Ag Agglomeration Research Articles

High-Performance Photocatalytic Multifunctional Material Based on Bi4Ti3O12-Supported Ag and Ti3C2Tx for Organic Degradation and Antibacterial Applications

With the rapid development of modern science and technology and the diversification of social needs, traditional single-performance materials struggle to meet the complex and changeable application scenarios. To address the multifaceted requirements of biomedical applications, such as disease diagnosis and treatment, scientists are dedicated to developing new multifunctional biomaterials with multiple activities. Bi4Ti3O12 (BTO), despite its versatility and application potential, has insufficient photocatalytic performance. Silver nanoparticles (Ag) and Ti3C2Tx are particularly effective as antibacterial materials but they have relatively single functions. In this study, BTO/Ag/Ti3C2Tx biomultifunctional materials were constructed by combining BTO with Ag and Ti3C2Tx. We discovered that the addition of Ag and Ti3C2Tx effectively optimized the visible light absorption characteristics of BTO, reduced the electron transfer resistance, and increased the carrier concentration, thus significantly improving the photocatalytic performance of composite material, thereby markedly improving the composite’s photocatalytic performance and its efficacy in photochemical sensing and photodegradation. At the same time, BTO, as a carrier, effectively avoids Ag and Ti3C2Tx agglomeration and gives full play to its antibacterial properties. In the specific performance studies, ascorbic acid and MB were used as the subjects of photochemical sensing and photodegradation properties, while Escherichia coli and Staphylococcus aureus were tested for antibacterial properties. The BTO/Ag/Ti3C2Tx composite showed remarkable results in all assessments, demonstrating its potential as a versatile antibacterial and photocatalytic material.

Magnetoplasmonic core–shell structured Ag@Fe3O4 particles synthesized via polyol reduction process rendering dual-functionality for bacteria ablation and dyes degradation

The Ag nanoparticles demonstrate potent bacteria eradication capabilities; however, their tendency to aggregate in aqueous solutions compromises the antibacterial efficacy. Furthermore, the Ag nanoparticles employed in sewage treatment are challenging to recycle, resulting in environmental pollution and resource wastage. Herein, the Ag-core Fe3O4-shell structured particles (Ag@Fe3O4) are synthesized by leveraging the reduction potential difference between Ag+/Ag0 and Fe3+/Fe2+ through a one-step polyol reduction process. The Fe3O4 shell in the Ag@Fe3O4 composite not only effectively inhibits the agglomeration of Ag, but also enhances the penetration capability of the composite into biofilms, thereby enabling Ag@Fe3O4 to possess remarkable antibacterial efficacy against Escherichia coli (E. coli). The Ag@Fe3O4 demonstrates nearly 100 % inhibition of E. coli at a concentration of 0.24 mg mL−1 (with an Ag content of 0.042 mg mL−1) while still maintaining antibacterial effectiveness of 74.6 % even after undergoing reutilization for 10 cycles. Meanwhile, due to the excellent electron conductivity of Ag and the effective adsorption capability of Fe3O4 shell towards organic dyes, Ag@Fe3O4 facilitates rapid electron transfer to organic dyes and further lead to their reduction and degradation in the presence of NaBH4. The Ag@Fe3O4 can catalytically degrade various organic dyes (including Rhodamine B, Rhodamine 6G, and Methylene blue) within only 15 min, while achieving an impressive degradation efficiency exceeding 90.9 % after 6 cycles of reutilization. The cost-effectiveness (approximately $0.17 per gram), facile magnetic recovery, along with the superior antibacterial and dye-degradation performance showcase the significant potential of Ag@Fe3O4 for medical applications and sewage treatment.

Silver and g-C3N4 co-modified biochar (Ag-CN@BC) for enhancing photocatalytic/PDS degradation of BPA: Role of carrier and photoelectric mechanism

Photocatalytic property of nano Ag is weak and its enhancement is important to enlarge its application. Herein, a novel strategy of constructing silver g-C3N4 biochar composite (Ag-CN@BC) as photocatalyst is developed and its photocatalytic degradation of bisphenol A (BPA) coupled with peroxydisulfate (PDS) oxidation process is characterized. Characterization result showed that silver was evenly embedded into the g-C3N4 structure of the nitrogen atoms format, impeding agglomeration of Ag by distributing stably on biochar. In optimum condition, BPA of 10 mg/L could be degraded completely at pH of 9.0 with a 0.5 g/L photocatalyst, 2 mM PDS in Ag-CN@BC-2 (Ag/melamine molar ratio of 0.5)/PDS system (99.2%, k = 4.601 h−1). Ag-CN@BC shows superior mineralization ratio in degrading BPA to CO₂ and H₂O via active radical way, including holes (h⁺), superoxide radicals (•O2⁻), sulfate radicals (SO4•⁻), and hydroxyl radicals (•OH). Proper amount of silver can be dispersed effectively by gC3N4, which is responsible for improving the visible-light absorbing capability and accelerate charge transfer during activation of PDS for BPA degradation, while biochar as carrier in the composite is supposed to enhance the photoelectric degradation of BPA by reducing the band gap and increasing the photocurrent of Ag-CN@BC catalyst. Ag-CN@BC exhibits excellent catalyst stability and photocatalytic activity for treatment of toxic organic contaminants in the environment.

Oriented attachment of silver nanoparticles in DMSO by collapsing under thermal stress

Nowadays, understanding the behavior of nanoparticle agglomeration is crucial to gain insight into the fundamental physicochemical processes that govern particle interactions at the nanoscale. In this work, we are focused on the thermal collapse of silver nanoparticles (NPs) stabilized with sodium citrate in dimethyl sulfoxide (DMSO). Therefore, we investigated the parameters that influence the transition from nearly isolated particles to elongated Ag agglomerates using Dynamic Light Scattering (DLS) and Ultraviolet-Visible Spectroscopy (UV-Vis). In addition, we conducted an in-depth study of the near-particle-particle interaction within the agglomerate using High-Resolution Transmission Electron Microscopy (HRTEM) observations of the agglomerates. The HRTEM results suggest that in the elongation of the agglomerate, the oriented attachment within the initial cluster plays a crucial role in the alignment along the longitudinal axis. The aging colloid exhibits minimal agglomeration, suggesting that the driving force of the collapse phenomenon is predominantly thermodynamic rather than kinetic in nature, and that the surface chemical equilibria play a key role in the preferential orientation mechanism.

Effect of Ag agglomeration-driven nanovoids formation on fatigue reliability of Cu–Ag alloy flexible interconnects

Fatigue failure under cyclic deformation remains longstanding challenge in the flexible interconnect for the long term application. In this study, we design Cu–Ag alloy interconnects with excellent fatigue resistance by adopting nanovoid structures acquired by a simple post-annealing process. Nanovoids are generated during Ag agglomeration in the Cu matrix because of the low solubility of Ag in Cu, which enhances the fatigue property of a Cu–Ag alloy deposited on a polyimide film. The effect of high-density nanovoids located at the triple junction of the Cu and Ag grain boundaries on the mechanical fatigue lifetime is investigated by microstructure analysis (HAADF, HR-TEM and ASTAR™-coupled TEM). The fatigue damage of the Cu–Ag alloy has been observed to originate from grain boundary decohesion, unlike typical long fatigue cracks and extrusions. This can be attributed to the uniform distribution of nanovoids, which leads to stress concentration relief and consequently reduces the level of deformation.

Silver decoration of Cr2O3 nanoparticles: Facile preparation of Cr2O3 nanoparticles and Ag–Cr2O3 nanocomposites and characterization of their antibacterial activity and ability to photocatalytically degrade organic wastes under visible light

An eco-friendly, single-step process was adopted for the preparation of Cr2O3 nanoparticles (CR-NPs), and different concentrations of Ag were doped into the CR-NPs through liquid impregnation to synthesize a series of Ag-CRNPs composites. In order to prevent agglomeration, chemical transformation, and weak adhesion of Ag to CR-NPs, a mechanical process of circular-motion grinding and high-temperature treatment in a sealed condition were used. Well-defined heterojunctions were successfully formed between Ag and CR-NPs. In comparison to the CR-NPs, the Ag-doped CR-NP composites exhibited excellent performance in photocatalytic and antibacterial applications. Under visible light (VL), the best-performing composite (2 %-Ag decorated CR-NPs) showed 96 %, 79 %, and 57 % decomposition of methylene blue, Congo red, and tetracycline, respectively, in 100 min, which was attributed to a synergetic effect in the composites. The rate constant of the photocatalytic reaction is 14 times higher than that of the reaction without a photocatalyst. The enhanced efficiency was attributed to a reduced bandgap, prolonged retention of photogenerated electron–hole pairs, an increased amount of active spots, and increased absorption of VL. Similarly, the best-performing composite exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus with zones of inhibition of 15.4 and 15.1 mm, respectively. The 2 %-Ag decorated CR-NPs were the most efficient and exhibited robust recyclability until the fifth cycle (≥90 %). The photocatalytic activity was primarily driven by reactive oxygen species, holes and hydroxyl radicals.

Linking Multicomponent Interactions of Catalyst Ink and Catalyst Layer Fabrication with Electrochemical CO2 Reduction Performance

The controllable fabrication of catalyst layers (CL) by tuning the multiscale structure formation is complex but vital to achieving optimum CO2 reduction (CO2R) performance. The CL formation is deeply influenced by catalyst ink. An in-depth understanding on the role of each catalyst ink component and how multicomponent interactions affect ink status, catalyst layer structure, and CO2R performance is crucial.In this work, the roles of various ingredients of catalyst ink were systematically investigated from simple binary inks to complete catalyst inks. Our results showed Ag agglomerates can be broken down more efficiently in water than in alcohols due to stronger inter-particle repulsive forces induced by water disassociation. Ag particles-Nafion networks were found to play a decisive role in stabilizing catalyst ink, mitigating agglomeration and particle sintering. The catalyst ink was comprehensively characterized and reported by static multiple light scattering (SMLS) for the first time in this study. The evolution of catalyst ink was identified in three stages: stable, flocculation and sedimentation. Isopropanol (IPA)-rich solvents were demonstrated to be more effective in stabilizing catalyst ink due to better dispersed Nafion aggregates and further enhanced Ag particle-Nafion interactions.Subsequently, catalyst layer structure and CO2R performance were correlated with multi-component interactions in catalyst ink. Strong Ag particle-Nafion interactions were proven to promote not only ink stability, but also catalyst layer homogeneity and reaction site distribution. Water-rich inks helped improve the porosity and durability of GDEs. The cathodic potential of GDEs made by 70%-water inks (-0.75 V vs. NHE) was 30% lower than zero-water inks (-1.1 V vs. NHE), and the highest CO selectivity was boosted to 97% at an industrial meaningful current density of 200 mA/cm2 by enhancing Ag particle-Nafion interactions through rational design of ink formulation, dispersing and fabrication processes.Simultaneously, a scalable manufacturing methodology of robust GDE was developed and validated to achieve optimal CO2R performance. It will not only provide a meaningful reference for lab applications (fast and reproducible GDE fabrication aiming at new catalysts, ionomers, membranes or operation conditions development), but also provide a steppingstone to industrial applications (GDE fabrication aiming at large scale, good durability and quality of conformance). Figure 1

Enhanced p-type Ohmic contact performance in FCLEDs by manipulating thermal stress distribution to suppress Ag agglomeration

The implementation of reflective p-type Ohmic contact is an effective way to solve current crowding and improve the optoelectronic performance of flip-chip light-emitting diodes (FCLEDs). Here, we investigate the effects of annealing temperature, annealing time, and N2 flow rate on the formation for Ag/p-GaN Ohmic contact and determine the optimal annealing process parameters. After inserting an indium-tin oxide layer between Ag and p-GaN, the specific contact resistance decreases from 6.66 × 10−3 to 1.86 × 10−3 Ω cm2. In addition, we discover the appearance of a “black line” around the edges of the chips after high-temperature annealing. Finite element analysis and experiments show that the “black line” is related to Ag agglomeration under high temperatures due to stress concentration at the edges of the chips. A strategy for manipulating the stress concentration by adjusting the thickness of the TiW diffusion barrier layer is proposed based on insight obtained by modeling the stress distribution at the edge of the chips. The electrical properties of the fabricated FCLEDs show that the proposed stress manipulation strategy solves the problem of “black line” effectively and maintains the performance of the chips well.

Enhanced mechanical and biocompatibility performance of Ti(1-)Ag(x) coatings through intermetallic phase modification

Advanced materials combining superior mechanical and biocompatibility performance are of significant interest to extend the lifetime of biomedical devices. In this work, Ag is alloyed with Ti to investigate the role of emerging Ti Ag intermetallic coatings with high mechanical hardness and exceptional biocompatibility. Thin films of Ti (1- x ) Ag (x) were deposited on 316 L steel and glass substrates using magnetron sputtering and subsequently heat-treated to aid Ti Ag intermetallic development. Mechanical properties were then measured and correlated to microstructural and morphological changes in the Ti Ag films. In the as-grown state, the Ti Ag matrix developed different intermetallic structures which increased the hardness of pure Ti films from 5 to >7 GPa. After heat treatment, a peak hardness of 7.39 GPa and elastic modulus of 105 GPa was achieved for a 43 at.% Ag film due to formation of the tetragonal Ti Ag phase and increase of upper surface oxides which act as dislocation barriers. However, at higher Ag concentrations, heat treatment leads to agglomeration of Ag around grain boundaries and decreases the crystallite size, leading to reduction in hardness to <3 GPa. The Ti rich films also depict better cytotoxicity performance following exposure to the L929 cell line, though excellent cell viability values >98% are observed for the entire Ti Ag range. While leached ion concentrations lower than 100 ppb demonstrate excellent biocompatibility of this Ti Ag alloy system. This work demonstrates the first successful attempt to develop biocompatible Ti Ag thin film coatings with high mechanical hardness with the potential to extend the lifetime of medical implants. • First study on biomechanical performance of Ti (1-x) -Ag (x) intermetallic films. • First report on external heat treatment to develop Ti Ag intermetallic thin films. • Ag addition causes transition to tetragonal Ti Ag structure with enhanced hardness. • Heat treatment leads to improved crystallinity and mechanical performance. • Ti Ag films exhibit excellent biocompatibility before and after heat treatment.

Nanocomposite Mo-Ag-N lubricating, wear resistant and hard coatings fabricated by magnetron sputtering

Mo-Ag-N coatings were prepared by d.c. magnetron sputtering technique from a Mo target with embedded Ag pellets, followed by vacuum annealing at 425, 500, and 600 °C, respectively, for 1 h. SEM, EDS, XRD, nanoindenter, and micro–macro tribometer were used to investigate the influence of Ag content and annealing temperature on their microstructure, surface morphology and mechanical properties. Results demonstrated that as-deposited Mo-Ag-N coatings consisted of fcc γ-Mo2N phase and fcc Ag phase where Ag uniformly distributed into Mo-N matrix. The hardness of Mo-Ag-N coatings initially increased and then decreased with Ag content, reaching the maximum hardness of 32 GPa at 4 at.% Ag, whereas friction coefficient decreased monotonously with Ag content increasing. With the increase of annealing temperature hardness, friction coefficient, and wear resistance were decreased due to the accumulation of a large amount of Ag agglomerates onto surface resulted from high temperature intriguing phase segregation and diffusion.

Fabrication of Ta-Ag composite deposits via cold spray: Investigation of bonding mechanism and deposition behavior

Cold spray is a solid-state deposition technology that can achieve deposition of pure metal, alloys, and composites with high efficiency. By taking the advantage of cold spray method, in this work, Ta and Ag were successfully used to fabricate Ta-Ag composite deposits for the first time, despite their significantly different properties. It was found that mechanical bonding was the major deposition mechanism between Ta and Ag. The Ag volume in the mechanically mixed powder influence the deposition between Ag and Ta particles. Deposition of Ta-Ag powder was same as pure Ta powder when Ag volume was low, and the small volume of deposited Ag inhibit the deposition of Ta particles. Higher Ag volume in powder promoted the deposition of Ta particles via mechanical interlocking due to the formation of large Ag agglomerates.

Embedded Oxidized Ag-Pd-Cu Ultrathin Metal Alloy Film Prepared at Low Temperature with Excellent Electronic, Optical, and Mechanical Properties.

Most transparent conducting materials are based on Sn:In2O3 (ITO). When applied onto flexible substrates, ITO can be prepared in an oxide–metal–oxide (OMO) configuration, typically ITO/Ag/ITO, where the ductility of the embedded metal layer is intended to reduce the mechanical brittleness and improve the electrical conductivity of the OMO multilayer. Hitherto, the lower limit of the thickness of the Ag layer has been limited by the percolation threshold, which limits the Ag layer to be thicker than ∼10 nm to avoid agglomeration and to ensure conductivity and structural stability. Metal layers of thicknesses below 10 nm are, however, desirable for obtaining OMO coatings with better optical properties. It is known that agglomeration of the metal layer can, to some extent, be suppressed when substituting Ag by an Ag–Pd–Cu (APC) alloy. APC-based OMO films exhibit excellent optical and electrical properties, but still continuous APC films well below 10 nm thickness cannot be achieved. In this work we demonstrate that controlled oxidation of APC results in smooth, ultrathin APC:O continuous coatings (of thickness ∼5 nm) on ITO-coated PET substrates. Moderate oxidation yields superficial PdOx formation, which suppresses Ag agglomeration, while still maintaining excellent conductivity. On the other hand, extensive oxidation of APC leads to extensive Pd oxide nucleation deteriorating the conductivity of the film. The ITO/APC:O/ITO films exhibit low resistivity, attributed to a high Hall mobility associated with suppressed agglomeration, good stability in high humidity/temperature environments, superior transmittance in the visible and infrared region, and excellent mechanical bending properties, thus providing new opportunities for fabricating superior transparent conducting coatings on polymer substrates.

Ag/biochar nanocomposites demonstrate remarkable catalytic activity towards reduction of p-nitrophenol via restricted agglomeration and leaching characteristics

The rapid reduction of p-nitrophenol by sodium borohydride in presence of Ag/biochar nanocomposites is demonstrated. These nanocomposites were synthesized by deposition of silver nanoparticles on Cymbopogon citratus-derived biochar. Structural and morphological features of the nanocomposite was investigated by XRD and electron microscopy respectively. Catalytic activity of Ag/biochar was found to be remarkably higher than that of Ag nanoparticles and biochar. Effect of various reaction parameters was investigated experimentally and also scrutinized using Response Surface Methodology (RSM) and Artificial Neural Network (ANN). According to the RSM, the maximum efficiency of conversion predicted was up to 98% of p-nitrophenol was converted to p-aminophenol when the Ag-biochar ratio was approximately 1:0.006. Furthermore, an ANN model was built which supported the accuracy of the prediction models. The catalytic activity of Ag/biochar nanocomposites which remained nearly unaltered for 5 consecutive cycles was expected to be due to restriction of agglomeration and leaching of Ag.

Comparison of Aerosol Pt, Au and Ag Nanoparticles Agglomerates Laser Sintering.

In this paper, we investigated the interaction of nanosecond pulsed-periodic infrared (IR) laser radiation at a 50 and 500 Hz repetition rate with aerosol platinum (Pt) and silver (Ag) nanoparticles agglomerates obtained in a spark discharge. Results showed the complete transformation of Pt dendrite-like agglomerates with sizes of 300 nm into individual spherical nanoparticles directly in a gas flow under 1053 nm laser pulses with energy density 3.5 mJ/cm2. Notably, the critical energy density required for this process depended on the size distribution and extinction of agglomerates nanoparticles. Based on the extinction cross-section spectra results, Ag nanoparticles exhibit a weaker extinction in the IR region in contrast to Pt, so they were not completely modified even under the pulses with energy density up to 12.7 mJ/cm2. The obtained results for Ag and Pt laser sintering were compared with corresponding modification of gold (Au) nanoparticles studied in our previous work. Here we considered the sintering mechanisms for Ag, Pt and Au nanoparticles agglomerates in the aerosol phase and proposed the model of their laser sintering based on one-stage for Pt agglomerates and two-stage shrinkage processes for Au and Ag agglomerates.

Ag/Ce0.9Gd0.1O2- δ Based Vertically Aligned Nanocomposite Thin Film Electrodes for Low-Temperature Solid Oxide Cells

Low temperature solid oxide cells (LT-SOCs, 300-500°C) have become the "next generation" technology following the commercialized high temperature SOCs (650–850 °C). The current research is focused on screening new materials and microstructural designs that are ideal for low-temperature operations. This study explores the vertically aligned nanocomposite (VAN) heterostructure design, which has been shown to provide novel properties and new functionalities at the heterointerfaces of two oxide materials.1 In this design, we combine two materials known to show exceptionally fast electrokinetics at low temperatures. However, instead of two oxide materials, we explore a combination of electronically conducting metal and an ionically conducting oxide. The electrode composed of Ag and Ce0.9Gd0.1O2-d (CGO) is deposited epitaxially on oriented yttria-stabilized zirconia substrates by pulsed laser deposition. Silver is a highly active catalyst for oxygen reduction reactions (ORR), exhibits high electrical conductivity at low temperatures and is resistant to oxidation in air, but has a relatively low melting point and agglomerates easily in air. Therefore, it is necessary to prevent Ag agglomeration during operation. Addition of CGO is expected to (i) stabilize Ag by surrounding it through vertically grown columns and (ii) extend the ionically conducting path onto the cathode and share the oxygen ion diffusion pathway with Ag.2 Preliminary results show successful growth of ~40 nm thick oriented Ag/CGO VAN films. The investigations will be complemented with electrochemical performance and stability measurements using impedance spectroscopy. This study will provide insights into enhanced ORR performance at low temperatures by controlling crystal orientation and strain tuning at the metal/oxide VAN heterointerfaces. J. Huang, W. Li, H. Yang and J. L. MacManus-Driscoll, MRS Bull., 2021, 46, 159–167.H. R. Choi, K. C. Neoh, H. J. Choi, G. D. Han, D. Y. Jang, D. Kim and J. H. Shim, J. Power Sources, 2018, 402, 246–251.

Regulating Ag Wettability via Modulating Surface Stoichiometry of ZnO Substrates for Flexible Electronics

AbstractA novel and highly efficient methodology to regulate (enhance or suppress) the Volmer–Weber 3D growth mode of ultra‐thin (&lt;10 nm) Ag layers by modulating the surface stoichiometry of ZnO substrates prior to Ag deposition is presented. Relative to pristine ZnO layers, oxygen‐deficient surface states formed by preferential removal of surface oxygen atoms remarkably improve Ag layer wettability, whereas oxygen‐excessive surface states formed by oxygen atom incorporation strongly facilitate Ag agglomeration. The dissimilar nucleation and coalescence dynamics are elucidated via combined molecular dynamics and force‐bias Monte Carlo simulations. The improved wettability results in significantly lower sheet resistance in the ultra‐thin (6–10 nm) Ag layers, for example, 6.03 Ωsq−1 at 8 nm, than the previously reported values from numerous other approaches in the equal thickness range. When this unique methodology is applied to ZnO/Ag/ZnO transparent electrodes, simultaneous improvement in electrical conductivity and visible transparency is realized, with a resultant Haacke figure of merit value of 0.139 Ω−1 that is &gt;50% higher than the best reported value for an identically structured electrode. We select transparent heating devices as a model system to confirm that the superior optoelectronic properties are highly sustainable under simultaneous and severe electrical, mechanical, and thermal stresses.

A Novel Preparation of Ag Agglomerates Paste with Unique Sintering Behavior at Low Temperature.

A novel bonding process using Ag agglomerates paste prepared by Ag2O reduction has been proposed, which solved the problem of Cu substrate oxidation in the conventional Ag2O sintering process for Cu–Cu bonding. By applying the Ag agglomerate paste to Ag–Ag bonding, a shear strength of 28.3 MPa at 150 °C was obtained. Further studies showed that the optimum sintering temperature was at 225 °C, and a shear strength of 46.4 MPa was obtained. In addition, a shear strength of 20 MPa was obtained at 225 °C for Cu–Cu bonding. Compared to common Ag pastes, the results in this paper revealed that the sintering behavior of Ag agglomerates was unique, and the sintering mechanisms for Ag–Ag and Cu–Cu bonding were also discussed.

Experimental and numerical investigation on the structure characteristics of vortex generators affecting particle agglomeration

Particle agglomeration in turbulent flows plays an important role in the formation process of atmospheric pollution and the control technology of fine particulate matter. In this work, an experimental platform was built to study the structure characteristics, including geometric size, row number, spanwise pitch, longitudinal pitch and arrangement, of the vortex generators affecting the particle agglomeration. At the flow velocity of 4.8 m/s, the optimal agglomeration efficiency within the particle size range of 15.7–850.0 nm is about 16.42%. The three agglomeration morphologies of multi-branched particle tree, long strip-shaped particle chain and stacked particle ball are observed and characterized through the three parameters of void content, degree of sphericity and dynamic shape factor. Moreover, a numerical model, considering the Brownian collision of the slip flow regime and the aerodynamic collision of the inertialess particles, was developed to analyze the distribution and collision of the particles in the vortexes. The simulation results indicate that the windward boundary layers of the vortex generators and the longitudinal edges of the vortexes are main areas where collision and agglomeration occur. Under the staggered arrangement, the windward boundary layers are beneficial to facilitate the transverse motion of particles, but also form the transverse local enrichment. Finally, a dimensionless criteria Ag (Agglomeration number, abbreviated as Ag) was put forward to evaluate the agglomeration ability of the vortex generator.

Highly reliable and transparent Al doped Ag cathode fabricated using thermal evaporation for transparent OLED applications

Abstract Here, we report a highly reliable and transparent cathode (TC) for transparent organic light emitting diode (TOLED) applications. The cathode layer is fabricated by co-deposition of silver (Ag) and aluminum (Al) metals using thermal evaporation. The atomic percentages of Al and Ag are fixed at 96 at% and 4 at%, respectively. TC shows transmittance at 520 nm (T@520nm) of 83.5% and sheet resistance as low as 7.0 Ω/□. Almost no specific agglomeration of Ag:Al (4%, 14 nm) is noticed by the thermal annealing of fabricated cathode at 85 °C, 240 h. The fabricated TOLED with this Ag:Al (4%, 14 nm) cathode shows an excellent electron injection property with a T@520nm of 83.5%, and achieved current efficiencies of 36 and 18 cd/A from bottom and top sides emissions, respectively. It is argued that the Al-doped Ag film could become an effective, feasible alternative to the existing transparent conducting electrode for TOLED applications.

Surface microstructure and mechanical properties of Ti-6Al-4V/Ag nanocomposite prepared by FSP

The surface microstructure and mechanical properties of Ti-6Al-4V/Ag nanocomposite processed by friction stir processing (FSP) are studied in this work. Scanning electron microscope (SEM) results show the gradient grain size of surface layer. The pile-up and tangle of dislocations and the deformation twins are observed by transmission electron microscopy (TEM). Atom probe tomography (APT) analyses reveal the presence of Ag-enriched nanoparticles in both the interiors and boundaries of α-Ti grains. Severe plastic deformation via FSP is responsible for considerable dislocations pile-up and tangle in the deformation bands. The enhancement in hardness and elastic modulus is attributed to the grain refinement and formation of much more deformation twinning. Moreover, Ag agglomeration could accelerate the recrystallization process and prevent grain coarsening, resulting in the higher hardness and the larger elastic modulus. This study confirms FSP is effective on surface modification of titanium alloys for improving the surface mechanical properties.