High Temperature Melt-quenching Method Research Articles

Study on luminescent performance of Dy3+-, Tb3+-doped and Tb3+/Dy3+ co-doped TeO2-(Gd,Lu)2O3-WO3 glass scintillators

Three series of Dy3+-, Tb3+-doped and Tb3+/Dy3+ co-doped 40TeO2-20(Gd,Lu)2O3–40WO3 glasses with density of about 6.75 g/cm3 were successfully prepared by high temperature melt-quenching method. The luminescence properties of these rare earth ions doped 40TeO2-20(Gd,Lu)2O3–40WO3 glass were systematically studied by transmittance, photoluminescence (excitation and emission spectra), time-resolved emission spectra (TRES) and X-ray excited luminescence (XEL) spectra, together with the luminescence decay curves. The optimal doping concentration of Dy3+ and Tb3+ ions in 40TeO2-20(Gd,Lu)2O3–40WO3 glasses was determined under UV and X-ray excitation, respectively. It is found there is an efficient energy transfer from Dy3+ to Tb3+ ions in 40TeO2-20(Gd,Lu)2O3–40WO3 glass in photoluminescence spectra. However, it is not true under X-ray excitation due to the complicated physical process.

Color tuneability behaviour and energy transfer analysis on Dy3+-Eu3+ co-doped glasses for NUV-WLEDs application

A series of Dy3+ and Eu3+ co-doped zinc aluminoborosilicate (ZABS) glasses were synthesized by a high-temperature melt-quenching method. Visible and NIR transitions of Dy3+-Eu3+ ions are observed through absorption spectra. A reverse trend in the optical band gap values and Urbach energy are seen with addition of Eu3+ ions. Photoluminescence studies recorded under different excitation wavelengths showed a variation in the emission intensities and prevailed the color tuneability behaviour of dopants. The energy transfer between Dy3+ and Eu3+ ions are studied through emission profiles, energy level diagram, and decay curves. The type of multipolar interaction between Dy3+ and Eu3+ are understood via Inokuti-Hirayama (IH) model and Dexter energy model. The CIE chromaticity coordinates, and correlated color temperature (CCT) values suggest that the prepared glasses can be used for light emitting diode application when excited at near-ultraviolet region.

Original KGd2F7 nanocrystals in fluoro-oxide glass ceramics by Dy3+/Sm3+ co-doped for white light emission

Serial fluoro-oxide glass ceramics (GCs) containing 0.6 mol% Dy 3+ and various Sm 3+ from 0 mol% to 1.5 mol% co-doped novel KGd 2 F 7 nanocrystals were firstly fabricated through high temperature melt-quenching method. Then the microscopic structure of the GCs was revealed by transmission electron microscopy (TEM). And the rare-earth ions (RE 3+ ) of Dy 3+ and Sm 3+ were successfully doped in monoclinic-phase KGd 2 F 7 nanocrystals, which can be verified by energy-dispersive X-ray spectroscopy (EDX) mappings. The photoluminescence spectra of the GCs were probed systematically utilizing 365 nm excitation light. The yellow (573 nm), green (486 nm), and red (648 nm) multiple emissions were observed in the co-doped GCs, and the intensity of red became stronger because of the higher Sm 3+ doping concentrations. This contribution of multiple emissions is due to the co-absorption of both Dy 3+ and Sm 3+ for 365 nm and the presence of energy transfer (ET). Moreover, the ET between Dy 3+ and Sm 3+ was confirmed from the variations of emission spectra and measured decay curves of emissions. Furthermore, the maximum energy transfer efficiency (ETE) from Dy 3+ to Sm 3+ can reach ~60.34% and the internal quantum yield (QY) is computed to be around 31.82% upon excitation of 365 nm. The chromaticity coordinates (CIE (Commission Internationale de L′Eclairage)− 1931) of the GCs can be tuned effectively through changing activator concentrations. Ideal white light emission is at the CIE (0.3357, 0.3342), which was achieved for 0.6 mol% Dy 3+ /0.9 mol% Sm 3+ doped GCs sample. The results indicated that Dy 3+ /Sm 3+ co-doped GCs with both high thermal and chemical-physical stabilities have strong potential application in white light-emitting diodes and fluorescent display devices. • The Dy 3+ /Sm 3+ co-doped fluoro-oxide glass ceramics containing novel KGd 2 F 7 nanocrystals were firstly fabricated. • The Dy 3+ and Sm 3+ ions were successfully doped in monoclinic-phase KGd 2 F 7 nanocrystals. • The standard white light emission was obtained by changing the concentration of Sm 3+ . • The energy transfer process from the Dy 3+ to Sm 3+ has been verified to dipole-dipole interaction mechanism. • The fluoro-oxide glass ceramics containing KGd 2 F 7 nanocrystals exhibit high thermal stability.

Luminescence tuning of Tb/Eu Co-doped zinc aluminoborosilicate glasses for white LED applications

Tb3+/Eu2+,3+-doped zinc aluminoborosilicate glasses were prepared using a conventional high temperature melt-quenching method. Infrared spectra and physical properties of as-prepared glasses verified that the addition of Tb/Eu causes structural weakness in the glass. Tuning of blue, green, and red emission bands achieves white light for the zinc aluminoborosilicate glasses. The broad blue emission band is attributed to the 5d-4f transition of Eu2+ due to partial reduction of Eu3+ during calcination in ambient atmosphere. The reduction of Eu3+ is related to the formation of EuZn• and VZn'' defects and host alkalinity decreases with the addition of Eu3+. Emission spectra and decay curves confirm energy transfer from Tb3+ to Eu3+ in the zinc aluminoborosilicate glasses, and relative intensities of green and red luminescence can be tuned through concentrations changes of Tb3+ and Eu2+,3+. When the concentrations of Tb3+ and Eu2+,3+ are equal to 6% and 1.2%, respectively, a neutral white light emitting glass is obtained. Furthermore, the white-emitting glass shows very high thermal stability compared to a commercial Y3Al5O12:Ce3+ phosphor. Therefore, luminescence tuning of glasses through changing activator concentrations and energy transfer is expected to achieve high-powered white LEDs.

Enhanced emission intensity of Ce3+-doped aluminoborosilicate glasses prepared in air

A convenient and effective strategy of preparing the colorless and transparent Ce3+-doped aluminoborosilicate glass in air by high temperature melt-quenching method is revealed. It is easily achieved by the partial substitution of Si3N4 for SiO2 within 20–25 mol%. The optimized Ce3+-doped aluminoborosilicate glass scintillaor (y = 25%) is featured with a density of 4.6432 g/cm3 and a lifetime of 35.36 ns, respectively. Compared to the glass without any substitution of Si3N4 (y = 0%), both the photo- and radio-luminescence intensity of the optimized Ce3+-doped aluminoborosilicate glass (y = 25%) are enhanced by a factor of 11.05 and 10.58, respectively. The corresponding integrated raidoluminescence intensity is about 22.8% of that of BGO crystal irradiated by X-rays.

Dual-mode downconversion luminescence with broad near-ultraviolet and blue light excitation in Tm3+/Yb3+ codoped oxy-fluoride glasses for c-Si solar cells

In this work, we demonstrated an efficient dual-mode solar spectral converter Tm3+/Yb3+ co-doped oxy-fluoride glasses synthesized using high temperature melt-quenching method. The transmittance, photoluminescence emission (PL) and photoluminescence excitation (PLE) spectra and decay dynamics have been systematically investigated. The experimental results revealed that two distinct solar spectral converting processes, quantum cutting (QC) and down-shifting (DS) were achieved through the sensitization of Tm3+ excited multiplets and a broad band attributing to Yb3+-O2− charge transfer state (CTS), respectively. The prepared materials could convert the UV (250–370 nm) and blue (450–490 nm) photons into broad NIR emission (900–1100 nm), which coincides well with the most efficient spectral response of Si-based solar cells. The resultant Tm3+/Yb3+ co-doped oxy-fluoride glasses with dual-mode solar spectral modification indicate its potential application in improving the energy conversion efficiency of Si-based solar cells.

Effect of Eu3+ ions on optical and fluorescence studies of Nd3+ ions doped zinc-lithium fluoroborate glasses

Nd3+ single and Nd3+/Eu3+ co-doped ZnF2-LiF-Na2CO3-Bi2O3-H3BO3, zinc lithium fluoroborate (ZLFNBiB) glasses with good optical properties have been prepared by high temperature melt-quenching method. The single and co-doped samples exhibiting emission bands centered at 874, 1058 and 1330 nm under the excitation of 808 nm laser diode (LD). The photoluminescence spectra for co-doped glasses were recorded under the 394 and 464 nm of xenon lamp as excitation sources. The Judd-Ofelt intensity parameters were calculated from optical absorption spectrum and radiative parameters from the emission spectrum of 0.5 mol% of Nd3+ doped glass. The large stimulated emission cross-section and branching ratio values are evaluated and compared with the other Nd3+ doped systems, the energy transfer from Eu3+ to Nd3+ ions is observed and thoroughly discussed from NIR emission spectra (λexc = 394 nm) of co-doped glasses. The decay profiles are recorded for all the concentrations of co-doped samples and the experimental lifetimes (τexp) were obtained from the decay profiles. The binding energy and Urbach energy values of prepared glass samples were calculated and discussed.

Spectroscopic Properties of Yb3+/Nd3+ Co-doped Ions in SiO2-Al2O3-Na2CO3-SrF2-CaF2 Oxyfluoride Glasses for Photonic Applications

The Yb3+ and Yb3+/Nd3+ co-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 oxyfluorosilicate glasses have been prepared by high temperature melt-quenching method. The prepared glasses are excited with 808 nm, and the near infrared emission bands are observed. The intensified emission band was centered at 1030 nm (2F5/2 -> 2F7/2) of Yb3+ ions. Stimulated emission cross-section was evaluated for the prominent 2F5/2 -> 2F7/2 transition of Yb3+ ion by using the Mc-Cumber theory. The energy transfer from Nd3+ to Yb3+ ions in co-doped silicate based oxyfluoride glasses are described under the 514 nm excitation wavelength. Full Text: PDF ReferencesN. Chiodini, A. Paleari, G. Brambilla, E. R. Taylor, "Erbium doped nanostructured tin?silicate glass?ceramic composites", Appl. Phys. Lett. 80, 4449 (2002). CrossRef D. Jaque, J. Capmany, F. Molero, Z. D. Luo, J. G. Sole, "Up-conversion luminescence in the Nd3+:YAB self frequency doubling laser crystal", Opt. mater. 10, 211 (1998). CrossRef H. Lin, G. Meredith, S. Jiang, X. Peng, T. Luo, N. Peyghambarian, E. Yue-Bun Pun, "Optical transitions and visible upconversion in Er3+ doped niobic tellurite glass", J. Appl. Phys. 93, 186 (2003) CrossRef Atul D. Sontakke, K. Annapurna, "Phonon assisted effective non-resonant energy transfer based 1 ?m luminescence from Nd3+?Yb3+ codoped zinc?boro?bismuthate glasses", J. Lumin. 138, 229 (2013). CrossRef F. Liegard, J.L. Doualan, R. Moncorge, M. Bettinelli, "Nd3+ ? Yb3+ energy transfer in a codoped metaphosphate glass as a model for Yb3+ laser operation around 980 nm", Appl. Phys. B 80, 985 (2005) CrossRef A. Miguel, B. Fan, R. Balda, X. Zhang, J. Fernandez, J.L. Adam, "Spectroscopy and energy transfer in Nd3 +/Yb3 + codoped chalcohalide glasses", J. Non-Cryst. Solids 377, 110 (2013). CrossRef G. Devarajulu, B. Deva Prasad Raju, "Effect of concentration variation on 2.0 ?m emission of Ho3+-doped SiO2?Al2O3?Na2CO3?SrF2?CaF2 oxyfluorosilicate glasses", App. Phy. A, 124 (2018). CrossRef Radoslaw Lisiecki, Elzbiecta Augustyn, Witold Ryba-Romanowski, Michal Zelechower, "Er-doped and Er, Yb co-doped oxyfluoride glasses and glass?ceramics, structural and optical properties", Opt. Mater. 33, 1630 (2011). CrossRef G. Chen, Q. Zhang, G. Yang, and Z. Jiang, "Mid-Infrared Emission Characteristic and Energy Transfer of Ho3+-Doped Tellurite Glass Sensitized by Tm3+", J. Fluoresc. 17, 301 (2007). CrossRef D. E. McCumber, "Theory of Phonon-Terminated Optical Masers", Phys. Rev. 134, 299 (1964). CrossRef D.L. Deloach, S.A. Payne, L.K. Smith, W.L. Kway, W. F. Krupke, "Laser and spectroscopic properties of Sr5(PO4)3F:Yb", J. Opt. Soc. Am. B 11, 269 (1994). CrossRef K. Venkata Krishnaiah, R. Rajeswari, K. UpendraKumar, S. Surendra Babu, I.R. Martin, C.K. Jayasankar, "Spectroscopy and radiation trapping of Yb3+ ions in lead phosphate glasses", J.Quant. Spect. Rad. Trans. 140, 37 (2014). CrossRef

Efficient 2.0 μm emission in Nd3+/Ho3+ co-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 glasses for mid-infrared laser applications

Nd3+/Ho3+ co-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2-Ho2O3-Nd2O3 oxyfluorosilicate glasses have been prepared by high temperature melt-quenching method. The co-doped samples exhibit fluorescence bands centered at 892, 1058, 1330 nm and 2.0 μm under the excitation of 808 nm laser diode (LD). The energy transfer mechanism between Nd3+ and Ho3+ was analyzed based on the absorption, emission and the energy level structures of Nd3+ and Ho3+ ions. In the present investigation, the energy transfer efficiency from Nd3+ to Ho3+ reached ∼50% under the excitation of 808 nm. This result indicates that Nd3+ ions can be potentially used as sensitizers for Ho3+ ions to stimulate the NIR emissions. Stimulated emission cross-section was evaluated for the prominent 5I7 → 5I8 transition of Ho3+ ion by using the Mc-Cumber theory. The spectroscopic characteristics of Nd3+/Ho3+ co-doped oxyfluorosilicate glasses are found to be suitable as optical medium for mid infrared emission at ∼2.0 μm.

Structural characterization and temperature-dependent luminescence of CaF2:Tb3+/Eu3+ glass ceramics

Tb3+/Eu3+ co-doped transparent glass ceramics containing CaF2 nanocrystals were successfully synthesized by high temperature melt-quenching method and subsequent heating. The structure and morphology of the samples were investigated by X-ray diffraction (XRD), transmittance electron microscopy (TEM), high resolution TEM (HRTEM) and selected area electron diffraction (SAED). The photoluminescence properties and energy transfer process from Tb3+ to Eu3+ of CaF2:Tb3+,Eu3+ phosphors were also investigated through excitation spectra and decay curves. In addition, the emission spectra of the glass ceramics in a wide temperature range from 21 to 320 K were recorded under the excitation of 485 nm. It was found that the fluorescence intensity ratios of Tb3+ at 545 nm (5D4→7F5) to Eu3+ at 615 nm (5D0→7F2) was highly temperature-dependent with an approximate linear relationship, and the temperature sensitivity was about 0.4%/K. It is expected that the investigated Tb3+/Eu3+ co-doped CaF2 glass ceramics may have prospective application in optical thermometry.

Efficient 2 µm emission in Nd3+/Ho3+ co-doped silicate-germanate glass pumped by common 808 nm LD

Nd3+/Ho3+ co-doped silicate-germanate glass has been synthesized by high temperature melt-quenching method. Near infrared emission centered at 2µm has been successfully obtained by incorporating Nd3+ and Ho3+ in present glass. The Judd-Ofelt intensity parameters Ωt (t=2, 4, 6), and radiative properties of Ho3+ were calculated and discussed by using the Judd-Ofelt theory. The energy transfer processes and luminescence properties of Nd3+/Ho3+ co-doped glasses were analyzed pumped by a conventional 808nm laser diode. Desirable spectroscopic characteristics indicates that Nd3+/Ho3+ co-doped silicate-germanate glass might be a good alternative matrix for 2µm band mid-infrared laser.

Enhanced solar photons harvesting of a-SiC:H solar cells with ZBLA fluoride glasses containing rare earth ions

As encapsulation glasses for a-SiC:H cells, Yb3+/Ce3+-Er3+ tri-doped ZBLA fluoride glasses were prepared using the high temperature melt-quenching method and the optical characteristic of the glass were measured. Depending on the nature of rare earth doped ZBLA fluoride glasses, both near infrared (low-energy) and ultraviolet (high-energy) solar photons can be transformed into visible photons. By downshifting the ultraviolet (280–350 nm) light combined with upconverting the near infrared (900–1100 nm) light, the glass can emit strong visible (500–700 nm) light, which matches well with the spectral responsivity of a-SiC:H cells. The conversion of non-absorption photons energies by upconversion and downshifting leads to promote the improvement of a-SiC:H cells performances, and measurement shows relatively increase of 7.6%–0.8% in cell efficiencies.

Scintillation properties of Ce3+ doped SiO2-Al2O3-Gd2O3 glass

Scintillation glass is an attractive material due to its many advantages including low-cost and easy-manufacturing compared with single crystal. However the low density of glass scintillator restricts its applications. The introduction of heavy components such as PbO and Bi2O3 allows the density of the glass to be easily increased to more than 6.0 g/cm3 which is desirable for most applications. However, it is usually accompanied with a dramatic decrease in the luminescence response of Ce3+ ions. Although Gd2O3 based glass has a relatively high light yield, it is far below the high silica glass. In order to explain why the luminescent efficiency of Ce3+ doped glass with low density is high while that with high density is low, a glass-forming region of SiO2-Al2O3-Gd2O3 ternary system is achieved by high-temperature melt-quenching method. Ce3+doped SiO2-Al2O3-Gd2O3 and SiO2-Al2O3-Gd2O3-Ln2O3 (Ln=Y, La, Lu) scintillation glasses are prepared at reducing atmosphere. Their optical and scintillation properties are investigated. The results show that the content of Gd2O3 can reach as high as 30% mol without phase separation. In addition, the UV cut-off position is red-shifted, PL intensity decreases and decay time reduces from 70 to 37.6 ns with increasing the Gd2O3 concentration. After Lu2O3, La2O3, Y2O3 are added in the glass, the UV cut-off position is red-shifted and PL intensity decreases. Moreover the UV cut-off position is in the order of La>Y>Lu and the decay time is in the order of La2O3 is more than 10% mol, X-ray excited luminescence light emission intensity reduces from 61% of BGO to 13% of BGO. With the UV cut-off position red-shifted, the bandgap of glass becomes narrow, resulting in the 5 d level of Ce3+ ions gradually approaching to the conduction band and the 5 d electrons easily combining with the holes in the glass through the conduction band. Namely, charge transferring quenching occurs. This is the reason why the PL intensity and decay time both decrease. It can also explain why the luminescent efficiency of Ce3+ doped glass with low density is high while that with high density is low.

Modeling and simulation of mid-IR amplifying characteristics of Tm3+-doped chalcogenide Photonic Crystal Fibers

This paper deals with the designing of a Tm3+-doped chalcogenide Photonic Crystal Fiber (PCF) amplifier operating in the mid-IR range. The chalcogenide glass of 72GeS2–18Ga2S3–10CsI (in mol%) was fabricated with the high temperature melt-quenching method, which exhibited a strong emission peak around 3.8μm under the excitation of a 800nm laser. By employing the rate equations and propagation equations, the amplifying characteristics of the designed PCF amplifier were worked out. It is shown that the designed PCF amplifier exhibits a signal gain larger than 30dB and a spectral width wider than 200nm. The theoretical models and simulation results show that the PCF presented in this work can be used in developing high efficiency mid-IR light sources.

Properties of luminescence and scintillation of Eu-doped high gadolinium glass

Eu (1 wt%) doped 15SiO2-25B2O3-30Al2O3-30Gd2O3 oxide glasses are prepared by high-temperature melt-quenching method in air and reduced atmosphere, respectively. The properties of scintillation and photoluminescence of the two samples are compared. When the samples fabricated in reduced atmosphere are excited by the X-ray and 395 nm violet light, a 450–550 nm blue-green light beam from Eu2+ and a 615 nm red light beam from Eu3+ are obtained. The intensity ratios between Eu3+ and Eu2+ are obviously different under different excitation sources. The intensity ratio under the excitation of the 395 nm violet light is 0.02 while it increases to 1.37 under the X-ray excitation. By analyzing the phonon sideband spectra of the samples, it is found that the Eu3+ ions around the former of Si are completely reduced into Eu2+ ions, while only part of Eu3+ ions around the former of B and Al are reduced into Eu2+ ions. Further investigation about the scintillation mechanism indicates that the sensitization of Gd and the energy transfer of Eu2+→Eu3+ near the formers of B and Al increase the scintillation performances of Eu3+ ions in the reduced glass samples.

Fabrication of erbium-doped chalcogenide glass and study on mid-IR amplifying characteristics of its microstructured fiber

In order to demonstrate the characteristics of chalcogenide glass Er3+-doped microstructured optical fiber (MOF) amplifying the mid-infrared band signal, Er3+-doped Ga5Ge20Sb10S65 chalcogenide glass is prepared with high temperature melt-quenching method. The absorption spectrum and 2.7 m band fluorescence spectrum of glass sample are measured, and the spectroscopic parameters such as radiative transition probability, radiative lifetime and 2.7 m band stimulated emission cross-section of Er3+ ion are calculated and analyzed according to the Judd-Ofelt and Futchbauer-Ladenburg theories. The 2.7 m band mid-infrared signal amplifying model of Ga5Ge20Sb10S65 chalcogenide glass Er3+-doped MOF under the excitation of 980 nm is presented, and the amplifying characteristics of 2.7 m-band mid-infrared signals for chalcogenide glass Er3+-doped MOF are investigated theoretically. The results show that the chalcogenide glass Er3+-doped MOF exhibits a higher signal gain and very broad gain spectrum: its maximal gain of small signal exceeds 40 dB and amplifying bandwidth of higher than 30 dB gain reaches about 120 nm (26962816 nm) for a 100 cm long chalcogenide glass erbium-doped MOF with a pump power of 200 mW. The theoretical studies indicate that the Ga5Ge20Sb10S65 chalcogenide glass Er3+-doped MOF is an excellent gain medium which can be applied to broadband amplifiers in the mid-infrared wavelength region.

Synthesis and luminescence properties of glass ceramics containing MSiO 3:Eu 2+ (M=Ca, Sr, Ba) phosphors for white LED

Eu 2+ doped silicate glasses were prepared of the system 52SiO 2–48MO: xEu 2+(in molar ratio, M=Ca, Sr, Ba; x=1, 3, 5, 7, 9) by a high temperature melt-quenching method in a reducing atmosphere. Glass ceramics containing MSiO 3:Eu 2+(M=Ca, Sr, Ba) nano-phosphors were obtained after the heat treatment of the glass samples. The excitation, emission spectra and lifetime decay curves of 4f 65d 1→4f 7 of Eu 2+ were measured and interpreted with respect to their crystal structures and multi-site occupations of divalent europium in the hosts. Their excitation bands mainly extend from 450 to 250 nm, which is adaptable to the main emission region of the UV LED chip. With UV light excitation, the Eu 2+ emission in CaSiO 3, SrSiO 3 and BaSiO 3 shows blue, green and yellow colors centered at 440, 505 and 555 nm, respectively. The critical Eu 2+concentration was studied and determined to be x=5 for both CaSiO 3 and SrSiO 3 and x=7 for BaSiO 3 phosphors. The results show that the Eu 2+ doped glass ceramic phosphors containing MSiO 3 (M=Ca, Sr, Ba) nano-crystals can be used as potential matrix materials for a high power white LED pumped by the UV LED chip.

Effect of hydroxyl groups in erbium-doped tellurite- and bismuth-based glasses

Tellurite- and bismuth-based glasses with the composition of TeO 2–B 2O 3–GeO 2–Na 2O–Er 2O 3 and Bi 2O 3–B 2O 3–GeO 2–Na 2O–Er 2O 3, respectively, were prepared by the conventional high-temperature melt-quenching method. Infrared spectra were measured in order to investigate the effects of glass composition and bubbling oxygen treatment on the vibration absorptions of OH groups. The constants K OH–Er for Er 3+ in tellurite- and bismuth-based glasses, which represent the interaction strength between Er 3+ and OH groups in the case of energy migration were calculated, and the effects of OH groups upon the fluorescence lifetimes of 4I 13/2 level and the emission intensities at 1.5 μm band of Er 3+ in both glasses were investigated and compared in detail under different oxygen bubbling time.