- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Harmonic mode-locking in an external cavity tapered diode laser with saw-toothed microstructure
摘要： As a widely used approach to modify a material’s bulk properties, doping can effectively improve electrochemical properties and structural stability of various cathodes for rechargeable batteries, which usually empirically favors a uniform distribution of dopants. It is reported that dopant aggregation effectively boosts the cyclability of a Mg-doped P2-type layered cathode (Na0.67Ni0.33Mn0.67O2). Experimental characterization and calculation consistently reveal that randomly distributed Mg dopants tend to segregate into the Na-layer during high-voltage cycling, leading to the formation of high-density precipitates. Intriguingly, such Mg-enriched precipitates, acting as 3D network pillars, can further enhance a material’s mechanical strength, suppress cracking, and consequently benefit cyclability. This work not only deepens the understanding on dopant evolution but also offers a conceptually new approach by utilizing precipitation strengthening design to counter cracking related degradation and improve high-voltage cyclability of layered cathodes.
关键词： doping,precipitation strengthening,TEM,layered cathodes
更新于2025-09-11 14:15:04
-
Stress Evolution during Ge Nanoparticles Growth in a SiO <sub/>2</sub> Matrix
摘要： Superstructures are explored that were obtained by multilayer magnetron deposition at room temperature of 20 SiO2 and SiO2:Ge bilayers, each 2 × 4 nm thick, and subsequently annealed in inert N2 atmosphere at different temperatures in the range of 500?750 °C. The structural and optical changes induced by annealing and the formation and growth of Ge nanoparticles (nps) from early clusters to their full growth and final dissolution were studied by the simultaneous grazing-incidence small- and wide-angle X-ray scattering, transmission electron microscopy, and (time-resolved) photoluminescence (PL). It is shown that in as-deposited multilayers aggregation of small clusters already occurred, and the clusters were reasonably well intercorrelated in the lateral plane. During annealing at Ta = 550 °C or higher temperatures, Ge nps start to form and remain partly amorphous at lower Ta but crystallize completely at about 600 °C. At even higher temperatures, the Ge nps dissolve and Ge diffuses out almost completely, leaving voids in the SiO2 matrix. Visible PL from the samples was detected and attributed to defects in the nps/matrix interface layers rather than to the nps itself because PL persisted even after Ge nps dissolution.
关键词： GIWAXS,photoluminescence,Ge nanoparticles,GISAXS,stress evolution,SiO2 matrix,TEM
更新于2025-09-11 14:15:04
-
[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu, China (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Analysis of TEM Horn with Dielectric Loaded
摘要： The radiation fields of transverse electromagnetic (TEM) horn as a nuclear electromagnetic pulse(NEMP) radiating-wave simulator are simulated by finite-difference time-domain(FDTD) method. The EMP’s effects of different dielectric load are numerical studied and analyzed. The results show that comparing with the traditional TEM horn antenna the peak value of Ez increases or decreases, but the FWHM never widen as TEM horn loaded by dielectric.
关键词： FDTD,Dielectric,Load,NEMP,TEM horn
更新于2025-09-10 09:29:36
-
European Microscopy Congress 2016: Proceedings || Exciton and Plasmon Mapping at the Nanoscale
摘要： Excitons and plasmonic interactions, which are effectively responsible for the transfer of energy within devices such as solar cells, LEDs and semiconductor circuits, have been understood in theory for decades. However, the photophysical behaviour within materials has always been rather difficult to understand and be directly observed. Surface structure, localised thickness variations and presence of edges are bound to influence the macroscopic properties of the materials. Understanding the local surface structure and chemistry of these materials at the nanoscale is crucial in order to reach the full potential of the materials for real-life applications. Hence, there is a need to fully characterise the physical and chemical properties from the bottom up i.e. at the level of individual atoms and to map the optoelectronic properties where they happen. Due to recent technical improvements we can now access parts of the low loss electron energy-loss (LL EEL) spectra which had previously been inaccessible. This opens up new possibilities to study nanomaterials not only at unprecedented energy but also – contrary to bulk optical techniques – with a spatial resolution at the nanoscale, as described by Zhou, Dellby [1]. Although some significant progress has been made recently in unravelling the physical origins of the LL EEL features as shown by Tizei, Lin [2], significant gaps in our understanding of the signals and their origins remain. In the study presented here, we used for the first time a combination of experimental monochromated LL STEM EEL spectroscopy and theoretical calculations using time-dependent density functional theory (TDDFT) as well as the Bethe-Salpeter equation (BSE) to study the optical properties of MoS2 at the nanoscale with the aim to understand the origins of the peaks and regional variations of the complete LL EEL spectrum. We report that we identified and resolved as well as mapped mid-bandgap excitonic signals at ~1.88eV and at ~2.08eV on MoS2 flakes using monochromated LL EELS (figure 1) and confirmed their origin by BSE calculations; we also identified and mapped several plasmonic peaks (figure 1) using LL EELS combined with TD DFT. Furthermore, we observed great spatial variations in the LL EELS signal when comparing the edge to inner regions of a flake, i.e. with increasing number of layers, and we show how these can be largely attributed to beam geometry effects. The effects of the experimental set-up on the low loss EELS signal will be discussed.
关键词： STEM,2D materials,MoS2,TEM,spectroscopy,Low loss EELS
更新于2025-09-10 09:29:36
-
[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Generating Electric Fields for Air Sensitivity Measurement of Specific Absorption Rate Probe
摘要： To measure the air sensitivity of a specific absorption rate (SAR) probe, an electric field (E-field) generation system is implemented using field-generating cells, a transverse electromagnetic (TEM) cell below 1 GHz and waveguides in 1.12–2.6 GHz-frequency range. The output side of the field-generating cells is terminated with an attenuator and a power sensor to determine the E-field strength which is traceable to power and attenuation standards. Measured results with the estimated uncertainty are presented at 835 MHz and 1800 MHz.
关键词： waveguide,uncertainty,Electric field,specific absorption rate,measurement standards,TEM cell
更新于2025-09-10 09:29:36
-
Molecular dynamics simulation and experimental verification for bonding formation of solid-state TiO2 nano-particles induced by high velocity collision
摘要： Collision processes of solid-state nano-sized ceramic particles were investigated by molecular dynamics (MD) simulation in order to clarify their bonding mechanisms. Effect of particle temperature on particle bonding formation was examined, and collision behavior of nano-sized TiO2 particle was discussed in terms of particle deformations. Microstructures and bonding qualities of bonded nano-sized TiO2 particles induced by high velocity collision were examined by high resolution transmission electron microscope (HR-TEM) to verify the MD results. Simulation results demonstrate that the bonding formation of nano-sized TiO2 particles can be attributed to the atomic displacement and lattice distortion in localized impact region of particle boundaries. TEM microstructure results prove simulation results and indicate effective chemical bonding formations between nano-particles at low temperature by high velocity collision. Quantitative results show that the high temperature is beneficial to the particle bonding formation. The asperity around nano-sized ceramic particles surface contributes to the displacement and lattice distortion in localized impact region under the high impact compressive pressure. The fact demonstrates a new mechanism of nano-scale ceramic particle bonding formation induced by the localized atomic displacement. The study present opens up a promising prospect of fabricating functional equipment with nano-scale ceramic particles with high velocity collision at ambient temperature.
关键词： Atomic displacement,MD simulation,Nano-ceramic particle,HR-TEM,Chemical bonding
更新于2025-09-10 09:29:36
-
Determination of Sulfite in Botanical Medicine Using Headspace Thin-Film Microextraction and Surface Enhanced Raman Spectrometry
摘要： A facile method using headspace thin-film microextraction (HS-TFME) coupled with surface enhanced Raman spectrometry (SERS) has been developed for the determination of sulfite in traditional Chinese herbal medicine. The extraction substrate was synthesized by depositing urchin-like ZnO micron particles on glass sheets using chemical liquid phase deposition. Under the optimal conditions, the intensity of the SERS signal at 630–640 cm?1 provided a good linear relationship with the concentration of sulfite from 25 to 400 mg/kg, and the linear correlation coefficient (R) was 0.996 with a detection limit of 6 mg/kg. The method was employed for the determination of sulfite in herbal medicines, and the results were confirmed by a traditional distillation-titration method. Therefore, this developed HS-TFME-SERS method may play an important role in the rapid, simple, and selective determination of sulfite residues in Chinese herbal medicine and become a potentially universal method for this analyte in various solid samples.
关键词： Headspace thin-film microextraction (HS-TFME),scanning electron microscopy (SEM),X-ray diffraction (XRD),surface enhanced Raman spectrometry (SERS),transmission electron microscopy (TEM)
更新于2025-09-10 09:29:36
-
Preparation and characterization of graphene – TiO2 nanocomposite for enhanced photodegradation of Rhodamine-B dye
摘要： The synthesizing of TiO2@rGO nanocomposites using an efficient method has been carried out to enhance the photodegradation activities of TiO2. Reduced graphene oxide (rGO) synthesis has been illustrated as a key step. The preparation of TiO2@rGO is highly needed and recommended to develop an effective way for the reduction of GO. Our study illustrated an environmentally simple method for TiO2@rGO preparation and demonstrated its efficiency for photocatalytic process by utilizing rhodamine-B dye as an organic pollutant. Synthesized nanoparticles of reduced TiO2@rGO have an observable increase in photo-energy adsorption leading to the increase of the photodegradation reactions. From the obtained results, TiO2@rGO nanocomposites showed great ability to absorb photo-energy and enhance the photodegradation reactions. Moreover, the results revealed that the 3% TiO2@rGO have the best performance than 1% TiO2@rGO at pH = 9.0, 30 mg/l initial dye concentration and 60 min irradiation duration. The reduced graphene oxide production was considered as an influential co-catalyst for improving the TiO2 photocatalytic activities mainly owing to; the fast separation of h+/e? and the adsorption improvement. Our study affirms the production of promising applicable particles using the environmental photocatalysis process in particular with regard to wastewater purification.
关键词： Photocatalysis,Graphene oxide,Nanocomposite,TEM,Rh-B dye,TiO2,XRD
更新于2025-09-10 09:29:36
-
Structure characterization and photoluminescence of sol-gel synthesized Ag-Dy-codoped silica phosphor
摘要： Bulk samples of single Ag-, Dy-doped and Ag-Dy-codoped silica matrices were synthesized using the sol-gel processing. These matrices were characterized using X-ray di?ractometry, ultraviolet-visible-near infrared (UV-VIS-NIR), Fourier transform infrared, photoluminescence (PL) excitation and emission spectroscopic techniques. High resolution transmission electron microscope con?rmed the presence of ?ne spherical Ag nanoparticles (NPs), whose average size is approximately 10–15 nm, in the Ag-doped and Ag-Dy-codoped silica matrices. UV-VIS-NIR spectra revealed absorption peaks due to Dy3+ active centers in addition to the surface plasmon resonance bands of Ag NPs centered at 410 and 452 nm in these matrices, respectively. UV-excited PL of the materials was studied and compared. Near-white light emission, which was assessed by the calculated CIE chromaticity coordinates, could be observed under UV excitation at 365 nm in the Ag-Dy-codoped silica matrix. This white light was realized by appropriate combination of prominent yellow and blue emissions. Electron spin resonance spectra revealed paramagnetic spin states for Ag which can be attributed to the quantum size e?ect of very ?ne Ag NPs dispersed in the silica network. The obtained results indicate that the Ag-Dy-codoped silica phosphor could be a promising candidate for application as white light emitting phosphor for UV LED chips.
关键词： Sol-gel,TEM,Surface plasmon resonance,Phosphors,White LED,Optical band gap
更新于2025-09-10 09:29:36
-
The influence of stopping power and temperature on latent track formation in YAP and YAG
摘要： Transmission electron microscopy techniques were used to analyse the effect of swift heavy ion irradiation on both yttrium aluminium perovskite (YAP) YAlO3, and yttrium aluminium garnet (YAG) Y3Al5O12 single crystals. The crystals were irradiated with Kr, Xe and Bi ions with energies ranging from 107 to 1030 MeV. These ions have electronic stopping powers in the range from 11 to 41 keV/nm. The ion fluences were all within the non-overlapping regime for latent ion tracks i.e. 1011–1012 cm?2. A number of crystals were also irradiated at different temperatures of 80, 300 and 1000 K at a fixed stopping power. Latent ion tracks with an amorphous core were observed in all samples. The track diameters were seen to increase with increasing stopping power. Track diameters only increase by a significant amount as a result of irradiation temperature at 1000 K, whereas the diameters at 80 and 300 K differ only slightly. Ion tracks in YAG were also found to be larger than those in YAP at comparable stopping powers. It was found that on average 10 keV/nm of extra energy input is required to produce ion tracks in YAP with diameters similar to those in YAG. The results also suggest that the complexity of the crystal structure plays a significant role in the formation of ion tracks in these crystals.
关键词： YAG,Radiation damage,YAP,Latent track,TEM,Swift heavy ion
更新于2025-09-10 09:29:36