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Luminescence properties of Nd3+ ions doped P2O5-Li2O3-GdF3 glasses for laser applications
摘要： The phosphate glass doped with Nd3+ ions, is a recognized high gain laser material due to better spectroscopic properties. In present study, the luminescent properties of Nd3+ doped lithium-gadolinium phosphate glasses were investigated. The compactness of the glass matrix believed to increase with increasing concentration of Nd2O3 contents, because the density of the samples also increases in same fashion. Furthermore, the emission spectra monitor after 804 nm excitation show three emission peaks at 874, 1065 and 1333 nm. In the present work maximum emission intensity recorded for 1 mol% of Nd2O3 and above 1 mol% the emission intensity decrease. The Judd-Ofelt (JO) theory applied to calculate the JO intensity parameters (Ω2, 4, 6), oscillator strength for absorption spectra, several radiative properties for the prepared glasses. The calculated JO intensity parameters show the Ω4 > Ω6 > Ω2 trend which indicate rigid nature of the present glasses. The radiative transition probability, stimulated emission cross section and branching ratio show higher values for 4F3/2→4I11/2 transition. From properties evaluated in the present work it is concluded that the glass doped with 1.0 mol% Nd2O3 can be a potential candidate for laser applications.
关键词： Oscillator strengths,Branching ratio,Luminescent properties,JO theory
更新于2025-09-16 10:30:52
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Study of Electrophotophysical Characteristics of IR Photodetectors Based on PbS Colloidal Quantum Dots
摘要： The electrophotophysical characteristics of laboratory samples of IR photodetectors obtained by dip coating of PbS colloidal quantum dots with the subsequent exchange of oleic acid molecules that compose their ligand shell by S2? ions have been studied.
关键词： thin layers,electrophysical characteristics of layers,spectral and luminescent properties,dip-coating method,near infrared region,PbS colloidal quantum dots,ligand exchange,IR photodetectors
更新于2025-09-16 10:30:52
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A red-emitting phosphor K2[MoO2F4]?H2O:Mn4+ for warm white light-emitting diodes with a high color rendering index
摘要： A red-emitting phosphor K2[MoO2F4]?H2O:Mn4+ (denoted as KMOF:Mn4+) was designed and synthesized by a simple precipitation method, and its structure and luminescence properties were studied in details. The as-prepared KMOF:Mn4+ phosphors show broad excitation band in the blue-light region. The as-optimized phosphor KMOF:Mn4+ (3.28 mol%) has the strongest red-emission with high internal quantum efficiency of 86.5 % among these samples with different contents of Mn4+. Meanwhile, this sample is of the high thermal stability of luminescence. One white light-emitting diode (w-LED) was fabricated by coating KMOF:Mn4+ (3.28 mol%) and Y3Al5O12:Ce3+ on a GaN chip. This w-LED can emit intense warm white-light and show excellent photoelectric performances with a high color rendering index of 94, a low correlated color temperature of 3945 K, and the high luminous efficiency of 150.1 lm/W. Hence, KMOF:Mn4+ (3.28 mol%) could be a promising red phosphor for w-LEDs.
关键词： A. Optical materials,B. Fluorides,D. Phosphors,C. Luminescent properties
更新于2025-09-11 14:15:04
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Physical properties of fluorides barium and calcium nanopowders produced by the pulsed electron beam evaporation method
摘要： The mesoporous nanocrystal powders BaF2 and CaF2 with a specific surface up to 34.8 and 88.7 sq.m/g, respectively, are produced by the pulsed electron beam evaporation method in vacuum. The influence of thermal annealing of nanoparticles on air in the range of temperature from 200 to 900°C on the size, morphology of particles and change of their magnetic and luminescent properties investigated have been investigared. The essential stoichiometric impurity (overage of metals) and significant growth in a specific surface of nanopowders (NP) BaF2 and CaF2 after annealing at the temperature of 200°C have been detected. It is established that the synthesized NP BaF2 is a paramagnetic while initial material in the bulk state is diamagnetic. After annealing at 900°C appears the small ferromagnetic contribution at NP BaF2. Produced NP CaF2 showed ferromagnetic behavior. In literature there is no information about the ferromagnetism of CaF2. Appearance of the ferromagnetic response can be explained with formation of structural and radiation defects (F-centers, etc.). The analysis of PCL and magnetization curves of samples BaF2 and CaF2 allows drawing conclusions about their connection.
关键词： CaF2,pulsed electron beam evaporation,magnetic properties,luminescent properties,nanopowders,BaF2
更新于2025-09-10 09:29:36
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Synthesis, characterization, thermal and luminescent properties of thiophenol-functionalized platinum(II) bis(acetylide) complexes
摘要： Two thiophenol-functionalized trans-platinum(II) bis(acetylide) complexes, having one thiophenol moiety in each alkenyl backbone with general formula trans-[(PPh3)2Pt{C≡C–Ar–CH=CH(SC6H5)}2], (2a–2b), (Ar = phenylene or 2,5-dimethylphenylene), were synthesized in good yields and good regioselectivities. Compared to the absorption bands of the trans-platinum(II) bis(acetylide) complexes 1, the positions of the lowest energy absorption bands were redshifted by 17–18 nm, after functionalization with thiophenol. For both of the platinum(II) complexes 2, the lowest energy absorption bands in chloroform solution at room temperature were observed in the range 376–379 nm, and under excitation at the absorption maximum both complexes showed emission maxima in the range of 408–419 nm. All the new Pt complexes have been characterized by physico-chemical and spectroscopic methods.
关键词： thermal properties,thiophenol-functionalized,characterization,synthesis,platinum(II) bis(acetylide) complexes,luminescent properties
更新于2025-09-10 09:29:36
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Influence of the Tb3+ concentration on the luminescent properties of high silica glass
摘要： Tb3+- doped high silica glass was prepared by sintering porous glass. The density, valence state and amount of Tb, transmittance, photoexcitation spectra, photoluminescence spectra, and cathodoluminescence spectra (CL) were recorded and the luminescence decay kinetics analyzed in details. These results show that the doping concentration in high silica glass is in direct proportion to the concentration in solution, and the density increases with the increasing concentration of rare earth ions as well as the intensity of emission spectrum. The largest emission intensity of 0.2 mol/L is more than 2 times higher than the intensity of the 0.05 mol/L. Besides, the “red” shift phenomenon could be distinguished clearly in the transmittance spectra. There is a broad band at the “red” region in the CL spectra. The decay time which is in the millisecond range in di?erent spectral range were measured and analyzed revealing that the decay time of 5D3 is shorter than that of 5D4.
关键词： Luminescent properties,Rare earth ions,High silica porous glass
更新于2025-09-10 09:29:36