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Dy <sup>3+</sup> -doped Y <sub/>3</sub> Al <sub/>5</sub> O <sub/>12</sub> transparent ceramic for high efficiency ultraviolet excited single-phase white-emitting phosphor
摘要： A kind of Dy-doped yttrium aluminum garnet (YAG) transparent ceramic for ultraviolet excited single-phase white light emitting phosphor was investigated, which has high quantum efficiency (45%). The temperature field of Dy:YAG transparent ceramic was calculated by steady state thermal simulation. Moreover, by combining with 365 nm LED chip directly, the CIE coordinate (x=0.33, y=0.35) is close to the standard equal energy white light illumination. The Dy:YAG transparent ceramic, possessing of good optical and thermal properties, is promising for applications in high-power LEDs devices.
关键词： single-phase white-emitting phosphor,Dy-doped YAG,high-power LEDs,transparent ceramic
更新于2025-09-09 09:28:46
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Co-precipitation synthesis, structural characterization and fluorescent analysis of Nd3+ doped Y3Al5O12 and Yb3Al5O12 nanocrystallines
摘要： Nd3+, as one of the most important rare-earth (RE) ion, has been playing a significant role in pumping the infrared (IR) light. Depending on different synthesis strategies, doping content, and crystal lattice, however, Nd3+ always shows different IR intensity. In this work, we have fabricated two series of Nd3+ doped nanocrystallines that share with the same crystal structure, i.e., Nd3+ doped Y3Al5O12 (YAG) and Yb3Al5O12 (YbAG), through using the co-precipitation synthesis method while the ammonium bicarbonate as the precipitant agent. To reveal the influence of the synthesis conditions (e.g., synthetic temperature and pH value) on structural and florescent properties of Nd3+ doped YAG and YbAG nanocrystallines, several techniques have been performed in this work, including the X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric-differential scanning calorimeter (TG-DSC), Fourier transform infrared (FT-IR) spectroscopy, Raman and florescent spectroscopy spectra. Our results reveal that the optimal synthesis conditions are 1000?°C and pH 8 for YAG:Nd3+ and 900?°C and pH 9 for YbAG:Nd3+. Moreover, we also find the optimal Nd3+ doping contents of the YAG:Nd3+ and YbAG:Nd3+ nanocrystallines are 3% and 1.5%, which correspond to the strongest fluorescent intensity upon excitation at 808?nm and 980?nm, respectively. Typically, we reveal that substitution of Y with Yb ions could allow to enhancing the Nd3+ fluorescent intensity upon excitation at 808?nm. This work provides new insights into designing excellent crystal materials that can allow us to realize the laser transparent ceramics.
关键词： Nd3+ doped YbAG,fluorescent analysis,Nd3+ doped YAG,co-precipitation synthesis,structural characterization
更新于2025-09-09 09:28:46
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Crystal Growth and Scintillation Properties of YAG:Ce3+ for γ and α Detection
摘要： A bulk single crystal of yttrium aluminum garnet (Y3Al5O12:Ce3+, YAG:Ce3+) with good optical quality and free of cracks has been grown successfully by the Kyropoulos method. The dimension of the as grown crystal boule was ? 20 × 30 cm3. The cut and polished crystal sample of dimensions 1 × 1 × 0.5 cm3 was used for further measurements. The phase purity was confirmed by powder X-ray diffraction pattern analysis. The scintillation properties, such as X-ray emission spectrum, pulse height spectra, energy resolution, and scintillation decay time, were investigated using a 137Cs γ-ray source. The recorded X-ray emission spectrum shows a broad band between 500 and 700 nm with a peak at around 540 nm, which is attributed to the 5d-4f transition of the Ce3+ ion. The pulse-shape discrimination (PSD) of α and γ signals in a YAG:Ce3+ crystal has been studied by using different pulse shapes. The grown YAG:Ce3+ crystal which is non-hygroscopic, chemically inert, fast inorganic scintillator could be used for radiation detection application in nuclear, and high energy physics.
关键词： YAG:Ce3+ crystal,Kyropoulos method,Pulse shape discrimination,Radiation detector
更新于2025-09-09 09:28:46
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Effect of heat input in pulsed Nd:YAG laser welding of titanium alloy (Ti6Al4V) on microstructure and mechanical properties
摘要： In the present investigation, titanium alloy Ti6Al4V of 1.4 mm thickness has been laser-welded in butt joint configuration using pulsed Nd:YAG laser system. The effects of heat input on weld bead shape, fusion zone width (top, middle, and bottom), heat-affected zone (HAZ) width (top, middle, and bottom), and fusion zone area have been studied. The microstructure and mechanical properties of laser-welded specimens at various heat inputs (43.7–103.5 J/mm) have also been investigated. Microstructures of the fusion zone, HAZ, and parent material have been compared at various heat inputs using optical microscope and field emission scanning electron microscope (FESEM). The mechanical properties such as microhardness and tensile strength of the welded joints at varying heat inputs have been studied. Tensile tests of the welded specimen and base metal have been conducted for analyzing ultimate tensile strength and percentage elongation. Surface topography of the tensile fractured specimen of the welded joints and base metal has been examined to analyze the ductile and brittle behavior. EDS analyses of base metal and fusion zone of the welded specimen have been studied. XRD of the as-received base metal and welded specimen have been measured in the range of 30 to 85° to study the crystallographic structure.
关键词： Ti6Al4V,Microstructure,Laser beam welding,Pulsed Nd:YAG laser,Microhardness,Porosity
更新于2025-09-04 15:30:14
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High Pressure effect on fluorescence lifetime <i>τ</i> for magnetic dipole <sup>5</sup> D <sub/>0</sub> → <sup>5</sup> F <sub/>1</sub> transitions in YAG:Eu <sup>3+</sup>
摘要： The fluorescence lifetime for magnetic dipole 5D0→7F1 transition in yttrium aluminum garnet doped with Eu3+ (YAG:Eu3+) crystal was studied under the pressure of up to 10.4 GPa at room temperature. The fluorescence lifetime τ (5D0→7F1 transition) slowly decreased with pressure. The pressure effect on τ (5D0→7F1 transition) was explained with a model which considered pressure effect on line position: inter-ionic distance, ion volume, molecular volume, ion polarizability, molecular polarizability, sample refractive index, and surrounding hydrostatic medium refractive index. The fluorescence lifetime τ calculated by the presented model was in close correspondence with the experimental values.
关键词： rare earth,fluorescence lifetime,YAG:Eu3+,optical properties,glass ceramics,High pressure
更新于2025-09-04 15:30:14
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Physicochemical Processes in the Synthesis of New Detectors of X-Ray Radiation Based on YAG:Ce-Halide Fluxes
摘要： Using the data of X-ray phase analysis, optical spectroscopy, and scanning electron microscopy of YAG:Ce luminophores, the main types of interactions in complex systems formed by a light-emitting diode luminophore and halide fluxing agents are determined, which cause intense luminescence in the ultraviolet region.
关键词： luminophores,UV luminescence,halide fluxes,YAG:Ce
更新于2025-09-04 15:30:14
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Frequency-Modulated Pulse-Amplification Method for Reducing Pulse Shape Distortion
摘要： To reduce the laser pulse shape distortion accompanying the ampli?cation process and achieve an intended output pulse shape in the Nd:YAG ampli?er chain, we propose a frequency-modulated pulse-ampli?cation method. Assuming carrier-frequency-modulated seed pulses, we numerically simulate the pulse ampli?cation in an Nd:YAG ampli?er chain where severe distortion occurs. For the calculation, we develop a modi?ed Frantz-Nodvik equation, which enables two inputs with di?erent carrier frequencies. The simulation results indicate that the temporal contrast of the seed pulse needed to obtain a ?at output pulse shape is reduced by 16 - 25 dB when frequency modulation is applied.
关键词： Nd:YAG,Pulse shaping,Pulse distortion,Frequency modulation
更新于2025-09-04 15:30:14
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The impact of Eu3+ ion substitution on dielectric properties of Y3?xEuxAl5O12 (0.00?≤?x?≤?0.10) ceramics
摘要： This study reported the effect of Eu substitutions on the conductivity and dielectric properties of Y3?xEuxAl5O12 (0.0 ≤ x ≤ 0.1), YAG:xEu3+. All products were fabricated by solid state route. The formation of YAG was approved through X-ray diffraction powder diffraction and high-resolution transmission electron microscope. It was found that the lattice parameters are increasing with increase the substitution content due to the difference in ionic radii between Y3+ and Eu3+. Electrical and dielectric properties of YAG (Y3Al5O12) and YAG:xEu3+ ceramics were investigated extensively for a variety of concentrations (0.00 ≤ x ≤ 0.1) of the substitutional Eu3+ ion from the 4f lanthanide group. The temperature dependence of dielectric loss, dielectric constant, loss tangent and ac/dc conductivity were examined up to 5.0 MHz to understand the electrical and dielectric properties for both doped and undoped YAG ceramics. The experimental results revealed that Eu3+ ion substitutions (especially x = 0.05) in YAG ceramics meaningfully influence the lossy mechanisms, conductivity and dielectric constant which is probably due to the contribution to the conduction mechanism of the 4f–Eu and 3d–Al ions. So, this can be incorporated at the exceptional sites of both Oh (octahedral) and Td (tetrahedral) symmetries in YAG: xEu3+ ceramics.
关键词： conductivity,solid state route,YAG,dielectric properties,Eu3+ ion substitution
更新于2025-09-04 15:30:14
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Anomalous passive Q-switching induced by Cr <sup>4+</sup> :YAG: with pulse repetition rate approaching up to 1 MHz
摘要： Anomalous passive Q-switching behavior was demonstrated in an Yb:KLu(WO4)2 laser, with a Cr4+:YAG crystal plate acting as saturable absorber whose initial transmission amounted to 99.3%. In stable Q-switched operation realized under high output coupling of 80%, 1.83 W of average output power was produced at a pulse repetition rate of 0.97 MHz, far beyond the upper limit imposed by the recovery time of the saturable absorber. The largest pulse energy, shortest pulse duration, and highest peak power were, respectively, 1.89 μJ, 39 ns, and 48.5 W. The high-repetition-rate passive Q-switching performance shows a close similarity to some Yb-ion lasers passively Q-switched by 2D saturable absorbers.
关键词： Cr4+:YAG,Yb lasers,passive Q-switching,Yb:KLuW crystal
更新于2025-09-04 15:30:14