radioactive waste containing fluorides is a potential method to treat and dispose of MSR wastes.

Up-Conversion Properties of Oxy-Fluoride Glasses Co-Doped with Ho^(3+) and Yb^(3+)

Oxy-fluoride glasses with composition of 25SiO2-65PbF2-9.4AlF3-0.1HoF3-0.5YbF3 were prepared. Their up-conversion fluorescence characteristics were investigated by 980 nm laser. Two emission peaks were observed at 540 and 650 nm. The up-conversion mechanism and processes were analyzed. The relationship between pumping power and relative intensity of emissions was discussed. From the dependence, it is known that the emissions centered at 540 and 650 nm are both attributed to two-photon process.

Generation of Short Wavelength in Up-Conversion of Tm⁺³Doped Fluoride Glass and Its Application in Fiber Lasers

We report on the experimental study of the visible and ultraviolet (UV) fluorescence emission in a (1% molar) Thulium (Tm+3)-doped Zirconium fluoride glass sample. From red at 650 nm, blue (453 & 480 nm) and UV at 365 & 284 nm, have been observed under excitation of a Nd:YAG laser at 1.064 μm. The responsible up-conversion mechanisms are investigated based on experimental data. The related problem of photo-degradation associated with formation of color centers is also addressed.

Investigation on Preparation and Fluorescence Properties of Oxy-Fluoride Glass Co-Doped with Er^(3+) and Yb^(3+)

The glass sample based on the composition of 45PbF_2-45GeO_2-10WO_3 co-doped with Yb^(3+)/Er^(3+) was prepared by the fusion method in two steps: melted at 950 ℃ for 20～25 min then annealed at 380 ℃ for 4 h. Through the V-prism it is found that the refractive index of host glass and the sample are 1.517 and 1.65 respectively. The transmittance was observed by using the ultraviolet-visible-infrared spectrometer in the wavelength range from 0.35 to 2.5μm. The transmittance of the host glass is beyond 73%. That of the sample is beyond 50% and there are characteristic absorption peaks of rare-earth ions. The emission spectrum was measured by using the Hitachi F-4500 fluorescent spectrometer pumped by 980 nm semiconductor laser. There are a strong emission peak at 530 nm and a weak peak at 650 nm.

Studies on the Preparation and Properties of AIF_3－based Rare Earth Fluoride Glass

AlF3-REF3-AEF2 (RE: rare earth, AE: alkali earth) system fluoride glasses were prepared by quenching melts. The glass forming region of AlF3NdF3-(Mg0.25Ca0.25Sr0.25Ba0.25) F2 system was determined. Effects of AE and RE fluoride on the glass forming ability and thermal properties of the system have been discussed. The IR cut-off wavelength of AIF3-REF3-AEF3 glass is about 7 μm. This system has many advantages, such as low refractive index, high Abbe number, high Tg and Tc-Tg values, and good chemical durability, etc. This is a kind of new excellent ultra-low loss optical fiber and IR optical material.

S tudy on Doped Fluoride Glasses for Scintillation Applications

This paper studies the properties of fluoride glasses for use in particle calorimeters or in optical fibers. The effects of major and minor impurities in manufacturing process and ultimately on the glass properties have been investigated. Glasses in a range of compositions have been made and tested in the form of small samples as well as larger blocks of size 2×3×14 cm 3. Results of measurements on these materials, using a high energy particle beam, are presented.

FLUORIDE GLASSES CONTAINING RARE EARTH

Fluoride glasses containing rare earths exhibit interesting spectroscopic properties.They have wide transmission range from 0.25μm in the UV to 7μm in the IR,allowing observation,in a vitreous material,of absorption and emission bands in a large optical range.The absorption spectra of fluoride glasses with rare earth substitutions are found to vary with the rare earth ions used.The T_g~'s for these glasses average out at 311℃.Optical properties,such as refractive indices are not obviously influenced by rare earth substitutions.

Photostimulated Luminescence and Optical Storage in Eu ^(2+)-Doped Fluoride-Oxide Glass Ceramics

Photostimulated luminescence (PSL) phenomenon was observed in a fluoride-oxide glass ceramics doped with Eu 2+. When the UV light irradiated glass ceramic was stimulated by a longer wavelength light, PSL at 447 nm due to the 5d-4f transition of Eu 2+ was observed. The PSl excitation band peaking at 543 nm is due to the electron trap centers which are located either in the Eu 2+-doped crystallites or in the glass; where exactly they are located in is not yet known. The optical storage properties of this kind of glass ceramic were also studied. By comparing with the investigations on PSL phosphor Eu 2+ doped alkali halides, PSL mechanism in glass ceramics which is still an open question and has to be investigated in further experiments was explained.

Sensitized Up-Conversion Luminescence of Ho^(3+) in Nd^(3+)-Yb^(3+)-Ho^(3+) Co-doped ZrF_4-Based Glass

Up-conversion processes for the blue, green and red emissions were foundtwo-photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd^(3+)→ Yb^(3+) → Ho^(3+) energy transfer. The strong green emission due to the Ho^(3+) : (~5F_4, ~5S_2)→ ~5I_8 transitions was observed in Nd^(3+) - Ho^(3+) co-doped ZrF_4-based fluoride glasses under800 nm excitation. As an attempt to enhance Ho^(3+) up-conversion luminescences in the Nd^(3+) -Ho^(3+) co-doped ZrF_4-based glasses, Yb^(3+) ions were added to the glasses. As a result it wasfound that, in 800 nm excitation of 60ZrF_4. 30BaF2. (8-x)LaF_3. 1NdF_3. xYbF_3. 1HoF_3 glasses (x =0 to 7), sensitized up-conversion luminescences are observed at around 490 nm (blue), 545 nm(green), and 650 nm (red), which correspond to the Ho^(3+) : ~5F_3 → ~5I_8, ( ~5F_4, ~5S_2) →~5I_8 and ~5F_5 → ~5I_8 transitions respectively. The intensities of the green and red emissions ina 3 mol% YbF_3-containing glass were about 50 times stronger than those glasses without YbF_3. Thisis based on sensitization due to Yb^(3+) ions. In particular, the green emission was extremelystrong and the Nd^(3+) - Yb^(3+) - Ho^(3+) co-doped ZrF_4-based glasses have a high possibility ofrealizing a green up-conversion laser glass. In this paper the up-conversion mechanism in theglasses is discussed in detail.

Improved Fluorescence from Tm^3＋/Er^3＋/Ce^3＋ Triply Doped Bismuth-Silicate Glasses for S＋C-bands Amplifiers

Fluorescence of Tm^3＋/Er^3＋ codoped bismuth-silica （BS） glasses and the sensitization of Ce^3＋ are investigated, It shows that Ce^3＋ codoping with Tm^3＋/Er^3＋ in BS glasses results in a quenching of Tm^3＋ ion emission from ^3F4 to the ^3H6 level. Consequently, the 1.47μm emission occurs after the population inversion between the ^3H4 and ^3F4 levels. Furthermore, the codoped glasses show the broad emission spectra over the whole S and C bands with full-width at half-maximum （FWHM） up to about 119nm, as it combines 1.55μm emission band of Er^3＋ with 1.47μm emission band of Tm^3＋ under 800hm excitation.

Inhibition of sperm motility does not affect live-dead separation of bull sperm by glass beads

Aim: This study was designed to explore factors which influence binding of dead versus live sperm to glass filters.Methods: Multiple semen collections from bulls were used to explore selective filtration of bull sperm as influencedby nonlethal inhibition of sperm motility with fluoride, killing of sperm by quick-freezing, alteration of the glass sur-face with silicone, and different intervals of sexual rest between semen collections. Results: A comparison of glassspheres 100, 200 and 390μm in diameter indicated that 200 μm spheres were optimal for selective filtration. Quantita-tive separation of live from dead sperm was demonstrated with a correlation between the percentage of motile sperm andretention of sperm by the filter of r = -0.87 (P < 0.05). Up to 0.02 mol/L NaFl did not alter the proportion ofsperm retained by the filter despite inhibiting sperm motility during filtration, an inhibition which was reversible. Pro-portions of live-dead sperm, based upon eosin staining, were unaffected by fluoride. Coating the glass spheres with sil-icone greatly reduced selective filtration. Dead sperm adherence to glass was reduced and resistance to NaFl inhibitionwas increased by daily ejaculation versus one-week intervals of sexual rest. Conclusion; These studies indicate thatthe adherence of sperm to glass is primarily due to some form of physico-chemical change accompanying death of thesperm cell independent of active sperm motility. This attraction between the sperm plasma membrane and glass is modi-fied by the age of the ejaculated sperm. This information is useful in evaluating different clinical procedures used forsperm separation. (Asian J Androl 2001 Sep; 3: 193-198)

Thermal Analysis of Glasses in TeO2-BaF2-LaF3 Systems

Divalent metal fluorides MF2 （M=Sr, Mg, Ca） in oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were synthesized. The densities, refractive indices and characteristic temperatures of synthesized glasses were measured. The influence of divalent metal fluorides-MF2（M=Sr, Mg, Ca） on the thermal stability of oxyfluoride tellurite glasses TeO2-BaF2-LaF3 were studied. Results show that the replacement of BaF2 by SrF2 and MgF2 can enhance the thermal stability against crystallization of the glass. A glass system with good thermal stability was produced, which could be a potential candidate for the host materials of the fiber devices.

释氟充填材料在龋病防治中的研究进展

传统玻璃离子水门汀、树脂增强型玻璃离子水门汀、聚酸改性复合树脂、Giomer等牙科充填修复材料具有氟离子释放和再充氟能力,被认为可以预防或减缓龋病的进展。释氟充填材料的释氟能力、抗菌性、力学特性及抗老化特性都是评价其防龋能力的重要指标,材料的防龋作用主要依赖于氟离子对矿化的影响。但是,释氟能力强的材料如传统玻璃离子水门汀因力学性能欠佳等劣势主要用于儿童牙科及暂时修复,材料的氟离子释放潜力和机械强度很难两全,尚未有材料可以在提供理想机械强度的同时释放大量氟离子。传统玻璃离子水门汀、树脂增强型玻璃离子水门汀、聚酸改性复合树脂、Giomer的氟离子释放和再充氟能力依次递减,材料改性的趋势倾向于为维持理想的机械强度,一定程度上牺牲材料释放氟离子的能力。目前研究者们尝试通过添加多种无机填料进一步增强材料的抗折裂能力,通过添加抗菌剂补偿材料因氟离子释放减少损失的防龋作用。

Energy transfer mechanism in Er^(3+) doped fluoride glass sensitized by Tm^(3+) or Ho^(3+) for 2.7-μm emission

Enhanced 2.7 μm emission is obtained in Er3＋/Tma＋ and Era＋/Ho3＋ codoped ZBYA glasses. Absorp- tion and emission spectra are tested to characterize the 2.7 μm emission properties of Era＋/Tm3＋ and Era＋/Ho3＋ doped ZBYA glasses and a reasonable energy transfer mechanism of 2.7 μm emission between Er3＋ and Tm3＋Ho3＋） ion is proposed. Codoping of Tm3＋ or Ho3＋ significantly reduces the lifetime of the Era＋： 4I13/2 level due to the energy transfer of Er3＋：4I13/2 →Tm3＋：3F4 or Er3＋：4I13/2 →Ho3＋： 5I7. Thus, the 2.7μm emission is strengthened and the 1,5μm emission is decreased accordingly especially in the Era＋/Tma＋ sample. The upconversion effects between the Er3＋/Tm3＋ and Er3＋/Ho3＋ doped ZBYA glasses are different attribute to the different energy transfer efficiencies. Both of the two codoped samples possess nearly equal large emission cross section （16.6 × 10 -21 cm-2） around 2.7 μm. The results indicate that this Er3＋/Tm3＋ or Er3＋/Ho3＋ doped ZBYA glass has potential applications in 2.7 μm laser.

聚乙烯醇-聚偏氟乙烯共包裹玻璃微管的制备和性能研究

氢气是一种可替代化石能源的可持续,环境友好型能源。而安全有效的储氢、运氢方式是限制氢能大规模使用关键问题。玻璃微管(GT)作为轻质固态储氢材料具有质量轻、强度高、耐腐蚀性好、抗拉强度大等优点,但玻璃微管脆性大,在承受较大剪切力时,微管容易破损。因此,通过一锅法将聚乙烯醇(PVA)和聚偏氟乙烯(PVDF)共聚后包裹在玻璃微管表面,制得PVA-PVDF共包裹玻璃微管。利用复合聚合物的增强作用,可有效分散应力,提高材料的力学强度,尤其是提高包裹玻璃微管的剪切力断裂强度。包裹玻璃微管的剪切力断裂强度从5.4 MPa增强到8.2 MPa。

Comparative study of Sm^(3+) ions doped phosphate based oxide and oxy-fluoride glasses for solid state lighting applications

The physical and luminescent properties of Sm^(3+)-doped oxide and oxy-fluoride phosphate glasses were investigated. The glass samples with chemical composition of 69 P_2 O_5-10 BaO-10 ZnO-10 Gd_2 O_3-1 Sm_2 O_3 and 69 P_2 O_5-10 BaO-10 ZnO-10 GdF_3-1 Sm_2 O_3 were prepared by conventional melt quenching technique. The prepared glass samples were characterized with density, molar volume, refractive index,FTIR, UV-Vis-NIR, photo luminesce nce, radio luminescence, decay time profile and CIE diagram. The density and refractive index of the oxide glass have higher values as compared to the oxy-fluoride glass.The FTIR spectra show the reduction of O-H group in oxy-fluoride glass. The characteristic peaks of Sm^(3+)are observed at 360,372,402,438,419,473,944,1077,1227,1373,1474,1529 and 1585 nm in UV-VIS-NIR spectra. These peaks are related respectively to the transitions from ground state ~6 H_(5/2) to ~4 D_(3/2), ~6 P_(7/2),6 P3/2, ~4 I_(11/2), ~6 F_(11/2), ~6 F_(9/2), ~6 F_(7/2),~6 F_(5/2),~6 F_(3/2), ~6 H_(15/2) and ~6 F_(1/2) excited states. From photoluminescence and radio-luminesce nce it is observed that the oxy-fluoride glass samples show better emission intensity than the oxide glass. The Judd-Ofelt theory(J-0 theory) was used to find J-O intensity Ω_λ(λ = 2,4 and 6)parameters and radiative properties such as transition probability, stimulated emission cross section and branching ratios for titled glasses. The trend observed in the J-O parameters is Ω_4 >Ω_2 >Ω_6. The transition probability,emission cross section and branching ratio have the highest values for the ~4 G_(5/2)→~6 H_(7/2)transition. The CIE coordinates of the prepared glass samples are positioned in the orange region and the CCT value is 3776.105 for oxide and oxyfluoride glass. The oxy-fluoride glass has shorter decay time as compared to the oxide glass and it is recorded to be 1.62 and 1.32 ms for oxide and oxy-fluoride respectively. According to the results obtained in this work, it is obvious that these glass samples can be good candidate materials for producing cool orange light.