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Characteristics of the Structural State of Bismuth Ions in Bismuth-Borate Glasses
摘要： The properties and graphical plots of the properties of bismuth-borate glasses in a wide range of compositions — 20 to 80 mol.% Bi2O3 — are presented. In multi-bismuth glasses both the boron and bismuth ions are found in two coordination states: B3+, B4+ and Bi3+, Bi6+. The [BiO3] groups play the role of a conventional glass former but manifest weakly in the IR spectra.
关键词： structure of bismuth-borate glasses,properties of bismuth-borate glasses,lead-free low-melting glasses,structural role of Bi ions
更新于2025-09-19 17:15:36
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C-doping into h-BN at low annealing temperature by alkaline earth metal borate for photoredox activity
摘要： BCN (boron carbon nitride) nanosheets are promising photocatalyst materials for solar fuel production by visible light-driven water splitting and CO2 reduction due to their tunable band gap and unique properties. C-doping into h-BN by thermal annealing makes possible the preparation of BCN nanosheets with photocatalytic activity under visible light irradiation, but it generally requires a very high temperature (>1250 °C) from the thermodynamic viewpoint. Here, we report a new method to prepare BCN nanosheets with visible light-photocatalytic activity at lower annealing temperature (1000 °C) than equilibrium by adding alkaline earth metal compounds. BCN nanosheets formed in borate melt show a clear layered structure, tunable bandgap and photocatalytic activity for water splitting and CO2 reduction under visible light illumination. This provides a direction for doping other elements into h-BN at low annealing temperature by alkaline earth metal borates.
关键词： h-BN,low annealing temperature,BCN nanosheets,water splitting,CO2 reduction,C-doping,photoredox activity,alkaline earth metal borate
更新于2025-09-19 17:15:36
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Stabilization of GaAs photoanodes by in-situ deposition of nickel-borate surface catalyst as hole trapping sites
摘要： Although semiconducting gallium arsenide (GaAs) possesses an ideal band gap for efficient solar-driven fuel synthesis, it is extremely unstable in aqueous media, undergoing facile photocorrosion and therefore is seldom used. We have addressed this stability problem to some extent using a strategy of introducing a Ni-B surface catalyst onto p/n junction GaAs by in-situ photoassisted electrodeposition. A monolithic layer of Ni-B/Ga(As)Ox was generated during the Ni-B deposition process, resulting in a Ni-B/Ga(As)Ox/GaAs photoanode structure. Such structure was optimized by varying the GaAs surface architecture, electrolyte pH value and Ni-B deposition time to achieve optimal photoelectrochemical performance, together with improved stability. The optimized photoanode (Ni-B/Ga(As)Ox/shallow GaAs with 0.5 h Ni-B deposition time (~ 900 nm thickness of Ni-B/Ga(As)Ox layer) exhibited a very high photocurrent, leading to a nearly 22 hour stable photocurrent density of 20 mA/cm2, while the bare GaAs represents 60 % photocurrent loss after three hours under continuous one sun illumination (100 mW/cm2) in an alkaline media (pH=14). This remarkable performance in both photocurrent and stability directly address the current severe limitations in the application of GaAs photoanodes for solar fuel synthesis, and maybe applicable to other unstable photoelectrodes.
关键词： Nickel borate,Photoanode stabilization,Gallium arsenide,Solar energy conversion
更新于2025-09-19 17:15:36
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Studies on pelletized lithium magnesium borate TL material for eye lens dosimetry
摘要： Recent epidemiological studies in various cohorts confirm that radiation induced cataract may occur at a threshold dose as low as 0.5 Gy. ICRP has recognized the higher radiosensitivity of eye lens and recommended to reduce annual eye lens dose limit from 150 mSv to 20 mSv. Present dosimetry for eye lens is largely based on LiF based dosimeters. The present work is an attempt towards using near tissue equivalent lithium borate material namely lithium magnesium borate doped with terbium (LMB:Tb) in eye lens dosimetry. The material in powder form was synthesized using solid state sintering method and pelletized using poly tetra fluoro ethylene (PTFE) as binding agent. It was observed that 130 mg of 1mm thick LMB:Tb pellet bound with PTFE showed stable glow curve structure and attractive dosimetric features in terms of sensitivity, fading, linearity, reusability etc. A proposal of 1.5 mm Teflon encapsulation corresponding to tissue equivalent thickness of 3 mm was put forward for an ideal dosimeter for the measurement in terms of Hp(3). Energy and angular dependence studies based on FLUKA simulations suggest a flat response for the prototype design. In addition to PTFE, various tissue equivalent encapsulations such as polyimide, polyamide 6 and PMMA were also evaluated using FLUKA code.
关键词： thermoluminescence,Eye lens dosimetry,lithium borate phosphor
更新于2025-09-19 17:15:36
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Effect of co-doping of lithium on the dosimetric properties of dysprosium-doped sodium borate glass system
摘要： The effect of lithium (Li) as a co-dopant on the Thermoluminescence (TL) properties of dysprosium-doped sodium borate (NB: Dy) exposed to two radiation sources (linear accelerator and Gamma-ray from Co-60) is reported in this study. The results showed an enhancement in the TL intensity with the increment of lithium to NB: Dy. Promising dosimetric properties were recorded; glow curve with simple and prominent peak, high signal stability and simple annealing process. Furthermore, the phosphor is reusable and high dose linearity range (up to 103 Gy). The current results propose the using of the new dosimeter in different dosimetric applications.
关键词： Borate glass,Dysprosium oxide,Dosimeter
更新于2025-09-19 17:15:36
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Two- step synthesis and luminescent properties of BaB <sub/>2</sub> O <sub/>4</sub> :Eu <sup>3+</sup> nano/microphosphors prepared from Ba-B-O:Eu <sup>3+</sup> precursor
摘要： The BaB2O4:Eu3+ nano/microphosphors with sphere‐, rod‐, and granular‐like morphologies were successfully obtained by a two‐step method using Ba‐B‐O:Eu3+ as the precursor. The structure, morphology and photoluminescent properties of the products were characterized by Fourier transfer infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermogravimetry‐differential thermal analysis (TG‐DTA), scanning electron microscopy (SEM) and photoluminescence (PL). The formation mechanisms of Ba‐B‐O:Eu3+ and BaB2O4:Eu3+ were proposed. The results show that the BaB2O4:Eu3+ could retain the original morphologies of their respective precursors largely. The BaB2O4:Eu3+ prepared by this two‐step method exhibited better morphology, smaller particle size and better crystallinity than when prepared by a solid‐state method. The granular‐like BaB2O4:Eu3+ red phosphor prepared by this two‐step method exhibited stronger PL intensity and better red color purity than when prepared by a solid‐state method.
关键词： luminescence,nanophosphor,two‐step method,barium borate
更新于2025-09-19 17:15:36
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Rich reddish-orange emitting PBTNAPr glasses for laser applications
摘要： Lead borate oxyfluoride glasses containing different amounts of PrF3 with composition PbO–B2O3–TeO2–NaF–AlF3-PrF3 were prepared and characterized for visible and fiber lasers. The amorphous phase and compositional analysis were carried out through powder X-ray diffraction and Fourier transform infrared spectra, respectively. Using the room temperature optical absorption spectra, the spectroscopic properties were determined applying the modified Judd-Ofelt theory. The photoluminescence excitation spectral studies obtained by controlling the emission through Pr3+: 1D2 → 3H4 (604 nm) transition shows prominent excitation band positioned at ~448 nm (3H4 → 3P2). Upon 448 nm excitation, the studied glasses exhibit an intense emission through 1D2 → 3H4 (604 nm) transition along with feeble emissions from 3P1 and 3P0 metastable levels to the inner energy levels. The emission spectra show a shift towards longer wavelengths (called the red-shift) with increase of PrF3 content. The luminescence decay time of 1D2 emission level was found decreased with increase of PrF3 content. The quenching of decay time was assigned to the transfer of energy among the excited Pr3+ ions at relatively higher PrF3 contents. The experimental results show that the studied glasses with 0.1 mol% of PrF3 could be the suitable candidate to design rich reddish-orange emitting lasers.
关键词： Solid state lasers,Photoluminescence,Judd-Ofelt analysis,Lead borate glasses
更新于2025-09-19 17:13:59
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Comparative impact of Nd3+ ion doping concentration on near-infrared laser emission in lead borate glassy materials
摘要： Different concentrations (0.2-1.0 mol%) of Nd3+ doped lead borate glass (LB) systems were prepared by melt quenching technique and have been studied using XRD and optical studies. Based on the calculations of Judd-Ofelt (J-O) theory derived from the optical absorption spectra, three J-O parameters have been obtained. Various radiative parameters (such as radiative transition probability (Arad), branching ratio (βcal), absorption cross-sections (Σ), radiative lifetime (τR) and etc., have been predicted through J-O parameters. Luminescence spectra were measured for all the samples. It has been observed that luminesce intensity gradually increased up to 0.8 mol % of Nd3+ and further increase in concentrations causes that the luminescence spectral intensity falls. This is proposed due to the concentration quenching of neodymium ions in the LB glass system. LB glass system with 0.8 mol % is found to be most intensive one in emission at 1.06 μm related to 4F3/2→4I11/2 in near infrared (NIR) transition.
关键词： Absorption,emission cross-section,Photoluminescence,Judd-Ofelt,Lead borate glasses
更新于2025-09-19 17:13:59
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Temperature-Dependent Luminescence of Red-Emitting Ba2Y5B5O17: Eu3+ Phosphors with Efficiencies Close to Unity for Near-UV LEDs
摘要： Solid state white light sources based on a near-UV LED chip are gaining more and more attention. This is due to the increasing e?ciency of near-UV-emitting LED chips and wider phosphors selection if compared to devices based on blue LED chips. Here, a brief overview is given of the concepts of generating white light employing near-UV LED and some optical properties of the available phosphors are discussed. Finally, the synthesis and optical properties of very e?cient red-emitting Ba2Y5B5O17:Eu3+ phosphor powder and ceramics is reported and discussed in terms of possible application as a red component in near-UV LED-based white light sources.
关键词： Eu3+,ceramics,near-UV LED,quantum e?ciency,luminous e?cacy,red phosphor,borate,CIE 1931 colour coordinates,thermal quenching
更新于2025-09-19 17:13:59
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Luminescence study and Judd-Ofelt analysis of Nd 3+ doped lithium lanthanum borate glass for green laser device
摘要： Lithium lanthanum borated glasses doped with Nd3+ (LiLaBNd) were synthesized to study in luminescence properties and laser potential. Refractive index, density and molar volume of glass increase with increasing of Nd3+ concentration. Glasses absorb photon in visible light and near- infrared region corresponding to energy transition from 4I9/2 ground state of Nd3+. Covalent nature and interaction between Nd3+ and ligand result to small red shift of Nd3+ energy level. The strongest emission with 1059 nm corresponds to 4F3/2→4I11/2 transition of Nd3+ under 808 nm excitation. The optimum concentration of Nd2O3 for this glass is 0.50 mol% which creates the maximum intensity of emission. Luminescence decay curve indicated cross relaxation process between Nd3+with low probability and life time value as 114 microsecond for 0.50 mol% doped glass. Judd-Ofelt analysis was used to evaluate several radiative parameters. Narrow effective bandwidth, high stimulated emission cross section and branching ratio indicated the advantage potential to develop LiLaBNd glass for using as laser medium in green emitting laser device.
关键词： Luminescence,Borate glass,Neodymium
更新于2025-09-16 10:30:52