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Mode-locked near-infrared thulium doped fibre laser using evanescent field effect with Bi <sub/>2</sub> O <sub/>3</sub> saturable absorber
摘要： Using the evanescent field effect, a high power passively mode-locked laser with a pulse duration of 1.85 ps and the pulse energy of 13.15 pJ is demonstrated. A Bi2O3 solution is used as a saturable absorber (SA) on a side polished fibre incorporated into a thulium doped fibre laser cavity for operation in the mid-infrared range. The 37.61% SA has a modulation depth and creates a highly stable mode-locked pulse output with a short pulse duration. The calculated net cavity dispersion at central wavelength is ?1.4 ps2, indicating operation is in the anomalous dispersion regime and confirmed by the presence of Kelly’s side-bands observed in the generated optical spectrum. Radio frequency analysis reveals a high signal to noise ratio, making this laser stable for use in telecommunication systems.
关键词： thulium doped fibre laser,evanescent field effect,Bi2O3 saturable absorber
更新于2025-11-28 14:23:57
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Effects of Ge substrate on the structural and optical conductivity parameters of Bi2O3 thin films
摘要： In this article the structural, optical and dielectric properties of a 200 nm thick Bi2O3 thin films which are deposited onto amorphous germanium substrate are reported. Both of the Ge and Bi2O3 thin films are prepared by the thermal evaporation technique under vacuum pressure of 10^-5 mbar. Bi2O3 thin films are found to prefer the monoclinic nature of structure with larger values of microstrain, dislocation density, stacking faults and smaller grain sizes upon replacement of the glass substrate by germanium. Optically, significant redshift in the energy band gap is observed when the films are grown onto Ge. The Ge/Bi2O3 heterojunctions exhibit a conduction and valence band offsets of value of 0.81 and 1.38 eV, respectively. In addition to the enhancement in the dielectric constant near the IR region, the Drude-Lorentz modeling of the Ge/Bi2O3 heterojunctions has shown remarkable effect of the Ge substrate on the optical conductivity parameters of Bi2O3. Particularly, the drift mobility increased by about one order of magnitude, the free hole density decreased by ~24 times and the plasmon frequency ranges extended from 5.21 to 11.0 GHz to 2.59–12.80 GHz when germanium substrate is used. The optical features of the heterojunction nominate it for visible light communication technology.
关键词： Ge/Bi2O3,Band offsets,X-ray,Heterojunction,Plasmon,Dielectric
更新于2025-09-23 15:23:52
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α-NiS/Bi <sub/>2</sub> O <sub/>3</sub> Nanocomposites for Enhanced Photocatalytic Degradation of Tramadol
摘要： In this study, a series of α-NiS/Bi2O3 composite nanomaterials were prepared and evaluated as efficient photocatalyst for degradation of tramadol under visible light. Two polymorphs of Bi2O3 namely α- (monoclinic) and β- (tetragonal) were prepared by using combustion method and bismuth subcarbonate decomposition route, respectively. A facile method was also developed for synthesis of ultrathin α-NiS nanosheets under mild conditions using hexamethylenetetramine as hydrolyzing agent and Na2S2O3 as sulfur source. The NiS/α-Bi2O3 and NiS/β-Bi2O3 composite materials were thoroughly characterized using a variety of techniques to understand their structural, optical, electrochemical, microstructural and morphological attributes. The α-NiS/Bi2O3 materials exhibited improved visible light absorption, enhanced charge carrier separation and photo-electrochemical properties. The microscopic close contact between the two semiconductor phases is established from the morphological studies. The α-NiS/Bi2O3 materials exhibited excellent photocatalytic activity for aqueous phase degradation of tramadol under visible light irradiation. Particularly, the α-NiS/β-Bi2O3 system is highly active achieving 94% degradation in 3 h. The mechanism of photocatalytic action involves a z-scheme electron transfer from the CB of Bi2O3 to the VB of NiS which is responsible for efficient space separation of charge carriers and their increased reactivity. The ?OH radicals and h+ species have been identified as the major transient species responsible for tramadol oxidation. The photocatalytic method developed in this study can be a viable alternative for TiO2 based UV active photocatalyst studied so far for tramadol degradation.
关键词： Tramadol,Bi2O3,Photocatalysis,α-NiS,Z-scheme
更新于2025-09-23 15:23:52
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Preparation of 3D flower-like Fe-Bi2O3 nanocomposite and its photocatalytic performance under visible light irradiation
摘要： The objective followed by this research is the synthesis of 3D ?ower-like Fe-Bi2O3 and the study of its capability for the degradation of Rhodamine B (RhB) under visible light irradiation (λ > 400 nm). Samples were obtained by a simple sol–gel method at room temperature. The as-prepared Fe-Bi2O3 exhibited excellent photocatalytic performance under the visible light due to its relatively narrow band gap energy (2.83 eV). The photocatalytic activity was carefully evaluated with respect to RhB photodegradation in di?erent conditions such as light source and reaction time. The experimental results showed that the degradation rate of 3D ?ower-like Fe-Bi2O3 is up to 82% under visible light irradiation, when EtOH/H2O volume ratio and Bi/Fe molar ratio are 7:3 and 20:1, respectively.
关键词： Nanocomposites,Fe-Bi2O3,Sol-gel,Photocatalytic activity
更新于2025-09-23 15:23:52
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Enhancement of luminescence intensity and spectroscopic analysis of Eu3+ activated and Li+ charge-compensated Bi2O3 nanophosphors for solid-state lighting
摘要： The present work reports the synthesis, characterization, photoluminescence and photocatalytic activity of Eu3+ (1-11 mol %) doped and Li+ (0.5-5 mol %) co-doped Bi2O3 nanophosphors (NPs) by sonochemical method. The average particle size was estimated using powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM) and found to be in the range of 30 to 35 nm. The scanning electron microscopy (SEM) images were highly dependent on sonication time and concentration of Epigallocatechin gallate (EGCG) bio-surfactant. The energy gap of doped and co-doped Bi2O3 nanophosphors was estimated using Kubelka-Munk (K-M) function and found to be in the range 2.9-3.08 eV. The effect of Li+ co-doping on luminescence of optimized Bi2O3:Eu3+ was studied and found about more than 3 fold enhancement of emission intensity. Judd–Ofelt parameters (Ω2, Ω4 and Ω6), transition probabilities (AT), quantum efficiency (η), luminescence lifetime (τrad), color chromaticity coordinates (CIE) and correlated color temperature (CCT) values were estimated from the emission spectra and discussed in detail. The estimated CIE chromaticity co-ordinates were very close to the NTSC (National Television Standard Committee) standard value of red emission. The synthesized NPs show excellent photocatalytic activity of Acid red-88 under UV-light irradiation, which can degrade 98.1 % in 60 min. The decreasing electron-hole pair recombination rate with quick electron transfer ability was predominantly ascribed to the balance between crystallite size, morphology, band gap, defects, surface area etc. These results through a light for the use of sonochemical route of Bi2O3:Eu3+:Li+ in solid state display and photocatalytic applications.
关键词： Photoluminescence,Sonochemical,Bi2O3:Eu3+:Li+,Photocatalysis,CIE n CCT
更新于2025-09-23 15:21:21
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Bismuth oxide modified europium and niobium co-doped titanium dioxide ceramics: Colossal permittivity and low dielectric loss design
摘要： Colossal permittivity (CP) materials have many important applications in electronics but their development is generally hindered due to the difficulty in achieving a relatively low dielectric loss. In this work, based on the electron-pinned defect-dipole and internal barrier layer capacitance (IBLC) theory, we designed to add Bi2O3 to (Eu0.5Nb0.5)0.01Ti0.9O2 (ENTO) ceramics to obtain high performance CP materials. The dielectric loss can be reduced down to 0.017 at 1 kHz and room temperature, while the permittivity is kept at a relatively high value (2.7×104). At the same time, the temperature and frequency stability can also be improved. More importantly, the mechanism of decreasing dielectric loss is studied. It is finding that the decrease of dielectric loss is closely associated with the enhanced localized behavior of conduction process at grain boundary. The addition of Bi2O3 can increase the grain boundary resistance and grain-boundary activation energy of the ceramics, which make the conductive behavior of the grain boundaries more difficult, resulting in decreasing the dielectric loss and improve the temperature stability of the ceramics.
关键词： Electronic localization,Bi2O3 modified,Low dielectric loss,TiO2 ceramics
更新于2025-09-23 15:21:01
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Structural and optical properties of Gd+3 doped Bi2O3-GeO2 glasses and glass-ceramics
摘要： The gadolinium doped Bi2O3-GeO2 glasses and glass-ceramics have been synthesized by melt quenching and heat treatment. Structural and optical properties of prepared glasses and glass-ceramics have been examined by X-ray diffraction (XRD), Fourier transform infrared, absorption and emission measurements. XRD results have shown that the precipitated crystalline phases in glass-ceramics samples are Bi2GeO5, Bi2Ge3O9 and Bi4Ge3O12. [BiO3] and [GeO4] units are the main structural units present in Bi2O3-GeO2 glass and glass-ceramic network confirmed by IR spectra. Optical band gap values of prepared glass and glass-ceramic systems obtained from absorption spectra vary from 2.01 to 3.34 eV. The optical band gap values of glasses are larger than glass-ceramics. Bi2O3-GeO2 glass-ceramics have higher density values than glasses and densities present an increase with the elevated Gd3+ content. It is suggested that the luminescence under 366 nm excitation has been ascribed to different Bi-related emission centers. The CIE color coordinates and CCT values obtained under 366 nm excitation confirm that the Gd3+ doped bismuth germanate glasses and glass-ceramics exhibit white light emission. The most promising material for white light emitting applications within our research is found to be GC-2Gd with coordinates of (0.327, 0.314) and a CCT of 5753 K.
关键词： glass,bismuth,glass-ceramic,Gadolinium,white light,Bi2O3-GeO2
更新于2025-09-23 15:21:01
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Degradación Fotocatalítica de Contaminantes Orgánicos Presentes en Agua Residual de la Industria Litográfica mediante Oxido de Bismuto(NI)/Oxido de Titanio (Bi2O3/TiO2)
摘要： Se prepararon semiconductores acoplados de Bi2O3/TiO2 mediante el método de impregnación húmeda. La actividad fotocatalítica se evaluó sobre la degradación de compuestos orgánicos presentes en agua residual generada por la industria litográfica bajo irradiación UV-visible y fueron caracterizados mediante difracción de rayos x, espectroscopia UV visible e infrarroja. Se utilizó la metodología de superficie de respuesta a través de un dise?o factorial de tres niveles para evaluar el efecto combinado de la relación Bi2O3/TiO2 y el pH inicial de la solución. Las respuestas evaluadas fueron los porcentajes de remoción de carbono orgánico total y Demanda Química de Oxígeno. Los resultados revelaron que los materiales compuestos (composites) de Bi2O3/TiO2 mostraron un menor tama?o de cristal, mayor estabilidad térmica y una mayor absorción en el rango visible que el TiO2 puro.
关键词： degradación fotocatalítica,agua residual,industria litográfica,Bi2O3/TiO2,superficie de respuesta
更新于2025-09-23 15:21:01
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Orientation factor and piezoelectric property in textured (K,Na)NbO <sub/>3</sub> system ceramics with minimal templates
摘要： To lower the sintering temperature and decrease the weight ratio of templates required for fabricating textured (K,Na)NbO3 (KNN) system ceramics, the method of preparing platelike NaNbO3 (NN) single-crystal particles for the templates was improved. The NN crystal particles synthesized by the single-step molten salt method using a mixed salt were treated by ultrasonic vibration and subsequently screened. Using these improved templates, we developed the fabrication method for the textured KNN system ceramics by which the weight ratio of the templates required for the orientation control can be reduced to 1/10 of the conventional weight ratio. The effects of decreasing the weight ratio of templates on sintering temperature, orientation factor, and piezoelectric properties were investigated. In addition, the effects of adding Bi2O3 to KNN calcined powder were also studied to suppress abnormal grain growth, which appears in the textured samples fabricated using smaller amounts of the templates.
关键词： reactive template grain growth,molten salt synthesis,Bi2O3 addition,lead-free piezoelectric materials,ultrasonic treatment,textured ceramics
更新于2025-09-23 15:21:01
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Controlled synthesis and upconversion luminescence properties of Yb3+/Er3+ co-doped Bi2O3 nanospheres for optical and X-ray computed tomography imaging
摘要： Bi2O3 nanospheres co-doped with Yb3t/Er3t upconverting ions pair have been successfully synthesized via a facile hydrothermal method followed by a heat treatment. The resulting Bi2O3:Yb3t,Er3t nanospheres show a monodisperse spherical morphology with narrow size distribution (~180 nm) and display intense upconversion luminescence under 980 nm laser excitation. It is found that the crystal structure, morphology and upconversion luminescence properties of nanospheres have a direct relationship with the doping concentration of Yb3t and the subsequent calcination temperature. These Bi2O3:Yb3t,Er3t nanospheres can be prepared in large quantities and can be easily modified with a layer of biocompatible polyethyleneimine (PEI) molecules. The yielded nanospheres could not only maintain uniform size and morphological characteristics, but also show good water dispersibility and biocompatibility. Remarkably, these Bi2O3:Yb3t,Er3t upconversion nanophosphors could also act as an effective contrast agent for X-ray computed tomography (CT) imaging, which show higher contrast efficacy than commercial iodine-based contrast agent. The proposed facile synthetic route and inexpensive matrix materials pave the way for broad use of these Bi2O3:Yb3t,Er3t nanospheres as ideal dual-mode bio-imaging probes in biomedical field.
关键词： Hydrothermal synthesis,CT imaging,Bi2O3,Upconversion luminescence,Nanophosphors
更新于2025-09-23 15:19:57