Protected Silver Research Articles

Antioxidants are not protective silver bullet for songbird high blood sugar

Antioxidants are not protective silver bullet for songbird high blood sugar

Influence of long-term thermal treatment of magnetite nanoparticles on its physicochemical properties

In the presented paper, a long term thermal treatment at 50 °C was performed on four types of magnetite nanoparticles to observe if there is a transformation induced to other iron oxides. Such information is critical when hyperthermia application is foreseen due to different magnetic properties of Fe3O4, γ-Fe2O3 and α-Fe2O3. Nanoparticles were obtained by co-precipitation of iron (II) and (III) chlorides or by thermal decomposition of iron (III) acetylacetonate. Both types of nanoparticles were covered with a protective silver shell to increase their oxidative stability. The experiment was conducted in phases over the course of 28 days. Characterization of thermally treated nanoparticles was performed by transmission electron microscopy, x-ray diffraction, infrared spectroscopy and Mössbauer spectroscopy. According to the obtained results, nanoparticles synthesized by co-precipitation of iron chlorides are less thermally stable than those obtained by thermal decomposition. However, both types of nanoparticles do not oxidize to hematite even when exposed to long-term (up to 28 days) gentle (below 50 °C) heating.

Effects of stress, defects, and layer composition on the development of corrosion features on protected silver mirrors.

The long-term environmental durability of protected silver mirror coatings is influenced by numerous factors. Here, accelerated environmental exposure testing of model silver mirror coatings illuminated the effects of stress, defects, and layer composition on the extent and mechanisms of corrosion and degradation. Experiments to reduce stress in the highest-stress layers of the mirror coatings revealed that, while stress may affect the extent of corrosion, coating defects and the composition of the mirror layers have the largest influence on corrosion feature development and growth.

Plasmonic heating of protected silver nanowires for anti-frosting superhydrophobic coating

Atmospheric frosting and icing pose significant problems for critical and common-use infrastructures. Passive anti-frosting and anti-icing strategies that require no energy input have been actively sought, with no viable and permanent solutions known yet. Bioinspired superhydrophobic (SH) materials have been considered promising path to explore; however, the outcome has been less than compelling because of their low resistance to atmospheric humidity. In most cases, condensing water on an SH surface eventually leads to mechanical locking of ice instead of ice removal. Hybrid strategies involving some form of limited energy input are being increasingly considered, each with its own challenges. Here, we propose the application of plasmonic heating of silver nanowires (AgNWs) for remote frost removal, utilizing an SH hybrid passive-active system. This novel system comprises a durable nanocomposite covered with a hydrophobized mesh of AgNWs, protected against environmental degradation by a tin oxide (SnO2) shell. We demonstrate the frost removal ability at −10 °C and 30% RH, achieved by a combination of plasmonic heating of AgNWs with a non-sticking behavior of submicrometric droplets of molten frost on the SH surface. Heating was realized by illuminating the mesh with low-power blue laser light. Adjustment of the nanowire (NW) and shell dimensions allows the generation of surface plasmon resonance in illuminated NWs at a wavelength overlapping the emission maximum of the light used. In environmental stability tests, the nanostructures exhibited high atmospheric, mechanical, and thermal stability. The narrow-wavelength absorption of the structure in the blue light range and the reflective properties in the infrared range were designed to prevent protected surfaces from overheating in direct sunlight.

Optical, structural, and functional properties of highly reflective and stable iridium mirror coatings for infrared applications

Metallic coatings are essential for numerous optical systems due to their high and broadband reflectivity in the infrared spectral range. In contrast to well-established (protected) silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally, the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI, AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings differ due to their topography and microstructure.

Critical processing temperature for high-performance protected silver mirrors

Silver (Ag) mirrors for astronomical telescopes consist of multiple metallic and dielectric thin films. Furthermore, the topmost surface of such Ag mirrors needs to be covered by a protection coating. While the protection coating is often deposited at room temperature and the entire mirrors are also handled at room temperature, various thin film deposition techniques offer protection coatings with improved characteristics when carried out at elevated temperatures. Thus, in this work, high-performance Ag mirrors were designed and fabricated with a new benchmark. The resulting Ag mirrors were annealed (i.e., post-fabrication annealing) at various temperatures to investigate the viability of introducing thermal processes during and/or after fabrication in improving overall optical performance and durability of protected silver mirrors. In our experiments, Ag mirror samples were deposited by electron-beam evaporation and subsequently annealed at various temperatures in the range from 60 {\deg}C to 300 {\deg}C, and then the mirror samples underwent an environmental stress test at 80 {\deg}C and 80% humidity for 10 days. While all the mirror samples annealed below 200 {\deg}C showed negligible corrosion after undergoing the stress testing, those annealed below 160 {\deg}C presented spectral reflectivity comparable to or higher than that of as-deposited reference samples. In contrast, the mirror samples annealed above 200 {\deg}C exhibited significant degradation after the stress testing. The comprehensive analysis indicated that delamination and voids caused by the growth of Ag grains during the annealing are the primary mechanisms of the degradation.

Correlation of long-duration exposure and accelerated testing of protected silver mirrors.

The stability of two types of protected silver mirrors was studied by long-term exposure in a clean-room laboratory and mixed-flowing-gas (MFG) accelerated environmental test with two different gas concentrations. The two types of mirrors behaved very differently when exposed to the clean-room air for six years. The mirrors subjected to a reduced Battelle Class II MFG test protocol for 10 days exhibited similar corrosion mechanisms to those exposed to the clean-room air. With further testing of silver mirrors in both field exposures and MFG test conditions, it is feasible that the MFG-accelerated test method can be developed to quantitatively assess the durability of protected silver mirrors in ambient applications.

Development and growth of corrosion features on protected silver mirrors during accelerated environmental exposure.

Various layer schemes have been developed to protect thin film silver mirrors from tarnish and corrosion. However, the mechanisms by which these additional layers improve mirror durability are not fully understood. Accelerated environmental exposure testing of protected silver mirrors was used to investigate the effects of layer composition on the mechanisms of corrosion feature development and growth. Two model mirror coatings were analyzed in which the composition of the base layer below the silver and the adhesion layer above the silver were varied. Large circular corrosion features formed preferentially along the silver-chromium interfaces, regardless of where this interface was located within the layered structure of the mirror. The corrosion features originated at coating defects in the dielectric protection layer, and their growth was likely driven by the oxidation and chloridation of both silver and chromium at the Ag-Cr interfaces.

HiPIMS and DC Magnetron Sputter-Coated Silver Films for High-Temperature Durable Reflectors

High-temperature durable mirrors based on a protected silver sputter coating are attractive for secondary reflector applications in concentrated solar thermal power plants. In this paper, silver films are deposited by high-power impulse magnetron sputtering (HiPIMS) and standard direct current (DC) magnetron sputtering, either as exposed discretely deposited films or in-sequence-deposited thin film systems, where the silver is protected and embedded between adhesion and barrier layers. The unprotected silver films and equivalent protected silver thin film systems are compared and characterized as deposited and after 400 °C oven temperature exposure. The reflectance is measured and grazing incident X-ray diffraction (GIXRD) and scanning electron microscopy (SEM) pictures were taken. The HiPIMS silver film, sputtered with a peak current of 200 A and an approximately equivalent average power density to the DC magnetron sputtered silver, exhibits higher reflectance (and conductivity). Increasing the power density further, yields silver films with lower reflectance, correlating to a reduced grain size. In the protected silver film system, the reflectance does not improve, due to the presence of a less reflective top adhesion layer. The protected film system, with the 200 A HiPIMS, is, however, more durable at 400 °C than the DC magnetron sputtered equivalent.

Single Step Synthesis of Poly(o-Anisidine) Lignosulfonate Composite Protected Silver Nanoparticles and Study of Their Application on Reduction of Nitrophenol and Textile Dyes

Lignosulfonate doped poly(o-anisidine) and poly(o-anisidine)/lignosulfonate polymer composite protected silver nanoparticles (AgNPs) were synthesized by interfacial polymerization method by mixing of an equal molar ratio of o-anisidine and lignosulfonate using silver nitrite as oxidizing agent. The polymerization reaction was carried out under reflux condition at 80 °C for 3 hours. The resulting AgNPs nanocomposite was isolated and then characterized by using various instrument method including UV-visible spectroscopy, FT-IR, and FE-SEM analysis. The catalytic behaviour of the polymer protected silver nanoparticle was studied for the reduction of 4-nitrophenol (4-NP) and textile dyes like methylene blue (MB) and Congo Red. The reduction of 4-nitrophenol using AgNPs/poly(o-anisidine) nanocomposite reaction follow the pseudo first order kinetics and the resulting rate constant was found to be 10 min-1 for 4.0×10^-4 M concentration of 4-NP using 10 mg/L of catalyst. On the other hand, the catalytic behaviour of the nanocomposite was investigated toward the degradation of some of the textile dyes such as MB and Congo Red. The percentage of degradation of dye was monitored by UV-visible spectral studies and found to be superior to the other catalyst used for the degradation studies. The present method was employed for the effective removal of textile dyes and reduction of 4-nitrophenol with a minimum amount of catalyst.<div><br></div>

Degradation mechanism of protected ultrathin silver films and the effect of the seed layer

In this work, we characterize the oxidation and degradation of protected silver thin films through the Kirkendall effect. We then present a solution to reduce the degradation of silver films exposed to a reactive oxidizing environment. In particular, we study the growth of silver deposited by magnetron sputtering on glass substrates pre-coated with three different underlayers: SiO2, ZnO and a self-assembled monolayer of (3-mercaptopropyl)trimethoxysilane (MPTMS). The films are then covered with a 2-nm barrier titanium film and exposed to reactive oxygen plasma. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy reveal that the degradation process begins with the migration of silver through the top titanium barrier. We quantify the degradation by comparing the atomic content of silver present at the top of the degraded samples. We find that in the case of the ZnO and SiO2, a significantly higher amount of silver migrates through the top barrier and onto the surface, as compared to the MPTMS-treated surface. We attribute this difference to the chemisorption of silver atoms to the MPTMS layer.

Compact high‐sensitivity symmetrical integrated optical system for the detection of Raman scattering with dual channels

AbstractWe present here a compact symmetrical integrated optical system for the high‐sensitivity handheld Raman spectrometer. This symmetric optical system is of higher sensitivity of Raman spectrum detection by coupling collection optics to the spectrometer directly, reflecting excitation laser incident at 45° while efficiently passing the longer Raman‐shift wavelength with two long‐pass dichroic laser‐flat beam‐splitters placed in parallel. Three aspherical collecting lens with high‐numerical aperture were used to collect Raman scattering. Four protected silver plane mirrors, two right‐angle mirrors, and an aspherized achromatic focusing lens were used to focus Raman scattering into the slit on the collecting optical path. The Raman scattering light from the entrance slit were collimated to a blazed holographic reflective grating by an achromatic doublet lens, and the two diffraction lights with different orders were focused onto the two different surface of charge‐coupled device with two broadband dielectric coating concave mirrors, respectively. The coma and astigmatism of this optical system are decreased by optimizing the optical structure parameters. The finer Raman spectrum of samples can be obtained through the second order diffraction spectrum acquisition channel, whereas the first order diffraction channel covers almost all the Raman spectrum range. The tested spectrum of Benzoyl peroxide indicates that this symmetric integrated optical system with three collecting channels and double‐detecting channels has a higher sensitivity, higher signal‐to‐noise ratio, and finer Raman spectrum than the conventional portable Raman spectrometer with independent probe and single detection channel.

Development of micro-mirror slicer integral field unit for space-borne solar spectrographs

We present an innovative optical design for image slicer integral field unit (IFU) and a manufacturing method that overcomes optical limitations of metallic mirrors. Our IFU consists of a micro-mirror slicer of 45 arrayed, highly narrow, flat metallic mirrors and a pseudo-pupil-mirror array of off-axis conic aspheres forming three pseudo slits of re-arranged slicer images. A prototype IFU demonstrates that the final optical quality is sufficiently high for a visible light spectrograph. Each slicer micro-mirror is 1.58 mm long and 30 $$\upmu$$ m wide with surface roughness $$\le$$ 1 nm rms, and edge sharpness $$\le$$ 0.1 $$\upmu$$ m, etc. This IFU is small size and can be implemented in a multi-slit spectrograph without any moving mechanism and fore optics, in which one slit is real and the others are pseudo slits from the IFU. The IFU mirrors were deposited by a space-qualified, protected silver coating for high reflectivity in visible and near IR wavelength regions. These properties are well suitable for space-borne spectrograph such as the future Japanese solar space mission SOLAR-C. We present the optical design, performance of prototype IFU, and space qualification tests of the silver coating.

Stability, electronic structure, and optical properties of protected gold-doped silver Ag29-xAux (x = 0-5) nanoclusters.

In this work, we used density functional theory (DFT) and linear response time-dependent DFT (LR-TDDFT) to investigate the stability, electronic structure, and optical properties of Au-doped [Ag29-xAux(BDT)12(TPP)4]3- nanoclusters (BDT: 1,3-benzenedithiol; TPP triphenylphosphine) with x = 0-5. The aim of this work is to shed light on the most favorable doped structures by comparing our results with previously published experimental data. The calculated relative energies, ranging between 0.8 and 10 meV per atom, indicate that several doped Ag29-xAux nanoclusters are likely to co-exist at room temperature. However, only the Au-doped [Ag29-xAux(BDT)12(TPP)4]3- nanoclusters that have direct bonding between Au dopants and phosphines display an enhancement in the electronic transitions at ∼450 nm. This agrees with the main spectral absorption features that have been experimentally reported for the mixture of Au-doped silver Ag29-xAux nanoclusters. In addition, the formation of the Au-TPP bond could prevent cluster degradation starting from the detachment of the phosphine molecules, since the Au-TPP bond is stronger by ∼0.4 eV than the analogous Ag-TPP one. Thus, the results presented here show the important role of Au-TPP bonding in determining the stability and optical properties of thiolate/phosphine-protected Ag29-xAux nanoclusters.

Bigger Size Silver Nanoparticles Hamper Mother and Fetus Nutrition after Serial Ingestion of Bolotic Colloidal Nano Silver Stirring Solution through Oral Route: A Revolutionary Research Discovery in Teratogenicity &amp; Toxicity Field

In the field of household products like air conditioner, food protective wrapper silver foil, compressor, fabrics and washing machine manufacture, subscriber or consumer utilized engineered silver nanoparticles of multi bigger size (100 nm size range or more) demand has been extensively increased with increase of negative feedback while using. For the purpose to assess the effect of bigger size silver nano particles on body nutritional status, a serial oral application of silver nanoparticle colloidal stirring cool solution has been made upon pregnant Swiss Albino mice. On serial application (Daily once in morning 9 am continuously from 6 to 19 gestational ages) by repeated gavages during pregnancy pass through portal venous circulation towards liver after gastro intestinal tract absorption hampers mother nutrition by blocking intra hepatic billiary radical and also drastically affect fetal nutrition following same mechanism after crossing blood placental barrier due to gradual accumulation. The present research investigates whether orally induce colloidal silver nanoparticles (AgNps) reach after crossing mother mouse blood placental barrier and induce adverse effects in fetuses from treated group. Pregnant Swiss Albino female mouse from treated group are exposed during the first 13 days of gestation by serial oral bolotic application of bigger size silvernano colloid stirring cool solution at volume of 6, 12, 18, 24 mg/kg b.w. corresponds to individual group when compared with double distilled water vehicle control. Black ash colored bigger silver nanoparticles are identified scattered in maternal and fetal liver, upper GI tissues, placental and umbilical cord tissues of pregnant mother and fetuses after cesarean section and organ removal in gross , histological and TEM view. Particles are found in chronic depositative manner severely blocking portal triad of liver, IHBR and portovenous route. Transmission electron microscopy coupled with energy-dispersive spectroscopy confirmed the size range of particle silvernano from 71 to 1900 nm range. Serial oral ingestion of bigger size AgNps results in increased number of resorbed and malnutriated fetuses associated with reduced mother body and liver (sink & weak) weight and diet. Increased expression of particle accumulation is also detected in the placental cut section of treated groups. The acquired results indicates bigger size nanosilver are able to reach fetus after crossing the pregnant mouse blood placental barrier and portovenous circulation causing hamper of mother and fetus nutrition by obstruction of micro and macro channels. Henceforth as a conclusion, it is wise to take precaution with respect to oral exposure of bigger size silvernanoparticles during pregnancy.

Environmental durability of protected silver mirrors prepared by plasma beam sputtering.

Various overcoat layers have been developed to protect silver mirrors from tarnish and corrosion. However, the mechanisms by which these protective layers improve mirror durability are not fully understood. Mixed flowing gas exposure was used to investigate the corrosion behavior of plasma beam sputtered silver mirrors with different adhesion layer materials. A small amount of nickel in the adhesion layer had a significant impact on the silver-dielectric interface. Additionally, lateral transport of silver was found to be an important factor in the corrosion process. Better stability at all layer interfaces is suggested to improve mirror durability.

Oil-Soluble Silver-Organic Molecule for in Situ Deposition of Lubricious Metallic Silver at High Temperatures.

A major challenge in lubrication technology is to enhance lubricant performance at extreme temperatures that exceed conventional engine oil thermal degradation limits. Soft noble metals such as silver have low reactivity and shear strength, which make them ideal solid lubricants for wear protection and friction reduction between contacting surfaces at high temperatures. However, achieving adequate dispersion in engine lubricants and metallic silver deposition over predetermined temperatures ranges presents a significant chemical challenge. Here we report the synthesis, characterization, and tribological implementation of the trimeric silver pyrazolate complex, [Ag(3,5-dimethyl-4-n-hexyl-pyrazolate)]3 (1). This complex is oil-soluble and undergoes clean thermolysis at ∼310 °C to deposit lubricious, protective metallic silver particles on metal/metal oxide surfaces. Temperature-controlled tribometer tests show that greater than 1 wt % loading of 1 reduces wear by 60% in PAO4, a poly-α-olefin lubricant base fluid, and by 70% in a commercial fully formulated 15W40 motor oil (FF oil). This silver-organic complex also imparts sufficient friction reduction so that the tribological transition from oil as the primary lubricant through its thermal degradation, to 1 as the primary lubricant, is experimentally undetectable.

Rapid doubling of the critical current of YBa2Cu3O7−δ coated conductors for viable high-speed industrial processing

We demonstrate that 3.5-MeV oxygen irradiation can markedly enhance the in-field critical current of commercial second generation superconducting tapes with an exposure time of just 1 s per 0.8 cm2. The speed demonstrated here is now at the level required for an industrial reel-to-reel post-processing. The irradiation is made on production line samples through the protective silver coating and does not require any modification of the growth process. From TEM imaging, we identify small clusters as the main source of increased vortex pinning.

Conductance Degradation in HTS Coated Conductor Solder Joints

Solder joints between YBCO coated conductors and normal metal traces have been analysed as part of an effort to develop a robust HTS lead assembly for a spaceflight mission. Measurements included critical current and current transfer profiles. X-ray micrographs were used to verify proper solder flow and to determine the extent of voiding. SEM of cross-sections with EDS analysis was crucial in understanding the diffusion of the protective silver layer over the YBCO into the solder for different solder processes. The assembly must be stored for an extended period of time prior to final cool-down and operation. Measurements of the joint resistance over the course of months show a significant increase with time. Understanding the interface condition suggests an explanation for the change.

Description of particle induced damage on protected silver coatings.

In the visible to infrared spectral range, highly-reflective silver mirrors are applied in the manufacture of optical instruments such as telescopes. However, it is still difficult to combine high reflectivity and long-term stability of the protected silver coating. We show that the deposition of impervious protective layers is necessary but often not sufficient for long-term environmental stability. Hygroscopic air borne particles absorbed by the protections surface attract water molecules and form a solution. This solution first damages the protection, subsequently permeates the protection and finally damages the silver whereby the reflectivity is reduced. We demonstrate this particular damage mechanism with different experiments and describe this mechanism in detail.