- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Modeling and optimization of characterization of nanostructure anodized aluminium oxide membranes
摘要： This study indicates the importance of statistical analysis and modeling to investigate the synthesis and optimization of anodized aluminium oxide (AAO) properties for template-assisted synthesis of nanostructure particles. The response surface methodology was used to optimize pore size and porosity of AAO. The impacts of four main parameters including type of acidic electrolyte, concentration of acid, bath temperature and electrical potential of anodization on characterization of AAO were investigated. Statistical analysis showed that the linear and quadratic terms of these variables had significant effects. Based on the statistical analysis, a possible mechanism of the anodization was proposed. The proposed mechanism helped us to develop an analytical model. The analytical model could predict the experimental results with an appropriate accuracy. Results indicated the rate-limiting reaction in anodization process is water dissociation which was conducted at the pore bottom of the AAO. In addition, concentrated electrical field at pore base induced water splitting so that the activation energy of water dissociation decreased ten times and reached to 9898.5 J/mol.
关键词： Statistical analysis,Anodized aluminium oxide,Electrochemical synthesis,Pore perforation,Nanoporous materials
更新于2025-09-23 15:23:52
-
Influence of porosity and pore size on sputtering of nanoporous structures by low-energy Ar ions: Molecular dynamics study
摘要： In this paper we have carried out molecular dynamics simulation of the low-energy Ar ion irradiation of nanoporous homogeneous material with different porosity and pore sizes. Our results demonstrate that in a model with small pores (Rpore = 0.8 nm) and relatively low (22%) porosity, the pores at near-surface layers collapsed due to the ion bombardment, whereas in a model with larger pores (Rpore = 2.8 nm) and higher (44%) porosity no significant structural changes occurred under the same irradiation conditions. To study thermal stability of porous structures and to reveal the effects of both the pore radius and the porosity on pore collapsing, our nanoporous structures were subjected to gradual heating. The simulation results demonstrate distinct mechanisms of structural changes in the nanoporous materials depending on the value of the excess surface energy per unit volume.
关键词： low-k dielectrics,plasma treatment,nanoporous material,pore collapse,sputtering
更新于2025-09-23 15:23:52
-
Evolution of shapes and identification of level II and III features of fingerprints using CaZrO3:Sm3+ fluorescent markers prepared via solution combustion route
摘要： Simple solution combustion route is used for the fabrication of CaZrO3: Sm3+ (1–11 mol %) nanophosphors using Aloe Vera gel as a fuel. The powder X-ray diffraction profiles confirm the pure orthorhombic phase. The granular type particles with non-uniformity in the size is observed. Photoluminescence emission spectra exhibit intense peaks at ～571, 603, 651 and 708 nm, which are attributed to 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and 4G5/2 → 6H11/2 transitions of Sm3+ ions, respectively. The photometric properties evident that the prepared samples emit bright orange - red light with 79% color purity. The average correlated color temperature value is found to be ～3100 K. Thermoluminescence glow curves exhibit a broad, intense peak at ～148 °C. The highest thermoluminescence intensity is recorded for 5 mol % of Sm3+ doped sample. The thermoluminescence intensity at ～148 °C is found to increase with increase of γ-dose. The optimized CaZrO3:Sm3+ (5 mol %) nanophosphors used as a luminescent labeling agent for visualization latent fingerprints on various porous and non-porous surfaces under ultraviolet 254 nm and normal light. The obtained results exhibits well defined ridge details with high sensitivity, selectivity, and low background hindrance which showed greater advantages. Extensive fingerprint details, namely level II and III features are clearly revealed. Hence, aforementioned results evident that the optimized sample endorse wide spread of applications, namely solid state lighting, high temperature dosimetry and advanced forensic science fields.
关键词： Thermoluminescence,Photoluminescence,Sweat pore visualization,Solution combustion,Photometric properties
更新于2025-09-23 15:23:52
-
Microfluidic Sensors with Impregnated Fluorophores for Simultaneous Imaging of Spatial Structure and Chemical Oxygen Gradients
摘要： Interior surfaces of polystyrene microfluidic structures were impregnated with the oxygen sensing dye Pt(II) tetra(pentafluorophenyl)porphyrin (PtTFPP) using a solvent-induced fluorophore impregnation (SIFI) method. Using this technique, microfluidic oxygen sensors are obtained that enable simultaneous imaging of both chemical oxygen gradients and the physical structure of the microfluidic interior. A gentle method of fluorophore impregnation using acetonitrile solutions of PtTFPP at 50oC was developed leading to a 10-μm-deep region containing fluorophore. This region is localized at the surface to sense oxygen in the interior fluid during use. Regions of the device that do not contact the interior fluid pathways lack fluorophores and are dark in fluorescent imaging. The technique was demonstrated on straight microchannel and pore network devices, the latter having pillars of 300 μm diameter spaced center to center at 340 μm providing pore throats of 40 μm. Sensing within channels or pores, and imaging across the pore network devices were performed using a Lambert LIFA-P frequency domain fluorescence lifetime imaging system on a Leica microscope platform. Calibrations of different devices prepared by the SIFI method were indistinguishable. Gradient imaging showed fluorescent regions corresponding to the fluid pore network, dark pillars, and fluorescent lifetime varying across the gradient, thus providing both physical and chemical imaging. More generally, the SIFI technique can impregnate the interior surfaces of other polystyrene containers, such as cuvettes or cell and tissue culture containers, to enable sensing of interior conditions.
关键词： Oxygen,sensor,impregnation,fluorophore,chemical imaging,pore network,polystyrene,microfluidic
更新于2025-09-23 15:22:29
-
Surface structural alteration of multi-walled carbon nanotubes decorated by nickel nanoparticles based on laser ablation/chemical reduction methods to enhance hydrogen storage properties
摘要： The catalytic effect of nickel is addressed to decorate the multi-walled carbon nanotubes for the purpose of hydrogen storage. The hydrogen sorption/desorption are investigated using the volumetric technique. Nickel nanoparticles are distributed on the surface of nanotubes using the laser ablation/chemical reduction treatments. The hydrogen uptake is elevated at higher nickel population up to a certain value and then experiences a significant drop for larger nickel content. The laser treatment is accompanied by the induced pores around nanotubes. This gives rise to the creation of the larger pores at higher laser doses leading to decrease the hydrogen trapping. Despite the pore size distribution strongly alters during both synthesis methods, however the abundance of small pore size in laser treatments is relatively higher than the that of the other technique. In comparison, the laser ablation demonstrates a relatively smaller desorption temperature against chemical one, mainly owing to the formation of larger pore size/volume. Generally, the hydrogen trapping efficiently takes place in the laser treated samples against chemical reduction method. The highest value of hydrogen storage ~1% (0.6% weight) is corresponding to 12.3% (13% weight) of nickel loading via the laser ablation (chemical reduction).
关键词： Hydrogen uptake,Nickel nanoparticles,Laser ablation,Chemical reduction,Pore size
更新于2025-09-23 15:22:29
-
<i>(Invited)</i> Electrochemical Formation of Nanoporous Indium Phosphide in KOH Electrolytes
摘要： Anodization of highly doped n-InP in KOH can result in a nanoporous sub-surface layer. Pores originate from surface pits and an isolated porous domain is initially formed beneath each pit. Domains are separated from the surface by a thin non-porous layer and each is connected to the electrolyte by its pit. Pores emanate along the <111>A directions to form truncated tetrahedral domains. We propose a three-step model of electrochemical pore formation: (1) hole generation at pore tips, (2) hole diffusion and (3) electrochemical oxidation of the semiconductor to form etch products. Step 1 determines the overall etch rate. However, if the kinetics of Step 3 are slow relative to Step 2, then etching can occur at preferred crystallographic sites leading to pore propagation in preferential directions. Pore width decreases with increasing anodization temperature and with increasing KOH concentration up to 9 mol dm-3, above which it decreases. At low current densities pores have sharp tips and triangular cross-sections; at higher current densities, the pore tips and cross-sections become more rounded while the pore width decreases. These observations are explained by the three-step model.
关键词： electrochemical formation,nanoporous,pore propagation,indium phosphide,KOH electrolytes
更新于2025-09-23 15:21:01
-
Direct observation of pore formation mechanisms during LPBF additive manufacturing process and high energy density laser welding
摘要： Laser powder bed fusion (LPBF) is a 3D printing technology that can print parts with complex geometries that are unachievable by conventional manufacturing technologies. However, pores formed during the printing process impair the mechanical performance of the printed parts, severely hindering their widespread application. Here, we report six pore formation mechanisms that were observed during the LPBF process. Our results reconfirm three pore formation mechanisms - keyhole induced pores, pore formation from feedstock powder and pore formation along the melting boundary during laser melting from vaporization of a volatile substance or an expansion of a tiny trapped gas. We also observe three new pore formation mechanisms: (1) pore trapped by surface fluctuation, (2) pore formation due to depression zone fluctuation when the depression zone is shallow and (3) pore formation from a crack. The results presented here provide direct evidence and insight into pore formation mechanisms during the LPBF process, which may guide the development of pore elimination/mitigation approaches. Since certain laser processing conditions studied here are similar to the situations in high energy density laser welding, the results presented here also have implications for laser welding.
关键词： Pore formation,Laser powder bed fusion,X-ray imaging,Laser welding,Additive manufacturing
更新于2025-09-23 15:21:01
-
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
-
Atomic layer deposition for membrane interface engineering
摘要： In many applications, interfaces govern the performance of membranes. Structure, chemistry, electrostatics, and other properties of interfaces can dominate the selectivity, flux, fouling resistance, and other critical aspects of membrane functionality. Control over membrane interfacial properties, therefore, is a powerful means of tailoring performance. In this Minireview, we discuss the application of atomic layer deposition (ALD) and related techniques in the design of novel membrane interfaces. We discuss recent literature in which ALD is used to (1) modify the surface chemistry and interfacial properties of membranes, (2) tailor the pore sizes and separation characteristics of membranes, and (3) enable novel advanced functional membranes.
关键词： membrane interface engineering,pore size tuning,surface modification,functional membranes,atomic layer deposition
更新于2025-09-19 17:15:36
-
Mechanisms limiting the release of TiO2 nanomaterials during photocatalytic cement alteration: the role of surface charge and porous network morphology
摘要： Nanomaterials have been widely used in a wide range of manufactured products in order to improve / add new properties. Photocatalytic cement maintains clean and white wall fronts and also provide interesting air pollution-reducing properties due to photocatalytic activity of incorporated TiO2-NMs. However, despite these environmental benefits, there is evidence of the release of TiO2-NMs during cement use. Therefore, it is crucial to understand the parameters controlling TiO2-NMs release. Zêta potentials of TiO2-NMs were investigated from the unaltered core to the cement altered surface using simulated cement pore waters. The mineralogy and chemical composition of the altered layer were investigated using X-ray Diffraction (XRD) and micro X-ray fluorescence spectroscopy (micro-XRF). Finally, pore network morphology was fully analyzed using X-ray computed tomography at both micro and nano-scales (micro and nano-CT) and quantified using 3D morphological software (i-Morph). This study provides evidence that the TiO2-NMs release comes from a very thin “active surface layer” (thickness less than 20 μm) where both cement surface chemistry and the pore network appears to be favorable for the TiO2-NMs diffusion. The pore volume connected to the surface with a throat size ≥1016 nm appears to control and be used as a predictor for TiO2-NMs release.
关键词： Life cycle,exposure,3D imaging,pore throat size,micro and nano X-ray computed tomography (micro and nano-CT)
更新于2025-09-19 17:15:36