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Copper nanoparticles enhanced luminescence of Eu3+ doped lead tellurite glass ceramics
摘要： Structural, optical and magnetic properties of some lead tellurite glass ceramics doped with europium(III) ions and co-doped with fixed amounts of metallic copper nanoparticles (CuNPs) or copper(II) ions (via CuO) were investigated. Samples in the (Eu2O3)x·(TeO2)80·(PbO)(19.7-x)·(CuNPs)0.3 and (Eu2O3)x·(TeO2)80·(PbO)(19.7-x)·(CuO)0.3 systems with 0 ≤ x ≤ 10 mol% were obtained and investigated for the first time. Several techniques such as X-ray diffraction, UV-VIS, EPR and luminescence spectroscopies and density and magnetic susceptibility measurements were used in order to characterize the samples. XRD data show that the samples with low Eu2O3 contents (x ≤ 1 mol%) are amorphous while for higher europium oxide contents (x > 1 mol%) are glass ceramics. They also reveal that increasing the Eu2O3 content of samples the symmetry around the europium ions changes from face centered cubic to monoclinic. These symmetry changes are confirmed by the photoluminescence data. In addition, photoluminescence data show that the co-doping with metallic copper nanoparticles enhances the emission peaks of europium ions. UV-VIS absorption spectra show the presence of six coordinated copper (II) ions located at sites with a distorted octahedral symmetry. The EPR data confirm the presence of copper (II) ions in all the studied samples. Magnetic susceptibility measurements suggest the presence of europium ions in both their 3+ and 2+ valence states and evidence an important clustering tendency of europium ions even for low Eu2O3 contents.
关键词： EPR,UV-VIS,Photoluminescence,Magnetic susceptibility,Lead-tellurite glass ceramics,XRD
更新于2025-09-23 15:21:01
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Fluorescence resonance energy transfer (FRET) between acriflavine and CdTe quantum dot
摘要： In this report we have studied Fluorescence Resonance Energy Transfer between Acri?avine (Acf) and Cadmium Telluride (CdTe) quantum dot. CdTe quantum dots were synthesized by hydrothermal method. Spectroscopic characterizations revealed the formation of a FRET pair consisting of Acri?avine (AcF) as donor and CdTe quantum dot as acceptor having energy transfer ef?ciency 39.5%.
关键词： Quantum dot,XRD,CdTe,FRET
更新于2025-09-23 15:21:01
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Synthesis, DFT studies, fabrication, and optical characterization of the [ZnCMC] <sup>TF</sup> polymer (organic/inorganic) as an optoelectronic device
摘要： A novel carboxymethyl cellulose zinc thin film [ZnCMC]TF was fabricated using the sol–gel technique. Different characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and the optical properties were used to study the properties of [ZnCMC]TF. The molecular structure, FTIR, and optical properties were optimized. The Raman spectrum of the [ZnCMC]TF complex shows several bands in the range of 72–556 cm?1 due to (nZn–O) stretching and (Zn–O) bending, which is an obvious distinction between the FTIR and Raman spectra of [ZnCMC]TF. The optimization was performed using density functional theory (DFT) by DMol3 and Cambridge Serial Total Energy Package (CASTEP) program. The chemical structure was confirmed by spectroscopic and structural properties for both CMC and [ZnCMC]TF; the XRD results showed the same crystal structure (Monoclinic 2). [ZnCMC]TF has a larger grain size than CMC and has a similar behavior in the optical gap energy. The optical constants increased with increasing photon energy, refractive index n, absorption index k, and optical conductivity. The SEM images provide very good evidence in favor of the reaction of zinc transition metal with CMC for the formation of the [ZnCMC]TF complex. The resulting [CMC] spherical thin film and the [ZnCMC]TF polymeric nanorods were examined by different techniques including TEM and EDX. The optical properties obtained from the simulated FTIR, XRD, and CASTEP are in good agreement with those obtained from the experimental studies on CMC and ZnCMC. Based on the optical findings, [ZnCMC]TF is a promising candidate in applications such as solar cells and optoelectronic devices.
关键词： TEM,DMol3,zinc thin film,carboxymethyl cellulose,UV-Vis,DFT,optoelectronic devices,XRD,EDX,CASTEP,sol–gel technique,SEM,FTIR,optical properties,Raman spectroscopy
更新于2025-09-23 15:21:01
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Evolution of Size and Optical Properties of Upconverting Nanoparticles during High Temperature Synthesis
摘要： We investigated the growth of β-phase NaYF4:Yb3+,Er3+ upconversion nanoparticles synthesized by the thermal decomposition method using a combination of in situ and offline analytical methods for determining the application-relevant optical properties, size, crystal phase, and chemical composition. This included in situ steady state luminescence in combination with offline time-resolved luminescence spectroscopy, as well as small-angle X-ray scattering (SAXS) transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), and inductively coupled plasma optical emission spectrometry (ICP-OES). For assessing the suitability of our optical monitoring approach, the in situ collected spectroscopic data, that reveal the luminescence evolution during nanocrystal synthesis, were compared to measurements done after cooling of the reaction mixture of the as-synthesized particles. The excellent correlation of the in situ and time-resolved upconversion luminescence with the nanoparticle sizes determined during the course of the reaction provides important insights into the various stages of nanoparticle growth. This study highlights the capability of in situ luminescence monitoring to control the efficiency of UCNP synthesis, particularly the reaction times at elevated temperatures and the particle quality in terms of size, shape and crystall structure, as well as luminescence lifetime and upconversion quantum yield.
关键词： thermal decomposition,XRD,ICP-OES,TEM,in situ luminescence,SAXS,upconversion nanoparticles
更新于2025-09-23 15:21:01
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Crystallite size and microstrain: XRD line broadening analysis of AgSiN thin films
摘要： Purpose – This paper aims to determine the crystallite size and microstrain values of AgSiN thin films using potential approach called approximation method. This method can be used as a replacement for other determination methods such as Williamson-Hall (W-H) plot and Warren-Averbach analysis. Design/methodology/approach – The monolayer AgSiN thin films on Ti6Al4V alloy were fabricated using magnetron sputtering technique. To evaluate the crystallite size and microstrain values, the thin films were deposited under different bias voltage ((cid:1)75, (cid:1)150 and (cid:1)200 V). X-ray diffraction (XRD) broadening profile along with approximation method were used to determine the crystallite size and microstrain values. The reliability of the method was proved by comparing it with scanning electron microscopy graph and W-H plot method. The second parameters’ microstrain obtained was used to project the residual stress present in the thin films. Further discussion on the thin films was done by relating the residual stress with the adhesion strength and the thickness of the films. Findings – XRD-approximation method results revealed that the crystallite size values obtained from the method were in a good agreement when it is compared with Scherer formula and W-H method. Meanwhile, the calculations for thin films corresponding residual stresses were correlated well with scratch adhesion critical loads with the lowest residual stress was noted for sample with lowest microstrain and has thickest thickness among the three samples. Practical implications – The fabricated thin films were intended to be used in antibacterial applications. Originality/value – Up to the knowledge from literature review, there are no reports on depositing AgSiN on Ti6Al4V alloy via magnetron sputtering to elucidate the crystallite size and microstrain properties using the approximation method.
关键词： AgSiN thin films,XRD-approximation method,Microstrain,Crystallite size
更新于2025-09-23 15:21:01
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Structural and Quantitative Investigation of Perovskite Pore Filling in Mesoporous Metal Oxides
摘要： In recent years, hybrid organic–inorganic perovskite light absorbers have attracted much attention in the field of solar cells due to their optoelectronic characteristics that enable high power conversion efficiencies. Perovskite-based solar cells’ efficiency has increased dramatically from 3.8% to more than 20% in just a few years, making them a promising low-cost alternative for photovoltaic applications. The deposition of perovskite into a mesoporous metal oxide is an influential factor affecting solar cell performance. Full coverage and pore filling into the porous metal oxide are important issues in the fabrication of highly-efficient mesoporous perovskite solar cells. In this work, we carry out a structural and quantitative investigation of CH3NH3PbI3 pore filling deposited via sequential two-step deposition into two different mesoporous metal oxides—TiO2 and Al2O3. We avoid using a hole conductor in the perovskite solar cells studied in this work to eliminate undesirable end results. Filling oxide pores with perovskite was characterized by Energy Dispersive X-ray Spectroscopy (EDS) in Transmission Electron Microscopy (TEM) on cross-sectional focused ion beam (FIB) lamellae. Complete pore filling of CH3NH3PbI3 perovskite into the metal oxide pores was observed down to X-depth, showing the presence of Pb and I inside the pores. The observations reported in this work are particularly important for mesoporous Al2O3 perovskite solar cells, as pore filling is essential for the operation of this solar cell structure. This work presents structural and quantitative proof of complete pore filling into mesoporous perovskite-based solar cells, substantiating their high power conversion efficiency.
关键词： STEM-TEM,mesoporous,perovskite,pore filling,XRD
更新于2025-09-23 15:21:01
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Chemical effects during the formation of various types of femtosecond laser-generated surface structures on titanium alloy
摘要： In this contribution, chemical, structural, and mechanical alterations in various types of femtosecond laser-generated surface structures, i.e., laser-induced periodic surface structures (LIPSS, ripples), Grooves, and Spikes on titanium alloy, are characterized by various surface analytical techniques, including X-ray diffraction and glow-discharge optical emission spectroscopy. The formation of oxide layers of the different laser-based structures inherently influences the friction and wear performance as demonstrated in oil-lubricated reciprocating sliding tribological tests (RSTTs) along with subsequent elemental mapping by energy-dispersive X-ray analysis. It is revealed that the fs-laser scan processing (790 nm, 30 fs, 1 kHz) of near-wavelength-sized LIPSS leads to the formation of a graded oxide layer extending a few hundreds of nanometers into depth, consisting mainly of amorphous oxides. Other superficial fs-laser-generated structures such as periodic Grooves and irregular Spikes produced at higher fluences and effective number of pulses per unit area present even thicker graded oxide layers that are also suitable for friction reduction and wear resistance. Ultimately, these femtosecond laser-induced nanostructured surface layers efficiently prevent a direct metal-to-metal contact in the RSTT and may act as an anchor layer for specific wear-reducing additives contained in the used engine oil.
关键词： Tribology,Femtosecond laser processing,GD-OES,Surface chemistry,XRD,LIPSS,Laser-induced periodic surface structures,Laser-induced oxide layer
更新于2025-09-23 15:19:57
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Effect of laser shock peening on mechanical and microstructural aspects of 6061-T6 aluminum alloy
摘要： Laser shock peening (LSP) of 6061-T6 aluminum alloy was performed and parametric effects post LSP on mechanical aspects and microstructural evolution are meticulously studied using various means of characterization techniques such as residual stress analysis, surface roughness, Vickers microhardness, tensile testing, X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD). Work hardened layer of ~1500 μm depth is obtained with significant improvement in cross-sectional microhardness up to 33.04%. Beneficial compressive residual stress of maximum magnitude up to -273 MPa was induced in laser peened specimens concentrating its overall effect around the depth of 100 μm along the effective depth region. Second phase Mg5Si6 (β?) precipitates were observed post LSP while analyzing XRD profiles along with the peak broadening and peak shifting towards higher 2θ angle justifying the results obtained in microhardness profile. High angle grain boundaries (HAGBs) fraction was increased in LSPed specimens and its effect is noticed in residual stress profile. Mg5Si6 (β?) precipitates are attributed as contributing precipitates in improving the mechanical properties of LSPed specimens along with the dense dislocation density caused by severe plastic deformation during LSP. The collective contribution of strain hardening, second phase precipitates, peak broadening, dislocation density and increased fraction of HAGBs is observed in mechanical and microstructural aspects of LSPed specimens. The results are discussed in detailed and are strongly correlated with each other.
关键词： EBSD,Aluminum alloy,cosα method,TEM,XRD,Laser shock peening
更新于2025-09-23 15:19:57
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Novel approach to enhance light absorption of porphyrin/graphene oxide composites by PH and concentration modification for energy applications
摘要： Graphene oxide (GO) decorated with nanostructured porphyrin (PN) was synthesized and the interfacial interaction between these two components were investigated by using Scanning electron microscopy (SEM), X-ray, and UV-Visible absorption spectroscopy. These techniques showed good dispersion of GO and PN as well as a π-π intermolecular interaction confirming the energy/charge transfer. Moreover, X-ray diffraction study confirmed the intercalation of PN in GO and their disaggregation. The UV-Visible results showed an important interaction between GO and porphyrin nanorods under different pH values and concentrations resulting in the enhancement of optical absorption of GO-PN. The findings presented here are important to achieve the functionalization of graphene oxide with PN for various optoelectronic applications.
关键词： UV-Visible absorption,Porphyrin,Graphene,XRD,SEM
更新于2025-09-23 15:19:57
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Spectroscopic and laser properties of erbium and ytterbium co-doped photo-thermo-refractive glass
摘要： Spectral-luminescent characteristics of erbium ions in photo-thermo-refractive (PTR) glasses doped with different concentrations of ytterbium and erbium oxides were investigated in this work. X-ray diffraction pattern of studied glasses was carried out. Judd-Ofelt parameters of intensity Ωt were obtained and used for deriving emission cross-sections and radiative lifetimes. It was found that the peak emission cross-sections values at a wavelength of 1.53 μm obtained from F-L and McCumber methods are 0.59 × 10?20 cm2 and 0.60 × 10?20 cm2, respectively, which are very similar and compared with those of silicate glasses. A quite high value of quantum yield at the wavelength of 1.53 μm for the sample with 0.1 mol% Er2O3 co-doped with ytterbium oxide has been investigated. Energy transfer efficiency from ytterbium ions to erbium ones was found to be 80% and 86% for erbium- and 1 mol% and 2 mol% Yb2O3-co-doped PTR glass, respectively. Laser properties of 2Yb-01Er PTR glass were carried out. The gain spectrum starts to be positive when the population inversion parameter gets to 0.5. Laser action was demonstrated at room temperature. It was found that the round-trip losses of the Er/Yb-PTR element are 0.28%.
关键词： Ytterbium,DFB laser,PTR glass,Erbium,XRD,Judd-ofelt
更新于2025-09-23 15:19:57