13,768 research outputs found
Development of high concentrated aqueous silver dispersion for inkjet printing on ceramic substrates
No full textIn this paper, the formulation of a high Ag loading (45 wt %) aqueous ink and
its subsequent printing on three different ceramic substrates were reported.
Monodispersed Ag nanoparticles with a size down to 10 nm were successfully
synthesized in aqueous medium. These nanoparticles were then successfully
dispersed up to 45 wt% in aqueous medium with the aid of a co-polymer, Pluronic
F127. The printed tracks show the electrical conductivity of 3μΩcm close to the
value of silver bulk (1.6 μΩcm). The use of high solid loading inks reduces the
number of printed layers required for thick, dense and conductive film thus
leading to the reduction of the costs, and high efficiency of the printing
process. High solid loading also results in the finer printed features. The
effect of substrates, printing temperature and dot spacing on the size and
morphology of printed silver features was investigated. Increasing the dot
spacing together with the substrates temperature resulted in the limited ink
spreading, hence narrow printed line and improved geometry of printed patt
Polarization dependence of the light coupling to surface plasmons in an Ag nanoparticle & Ag nanowire system
No full textPolarization dependence of the coupling of excitation light to surface plasmon polaritons (SPPs) was investigated in a Ag nanoparticle-nanowire waveguide system (a Ag nanoparticle attached to a Ag nanowire). It was found that under the illumination of excitation light on the nanoparticle-nanowire junction, the coupling efficiency of light to SPPs depends on the polarization of the excitation light. Theoretical simulations revealed that it is the local near-field coupling between the nanoparticle and the nanowire that enhances the incident light to excite the nanowire SPPs. Because the shapes of the Ag nanoparticles differ, the local field intensity, and thus the excitement of the nanowire SPPs, vary with the polarization of the excitation light.Physics, MultidisciplinarySCI(E)EI中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)[email protected]
Effects of shell thickness on the thermal stability of Cu-Ag core-shell nanoparticles: A molecular dynamics study
No full textCu-Ag core-shell (CS) nanoparticle (NP) is considered as a cost-effective alternative material to nano silver sintering material in die attachment application. To further reduce the cost, the thickness of the Ag shell can be adjusted. Whereas the shell thickness will also affect the thermal stability of the Cu-Ag CSNPs. In this study, molecular dynamics simulation was applied to study the thickness effect on the thermal behavior of Cu-Ag CSNPs. The melting points of CSNPs and Pure NPs can be determined by the evolutions of Potential Energy (PE), and the Lindemann index (LI) of the system. The results indicated that the melting points of CS NPs were lower than monometallic NP and the melting point of CS NP is influenced by the size of the Cu core and the number of lattice mismatches. Moreover, the distribution of atoms’ LI showed that the premelting point is independent of shell thickness. However, the fraction of atoms that occurred premelting is increased with the decrease of the shell thickness. Otherwise, we also simulated the sintering process of double CS NPs with equal size.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
Development of high loading Ag nanoparticle inks for inkjet printing and Ag nanowire dispersions for conducting and transparent coatings
No full textThe work presented in this thesis focuses on the synthesis of nanomaterials, formulation and
printing of Ag nanoparticle and nanowire inks for two distinct applications: a) inkjet printing
of Ag nanoparticle films on ceramic substrates with the aim of providing a smaller size of
printed feature at lower cost than that can be obtained with the conventionally used screen
printing, and b) Ag nanowires films prompted by the wide quest of electronics industry for
materials with increased flexibility, lower cost and higher transmittance to replace indium tin
oxide.
Ag nanoparticles with a size of 50 nm were successfully synthesized and dispersed in
aqueous medium. Two preparation routes were compared in order to distinguish the effects of
solvents treatment of particles and their influence on the suspension characteristics including
Ag loading, rheology, surface tension and later the electrical film properties. The co-polymer
Pluronic F127 was found to be an effective as a stabiliser leading to the formulation of high
silver loading in inks.
The processing and characterization of silver films was performed. The aim was to
reduce the number of layers in the silver nanoparticles film by increasing the thickness of a
single layer with the goal of obtaining a dense and conductive film. An increase in the Ag
loading, from 5 wt % to 45 wt % favoured the achievement of denser and thicker film with
one layer printing. Addition of SiO2 to the ink formula resulted in denser structure and better
adhesion of the printed track then the one without SiO2.
A new method for improving the morphology of inkjet printed tracks has been
proposed by printing the ink into the structured channels with predefined topography.
Silver nanowires were synthesised and dispersed in methanol with help of copolymer
F127. They were subsequently deposited on plastic and glass substrates forming conductive
and transparent films
Voltammetric Detection of Urea on an Ag-Modified Zeolite- Expanded Graphite-Epoxy Composite Electrode
No full textIn this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy) was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting electrolyte. This modified electrode exhibited moderate electrocatalytic effect towards urea oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus urea concentration was reached using square-wave voltammetry in the concentrations range of urea between 0.2 to 1.4 mM, with a relatively low limit of detection of 0.05 mM. A moderate enhancement of electroanalytical sensitivity for the determination of urea at EG-Ag-Z-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric/amperometric quantification.ChemE/Chemical EngineeringApplied Science
Ore mineralogy and trace element (re)distribution at the metamorphosed Lappberget Zn-Pb-Ag-(Cu-Au) deposit, Garpenberg, Sweden
No full textQualitative and quantitative mineralogical and textural investigations were undertaken for the different sulfide minerals in the 1.89 Ga Lappberget deposit, with a focus on sphalerite and pyrite. Three sphalerite types were identified and associated with: (1) main massive sulfide mineralization, (2) Fe-Mn skarn ore, and (3) Ag-rich fissure veins. Sphalerite-1 contained a relatively higher amount of trace elements (Fe, Co, Ge, Cu, Sn, and Au) but is lower in Mn/Fe, Ga, and Hg compared to sphalerite-2. Evidence of tectono-metamorphic modification of sulfides is observed throughout the deposit, such as the formation of growth twins and deformation twins in sulfides, the development of high-angled triple-point junctions in recrystallized pyrite and sphalerite, and the formation of â??ball oreâ?? or â??durchbewegungâ?? textures within mineralized shear zones. The recrystallization of pyrite and galena may have led to the re-distribution of fluid-mobile elements (As, Cu, Zn, Pb, Ag, and Au), some of which were deposited in discordant Ag-rich fissure veins peripheral to the main massive sulfide lenses. Trace element signatures of sulfides in Lappberget are compatible with the other metamorphosed and deformed, subseafloor volcanogenic carbonate replacement (SVALS)-type deposits in the Bergslagen mining district. © 2021 The Author(s)</p
Ore mineralogy and trace element (re)distribution at the metamorphosed Lappberget Zn-Pb-Ag-(Cu-Au) deposit, Garpenberg, Sweden
No full textQualitative and quantitative mineralogical and textural investigations were undertaken for the different sulfide minerals in the 1.89 Ga Lappberget deposit, with a focus on sphalerite and pyrite. Three sphalerite types were identified and associated with: (1) main massive sulfide mineralization, (2) Fe-Mn skarn ore, and (3) Ag-rich fissure veins. Sphalerite-1 contained a relatively higher amount of trace elements (Fe, Co, Ge, Cu, Sn, and Au) but is lower in Mn/Fe, Ga, and Hg compared to sphalerite-2. Evidence of tectono-metamorphic modification of sulfides is observed throughout the deposit, such as the formation of growth twins and deformation twins in sulfides, the development of high-angled triple-point junctions in recrystallized pyrite and sphalerite, and the formation of â??ball oreâ?? or â??durchbewegungâ?? textures within mineralized shear zones. The recrystallization of pyrite and galena may have led to the re-distribution of fluid-mobile elements (As, Cu, Zn, Pb, Ag, and Au), some of which were deposited in discordant Ag-rich fissure veins peripheral to the main massive sulfide lenses. Trace element signatures of sulfides in Lappberget are compatible with the other metamorphosed and deformed, subseafloor volcanogenic carbonate replacement (SVALS)-type deposits in the Bergslagen mining district. © 2021 The Author(s)</p
A comparative study in CCl4 reaction on Ag/Si(111) surfaces: PEEM and PES investigations
No full textA comparative study in CCl4 reaction on Ag/Si(111) surfaces: PEEM and PES investigations
Yunxi Yao, Qiang Fu, Xinhe Bao
State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P.R. China
We report a comparative study in the reactivity of bulk Ag(111), monolayer Ag film on Si(111), and Si(111)-77 surfaces via X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), photoemission electron microscopy (PEEM), and scanning tunneling microscopy (STM). The monolayer Ag film grown on Si(111), which is known as √3×√3-Ag-Si surface structure, was obtained by depositing one monolayer Ag on the Si(111)-77 surface at 550 K. The most simple halogen methane, CCl4, was chosen as the probe molecule to study the surface reactivity of the bulk Ag(111) surface, the monolayer Ag film, and the Si(111) surface. XPS and UPS data indicate that the monolayer Ag film presents unique reactivity to CCl4 in comparison to the other two surfaces. For the PEEM study, a dedicated sample consisting of bulk Ag particles supported on the monolayer Ag film was prepared as shown in the schematics in Fig. 1. In situ PEEM imaging of the surface reaction in presence of CCl4 shows a gradual change in the grey intensity from bright to totally dark on the Ag particles but little change on the √3×√3-Ag-Si surface. The grey intensity decrease is due to local work function increase from the dissociated Cl atoms. The experiments suggest that monolayer Ag is inert toward dissociation of CCl4 compared to the Ag(111) and Si(111) surface. It has proposed that the confinement of 5sp electron of Ag atoms in the √3×√3-Ag-Si surface, which is delocalized in the bulk Ag(111) surface, is decisive to the different reactivity.
Figure 1: (a) Schematic representation of the √3×√3-Ag-Si surface supported Ag islands; (b) PEEM image of the Ag islands/√3×√3-Ag-Si sample before CCl4 exposure. Field of view (FoV) is 27 μm; (c) PEEM image shows the same area in (b) but after 24 L (5.2×10-9 mbar × 6000 s) CCl4 exposure; (d) the work function change (ΔΦ) of the Ag(111) and √3×√3-Ag-Si surfaces when exposed to different amount of CCl4 at RT, measured from PES results.
References:
[1] Y.X. Yao, X. Liu, Q. Fu, W.X. Li, D.L. Tan, X.H. Bao, ChemPhysChem 2008, 9: 975-979.
*Corresponding author: Fax: +86-411-84694447, E-mail: [email protected], [email protected]
Nanospherical-lens lithographical Ag nanodisk arrays embedded in p-GaN for localized surface plasmon-enhanced blue light emitting diodes
No full textLarge-scale Ag nanodisks (NDs) arrays fabricated using nanospherical-lens lithography (NLL) are embedded in p-GaN layer of an InGaN/GaN light-emitting diode (LED) for generating localized surface plasmon (LSP) coupling with the radiating dipoles in the quantum-well (QWs). Based on the Ag NDs with the controlled surface coverage, LSP leads to the improved crystalline quality of regrowth p-GaN, increased photoluminescence (PL) intensity, reduced PL decay time, and enhanced output power of LED. Compared with the LED without Ag NDs, the optical output power at a current of 350 mA of the LSP-enhanced LEDs with Ag NDs having a distance of 20 and 35 nm to QWs is increased by 26.7% and 31.1%, respectively. The electrical characteristics and optical properties of LEDs with embedded Ag NPs are dependent on the distance of between Ag NPs and QWs region. The LED with Ag NDs array structure is also found to exhibit reduced emission divergence, compared to that without Ag NDs. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License
Microstructure Analysis Based on 3D reconstruction Model and Transient Thermal Impedance Measurement of Resin-reinforced Sintered Ag layer for High power RF device
No full textResin-reinforced silver (Ag) sintering material is an effective and highly reliable solution for power electronics packaging. The hybrid material’s process parameters strongly influence its microstructure and pose a significant challenge in estimating its effective properties as a thin interconnect layer. This research demonstrates a novel 3D reconstruction methodology for the microstructural investigation of the resin-reinforced Ag sintering material from OverMolded Plastic (OMP) packages. Based on the reconstructed models with different sintering parameters (temperature and time), the fraction of Ag and Resin volume distribution, the connectivity of silver particles, and the tortuosity factors were estimated. A 99% connectivity of sintered Ag particles was achieved with various sintering conditions, such as 200°C for 2 hours, 200°C for 4 hours, and 250°C for 2 hours. However, coarsening of Ag particles was promoted when sintered at 250°C. Increasing the sintering time at 200°C had insignificant changes. The estimated tortuosity factor also indicated that sintering at 250°C provides the shortest heat transport path between the semiconductor die and the package substrate. In order to quantify the microstructural findings, the OMP packages’ thermal performance with different sintering conditions (temperature, time, and interconnect thickness) was experimentally assessed. Although the experimental measurements were less sensitive to the effective interface thermal resistances’, the measurement results show a good correlation with the microstructural analysis. Sintering the Resin-reinforced Ag sintering material at higher temperatures (250°C) seems to improve the package thermal performance, and increasing the sintering time at 200°C has a negligible effect.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
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