Pb Matrix Research Articles

Enhancing the oxygen evolution activity and stability of Pb anode in Mn2+-containing acidic solution by embedding MnCo2O4 particles

Due to the excellent activity and stability of MnCo2O4 toward the oxygen evolution reaction (OER) in acidic solution, a Pb–MnCo2O4 composite anode for zinc electrowinning was prepared by embedding dispersed MnCo2O4 particles into a Pb matrix in a powder metallurgy process. In this work, the phase structure, chemical composition, and morphology of the oxide layers formed on Pure-Pb and Pb–MnCo2O4 were analyzed by XRD, SEM, and EDS. Galvanostatic polorization, Tafel tests, and EIS measurements were performed to investigate the anodic potential variation and OER kinetics of the Pure-Pb and Pb–MnCo2O4 composite anodes. Compared with that on the Pure-Pb anode, the oxide layer on Pb–MnCo2O4 is thinner, more compact, and more stable in a 160 g L−1 H2SO4 solution containing 4 g L−1 Mn2+. Consequently, the Pb–MnCo2O4 composite anode exhibited a much lower anode slime production (8.7 mg) during 72 h of the simulated zinc electrowinning process. Despite the smaller surface area and lower PbO2 content of the oxide layer, the Pb–MnCo2O4 composite anode presented preferable OER kinetics with a lower OER charge transfer resistance (0.729 Ω cm2) and a smaller Tafel slope (90.74 mV dec−1), which contributed to a 70 mV reduction in the anodic potential compared with that of the Pure-Pb anode.

Structure and thermal stability of phosphochlorinated polybutadiene/carbon black composite synthesized via oxidative chlorophosphorylation reaction

The aim of the presented work was to obtain a new type of homogeneous composite based on an industrial polymer (polybutadiene, PB) and a well-known inexpensive filler (carbon black P-234, CB). For this purpose, the reaction of oxidative chlorophosphorylation (OxCh) was used. This makes it possible to introduce CB into the cross-linked structure of the modified polymer and ensure optimal distribution of the filler in it. The structure and thermal stability of the composite synthesized by the OxCh reaction were studied. Analysis of the composite by Fourier-transform infrared spectroscopy indicates a uniform distribution of carbon black in the network structure of the matrix and the physical interaction of the phases of the composite. Ultraviolet-visible spectrum data confirmed the improvement in light absorption in a wide range of the electromagnetic spectrum and the decrease in the optical band gap energy of the phosphochlorinated PB (PhPB) matrix with the addition of CB (Eg of PhPB = 3.25 eV; Eg of PhPB/CB composite = 2.28 eV). The influence of CB on the thermal stability of the PhPB matrix was studied using thermogravimetric and differential thermogravimetric analysis. After thermal analysis, the char yield for PhPB was 41 wt. %, and for PhPB/CB composite was 35.2 wt. %. Compared to PhPB, the increase in char yield, the decrease in maximum thermal decomposition temperature, and the high-integrated thermal decomposition temperature for the PhPB/CB composite show the improvement in the thermal stability of PhPB due to CB.

Unveiling the contribution of catalytic particles to the electrochemical performance of a Pb-dispersed particle composite anode for nonferrous metal electrowinning

Incorporating oxygen evolution catalytic particles into the Pb matrix via a powder mixing-pressing-sintering process is an effective strategy to develop efficient lead-dispersed particle (Pb-DP) composite anodes for nonferrous metal electrowinning. Catalytic particles are demonstrated to significantly reduce the anodic potential of Pb-DP anodes. However, the intrinsic contribution of catalytic particles to the electrochemical performance of Pb-DP anodes remains obscure. Herein, Pb-DP anodes with different dispersed particles (chemically inert Si or C, catalytic Co3O4 or MnCo2O4) were prepared. The anodic potential, microstructure and phase composition of the oxide layer, and oxygen evolution behavior of these Pb-DP anodes were investigated and compared with those of the Pure-Pb anode (prepared without dispersed particles). The results showed that compared with the Pure-Pb anode, Pb-Si and Pb-C anodes present similar microstructures and phase compositions of the oxide layer. However, they exhibit a larger Tafel slope for the oxygen evolution reaction (OER). Although the incorporation of catalytic particles (Co3O4 and MnCo2O4) reduced the thickness and specific surface area of the oxide layer and inhibited PbO2 growth, the presence of Co3O4 and MnCo2O4 significantly reduced the Tafel slope and charge transfer resistance (Rct) of the OER. Consequently, the anodic potentials of Pb-Co3O4 and Pb-MnCo2O4 are approximately 45 mV and 69 mV lower than that of Pure-Pb, respectively. It is demonstrated that the lower anodic potential of the Pb-Co3O4 and Pb-MnCo2O4 composite anodes originates from the catalytic activity of the dispersed particles rather than the physical effect of the dispersed particles.

Incorporating an Efficient Oxygen Evolution Catalyst of MnCo2O4.5 into a Pb Matrix as an Energy-Saving Anode for Metal Electrowinning

Based on the outstanding catalytic activity and stability of Mn-Co bimetallic oxides toward oxygen evolution in acidic solutions, MnCo2O4.5 was incorporated into a Pb matrix through a powder pressing-sintering process to obtain a Pb-MnCo2O4.5 composite anode. The results show that compared with the Pb anode that was made via the powder pressing-sintering process (PS-Pb), the oxide layer formed on the Pb-MnCo2O4.5 anode presented a higher flatness, compactness, and β-PbO2 concentration. Consequently, Pb-5.0MnCo2O4.5 presented a stable anodic potential of 1.235 V, approximately 170 mV lower than that of the PS-Pb anode. In the case of lower MnCo2O4.5 content (≤2.5%), the Pb-MnCo2O4.5 composite anode exhibited a smaller Tafel slope (70.39 ∼ 79.59 mV dec−1) and a lower charge transfer resistance (0.437 ∼ 0.676 Ω cm2). The fresh Pb-5.0MnCo2O4.5 composite anode showed a self-corrosion density of 0.25 mA cm−2, approximately 14.3% of that tested on the PS-Pb anode. However, Co2+ and Mn2+ were detected in the electrolyte during 72 h of electrowinning with the Pb-MnCo2O4.5 composite anode. In summary, the Pb-MnCo2O4.5 composite anode has the potential to reduce the energy consumption of the metal-electrowinning process. Nonetheless, it is necessary to evaluate the influence of dissolved Co2+ and Mn2+ on the cathodic process before commercial application.

Solid–liquid convertible hydrogel mediated by dual-functional cellulose nanofiber/Eu–dipicolinic acid/carbon dot complexes for high-precision sequential luminescence detection of cupric ion and oxytetracycline

A portable, sensitive, rapid, specific, and environment-friendly polyvinyl alcohol–borax (PB) hydrogel fluorescence probe was synthesized for the sequential sensing of Cu2+ and oxytetracycline (OTC) in wastewater. The aminated 2,2,6,6-tetramethylpiperidinooxy-oxidized cellulose nanofibers/europium complexes/carbon dot (ATOCN/Eu(DPA)3/CD) complex was added to the PB matrix. With the assistance of ATOCNs, the in-situ polymerized ATOCN/Eu(DPA)3/CD complexes were well-dispersed in the hydrogel and enhanced the mechanical properties of the hydrogel. The prepared hydrogel could be converted from solid to liquid by adjusting the water content to reduce the deviations caused by the solid probe detection. The probe not only induced evident fluorescence quenching and instantaneous response to Cu2+ at 430 nm and OTC at 617 nm but also exhibited a high selectivity to Cu2+ and OTC. The detection limits for Cu2+ and OTC were 0.031 and 0.019 mg L−1, respectively. Fluorescence recover was achieved by adding S2− for CuS precipitate formation and for the thermal decomposition of OTC. After repeatedly recovering the fluorescence for 10 times, the fluorescence intensity at 430 nm was restored to 79% of the original intensity and that at 617 nm was stored to 95%. The results show that hydrogels have remarkable potential applicability in detecting Cu2+ and OTC in wastewater.

Electrochemical performance of novel Pb alloys reinforced with Ni-coated fly ash microballoon composite foams in Lead Acid Battery

Novel Pb composite foams comprising hybrid gas pores and Ni-coated fly ash microballoons were produced by direct melt foaming method. Pb composite foams were designed to have a lower weight and larger surface area to be used in the Lead Acid Battery (LAB) as alternative to the traditional Pb grids, offering benefits in the transportation industry. The Ni-coated fly ash microballoons were added to Pb alloy melt to serve as thickening agent and pores, which were wholly enclosed within the microballoons, as well as reinforcements. The electrochemical performance of Pb grids used in traditional LAB and Pb composite foams produced in the present work was investigated for comparing purposes. The cured plates form positive and negative electrodes of Pb grid and Pb composite foams were characterized by X-ray diffraction to identify the different Pb compounds and phases. The morphology of the cured plate was found to contain flakes and dendritic structure. Zones were formed from a network of Pb particles in the negative electrode covered with PbSO4 crystals. The PbSO4 crystals exhibited miscellaneous morphology. The matrix of lead basic sulphate crystals was converted into aggregates of PbO2 particles in the positive electrode morphology, which maintained the form of the original substance. Cyclic voltammetry measurements (CV) were conducted in 3 M H2SO4 to study the anodic oxidation and cathodic reduction peaks of Pb, PbSO4 and PbO2. The galvanostatic polarization for oxidation and reduction steps was measured at different current densities. It revealed the benefit that the Pb matrix composite foam showed a longer period for oxidation of Pb into PbSO4. The composite foams exhibited a greater specific discharge electrical capacity than the Pb alloys used in traditional LAB.

Photovoltaic Performances of Dye-Sensitized Solar Cells Based on Modified Polybutadiene Matrix Electrolytes by Sol-Gel Process.

A new type of polymer matrix electrolyte based on modified polybutadiene (modified PB) was developed for dye-sensitized solar cells (DSSCs) to improve their stability. The modified PB was fabricated by cross-linking the reaction of polybutadiene with siloxane groups as a substitute sol-gel process. A DSSC device using the modified PB matrix electrolyte showed an open-circuit voltage of 0.64 V, a short-circuit current density of 15.00 mA/cm2, and a fill factor of 0.58 under photointensity of 100 mW/cm2 at AM 1.5, consequently leading to an overall solar energy conversion efficiency of 5.49%. The DSSC device using the modified PB matrix electrolyte improved the conductivity, and the charge transfer ability showed the outstanding stability of the device.

Migration Barrier Estimation of Carbon in Lead for Lead–Acid Battery Applications: A Density Functional Theory Approach

Recent efforts towards developing novel lead electrodes involving carbon and lead composites have shown potential for increasing the cycle life of lead–acid (LA) batteries used to store energy in various applications. In this study, first-principles calculations are used to examine the structural stability, defect formation energy, and migration barrier of C in Pb for LA batteries. Density functional theory with the GGA-PBE functional performed the best out of various functionals used for structural stability calculations. Furthermore, with the complete incorporation of C in the Pb matrix, the results show that C is energetically preferred to be at the octahedral interstitial (CiOcta) site in the FCC structure of Pb. Additionally, climbing-image nudged elastic band calculations show a minimum energy pathway for C diffusing from a stable octahedral site to the adjacent octahedral site assisted by a tetrahedral intermediate site. Therefore, the minimum energy pathway for C migration is envisioned to be CiOcta→ CiTetra→CiOcta, where the total energy barrier is observed to be ~90% and more than 100% lower than the CiTetra→CiTetra and CiOcta→CiOcta barriers, respectively.

Enhanced Mechanical Properties and Microstructure of Accumulative Roll-Bonded Co/Pb Nanocomposite.

Lead composites have been used as anodes in the electrowinning process to produce metals such as copper and zinc. Manufacturing stable lead anodes with appropriate mechanical and chemical properties is required to improve the performance of the electrowinning process. In this study, an accumulative roll bonding (ARB) method was used to fabricate a Co/Pb nanocomposite. Utilizing the ARB method can help us to achieve a uniform structure with enhanced mechanical properties via severe plastic deformation. The results showed that suitable tensile properties were obtained in Pb–0.5%Co–10pass samples. The tensile strength and strain of these samples were 2.51 times higher and 83.7% lower than that of as-cast pure Pb. They also showed creep resistance and hardness up to 1.8 and 2.5 times more than that of as-cast pure Pb. The ARB technique uniformly distributed Co particles in the Pb matrix. The enhanced strength of Pb samples was observed in the composite including grain sizes of less than 50 nm as a result of hindering the recovery phenomenon. The particle size of the Co distributed in the Pb matrix was 353 ± 259 nm. Compared to conventional methods, the ARB process improved the mechanical properties of Co/Pb composites and can open a new horizon to fabricating this composite in metal industries.

Microstructure and Mechanical Behavior of MnO2/Pb Nanocomposite

MnO2/Pb nanocomposite was produced by solid-state accumulative roll-bonding (ARB) technique. Composites with different amounts of MnO2 were synthesized with the highest probable ARB cycles. The mechanical properties of composites were studied by tensile, microhardness and shear punch tests. It was observed that yield stress, tensile stress and elongation were improved by increasing the ARB cycles. On the other hand, increasing the amount of MnO2 up to 0.5 wt.% improved the mechanical properties of the composites. Tensile tests results revealed that the maximum tensile strength could be achieved in the composite containing 0.5 wt.% MnO2 after 10 passes (up to 4.35 times higher than control sample, Pb-10 pass). In comparison with Pb-10 pass, the hardness of 0.5 wt.% MnO2/Pb nanocomposite was enhanced up to 7.5 times after 10 ARB passes. ARB process led to a proper distribution of MnO2 particles in Pb matrix with the mean size of less than 30 nm.

Nanocellulose-Mediated Electroconductive Self-Healing Hydrogels with High Strength, Plasticity, Viscoelasticity, Stretchability, and Biocompatibility toward Multifunctional Applications.

Conducting polymer hydrogels (CPHs) have emerged as a fascinating class of smart soft matters important for various advanced applications. However, achieving the synergistic characteristics of conductivity, self-healing ability, biocompatibility, viscoelasticity, and high mechanical performance still remains a critical challenge. Here, we develop for the first time a type of multifunctional hybrid CPHs based on a viscoelastic polyvinyl alcohol (PVA)-borax (PB) gel matrix and nanostructured CNFs-PPy (cellulose nanofibers-polypyrrole) complexes that synergizes the biotemplate role of CNFs and the conductive nature of PPy. The CNF-PPy complexes are synthesized through in situ oxidative polymerization of pyrrole on the surface of CNF templates, which are further well-dispersed into the PB matrix to synthesize homogeneous CNF-PPy/PB hybrid hydrogels. The CNF-PPy complexes not only tangle with PVA chains though hydrogen bonds, but also form reversibly cross-linked complexes with borate ions. The multi-complexation between each component leads to the formation of a hierarchical three-dimensional network. The CNF-PPy/PB-3 hydrogel prepared by 2.0 wt % of PVA, 0.4 wt % of borax, and CNF-PPy complexes with a mass ratio of 3.75/1 exhibits the highest viscoelasticity and mechanical strength. Because of a combined reinforcing and conductive network inside the hydrogel, its maximum storage modulus (∼0.1 MPa) and nominal compression stress (∼22 MPa) are 60 and 2240 times higher than those of pure CNF/PB hydrogel, respectively. The CNF-PPy/PB-3 electrode with a conductivity of 3.65 ± 0.08 S m-1 has a maximum specific capacitance of 236.9 F g-1, and its specific capacitance degradation is less than 14% after 1500 cycles. The CNF-PPy/PB hybrid hydrogels also demonstrate attractive characteristics, including high water content (∼94%), low density (∼1.2 g cm-3), excellent biocompatibility, plasticity, pH sensitivity, and rapid self-healing ability without additional external stimuli. Taken together, the combination of such unique properties endows the newly developed CPHs with potential applications in flexible bioelectronics and provides a practical platform to design multifunctional smart soft materials.

Synthesis of telechelic anthraquinone‐functionalized polybutadiene via ROMP and study of its photo‐oxidation and UV crosslinking behaviors

ABSTRACTTelechelic anthraquinone‐functionalized polybutadiene (AQ‐PB‐AQ) was synthesized by ring opening metathesis polymerization to achieve homogeneous dispersion of AQ groups in the polymer matrix. It was observed that the AQ end groups act as a sensitizing group resulting in photo‐induced crosslinking and oxidation reaction at the olefin groups in the PB. The process was confirmed by comparing the polymer's mass loss and Fourier transform infrared (FTIR) spectra with those of telechelic diacetoxy‐functionalized PB (AcO‐PB‐OAc) which did not show any difference before and after ultraviolet irradiation. Homogeneity of the AQ groups in PB matrix results in rapid crosslinking of PB in a short period of time (<4 min) while a simple blend of AQ methyl ester in AcO‐PB‐OAc matrix did not show such behavior. Photo‐oxidative reaction has concurrently occurred during the crosslinking reaction. Generation of OH, OOH, and carbonyl groups in the matrix during the photo‐oxidation was verified by FTIR, elemental analysis, and water contact angle measurements. A plausible mechanism for the process was proposed in which the photo‐sensitized AQ groups abstract hydrogen from the PB chain to yield reactive radical species, initiating oxidative crosslinking, and degradation of PB or reduction of AQ to hydroanthraquinone species. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1249–1258

Simulation of electrochemical processes during oxygen evolution on Pb-MnO2 composite electrodes

The geometric properties of Pb-MnO2 composite electrodes are studied, and a general formula is presented for the length of the triple phase boundary (TPB) on two dimensional (2D) composite electrodes using sphere packing and cutting simulations. The difference in the geometrical properties of 2D (or compact) and 3D (or porous) electrodes is discussed. It is found that the length of the TPB is the only reasonable property of a 2D electrode that follows a 1/r particle radius relationship. Subsequently, sphere packing cuts are used to derive a statistical electrode surface that is the basis for the earlier proposed simulations of different electrochemical mechanisms. It is shown that two of the proposed mechanisms (conductivity and a two-step-two-material kinetic mechanism) can explain the current increase at Pb-MnO2 anodes compared to standard lead anodes.The results show that although MnO2 has low conductivity, when combined with Pb as the metal matrix, the behaviour of the composite is not purely ohmic but is also affected by activation overpotentials, increasing the current density close to the TPB. Current density is inversely proportional to the radius of the catalyst particles, matching with earlier experimental results. Contrary to earlier SECM experiments, mass transport of sulphuric acid is not likely to have any influence, as confirmed with simulations.A hypothetical two-step-two-material mechanism with intermediate H2O2 that reacts on both the Pb matrix and MnO2 catalyst is studied. It was found that assuming quasi-reversible generation of H2O2 followed by its chemical decomposition on MnO2, results are obtained that agree with the experiments. If the quasi-reversible formation of H2O2 occurs near the peroxide decomposition catalyst, current increases, leading to an active TPB and to the current density that scales with 1/r. It is further emphasised that both the Pb matrix and MnO2 catalyst are necessary and their optimum ratio depends on the used current density. Yet, additional experimental evidence is needed to support the postulated mechanism.

Graphene nanosheets prepared by low-temperature exfoliation and reduction technique toward fabrication of high-performance poly(1-butene)/graphene films

Thermal exfoliation and reduction of graphene oxide (GO) were performed to prepare graphene nanosheets at 300 °C under the ambient atmosphere without any supplementary conditions. The microstructure and morphology of the resulting graphene nanosheets were characterized with scanning electron microscopy, transmission electric microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The composite films based on poly(1-butene) (PB) and graphene nanosheets were prepared successfully through solution blending and compression molding. The morphological investigation suggested that the graphene nanosheets with nanoscale thickness achieved a homogeneous dispersion in the PB matrix. The composite films exhibited a sharp transition from insulating state to the conducting one with a low percolation threshold, followed by a high electrical conductivity at graphene content higher than 1.6 vol %. The composite films also achieved high dielectric constant with low dielectric loss due to the effective electrical conductive path established by graphene nanosheets in a local range. Moreover, the mechanical evaluation demonstrated that a considerable reinforcement was achieved for the composite films due to the strong interfaces between the graphene nanosheets and PB matrix. The introduction of graphene nanosheets not only enhanced the nucleation capability and crystallinity of PB domain but also improved the thermal stability of the composite films. In addition, the composite films showed an increase in storage modulus and a decrease in loss factors due to the incorporation of graphene nanosheets.

Effect of glass fibre (GF) addition on microstructure and tensile property of GF/Pb composites fabricated by powder metallurgy

GF/Pb composites were fabricated by the method of powder metallurgy, and the density, microstructure and tensile property were characterized considering the size and content of glass fibre (GF). The results show that relative densities decrease with increasing GF fraction, and the 50 μm-GF reinforced specimens exhibit a better densification than the 300 μm-GF reinforced ones. The GF particles distribute quite uniformly in Pb matrix, and the composites fabricated at low sintering temperature (<200 °C) possess fine-grain microstructure. The addition of GF significantly improves the strength of the Pb composites, and the ultimate tensile strength of the Pb composite reinforced with the addition of 50 μm-0.5% GF (mass fraction) is about 30 MPa higher than that of GF-free sample. For all composites groups, increasing the reinforcement content from 0.5% to 2% (mass fraction) results in a decrease in both tensile strength and ductility.

One-pot methods for preparing polyaniline/Ag nanocomposites via oxidative polymerization of aniline

Ag-loaded polyaniline nanocomposites in the form of their fully oxidized pernigraniline bases (PB’s) are synthesized by one-pot chemical oxidation of aniline monomer using silver ion oxidant via two parallel methods. These two methods are compared with each other with respect to the content and size of the particle loaded. In method 1, leading to PB/Ag-1, ammonium peroxydisulfate (APS) and silver ion oxidants are used for two consecutive steps involving oxidative polymerization of aniline and oxidation of the emeraldine salt intermediate, respectively. In method 2, leading to PB/Ag-2, silver ions play the role of the oxidant in the polymerization step and inversely, APS oxidizes the intermediate salt obtained to the final nanocomposite. A significant enhancement in the content of the particle loaded could be resulted in method 2 (68.1 vs. 18.5 % by weight). Moreover, in method 2, the average size of the silver nanoparticles loaded into the PB matrix is found to be lesser than the method 1 (30 vs. 52 nm). TGA/DTG thermogram of PB/Ag-2 shows that the organic part of the nanocomposite (~30 wt%) undergoes a gradual thermo-degradation through a four-step pattern, mainly occurred at about 350 °C.

In-situ Electrochemical Synthesis Of Prussian Blue Composite With Gold Nanoparticles And Its Application In Hydrogen Peroxide Biosensor

This manuscript presents in-situ electrochemical synthesis of Prussian Blue-gold nanoparticles (PB- AuNPs) composite for application in hydrogen peroxide (H2O2) biosensor. The SEM image clearly showed the presence of AuNPs of size in range of 50 to 200 nm spread on PB matrix. UV-Visible spectra showed absorbance peak at 530 nm corresponding to AuNPs and a hump in 690-740 nm region for PB, confirming the synthesis of composite. The cyclic voltammetry (CV) showed the surface coverage of 3.65 x 10-9 mol/cm2 for pure PB film and 4.33 x 10-9 mol/cm2 for PB-AuNPs film, with diffusion coefficient of 1.19 x 10-9 cm2 /s, and 5.64 x 10-9 cm2 /s respectively. The film thickness is found to be 2.4 x 10-12 cm for PB and 2.9 x 10-12 cm for PB-AuNPs composite. The concentration of redox active centers (Fe+3/+2) is 3.5 moles/cm3 for ITO/PB and 4.1 moles/cm3 for ITO/PB-AuNPs respectively. The CV of ITO/PB showed one redox couple at 0.118 V and 0.215 V, whereas with ITO/PBAuNPs electrode, two sets of well-defined redox peaks; (i) 0.095 V & 0.135 V and (ii) 0.74 V & 0.78 V were obtained. The faradic current obtained with ITO/PB was 3.6 x 10-3 A and 7.3 x 10-3 A for ITO/PB-AuNPs composite film, respectively. The faradic current was almost double in presence of gold nanoparticles, as compared to pure PB. For H2O2 biosensor, the horse radish peroxidase (HRP) was immobilized on composite film and was used for H2O2 detection. The linearity was obtained from 10 to 90 nM, with sensitivity of 0.73µA/nM and the apparent Km value was 45 nM. The response time of reported biosensor is 20 sec and is stable for about three months.

Preparation of Au Nanoparticles and End‐Functionalized Poly(butadiene) Composites via Electrostatic Interaction

AbstractPolymer‐inorganic nanoparticle (NP) composites are prepared by immersing preformed end‐functionalized poly (butadiene) (PB) films, which have a lower glass transition temperature than room temperature, in an aqueous dispersion of Au NPs. Depending on the viscosity of the PB matrix, the Au NPs show different distributions in the end‐functionalized PB matrix. In the high viscosity matrix, the Au NPs are immobilized at the surface of the end‐functionalized PB, whereas in the low viscosity matrix, the Au NPs are incorporated into the matrix and are well dispersed. This incorporation of Au NPs occurs dynamically in three steps: (1) adsorption of the Au NPs on the surface of the PB matrix through electrostatic interactions; (2) stabilization of the Au NPs by the end functional groups of the PB molecules; (3) the diffusion of the Au NPs into the PB matrix because of the low viscosity of the matrix.

Electrorecrystallization of Metal Alloy

This work first reports the behavior of electrorecrystallization of metal alloy, solder in this study. The electrorecrystallization is the recrystallization of metal alloy induced by electrical current stressing without the need of prior treatment. The synchrotron radiation X-ray diffraction (XRD) in situ analysis shows that the crystal facets of the Pb matrix of 95Pb5Sn solder alloy gradually diminish during electrical current stressing. The XRD analysis incorporating with in situ synchrotron extended X-ray absorption for fine structure (EXAFS) reveals complete dissolution, giving rise to supersaturation, of the Sn-rich secondary phase upon current stressing. The supersaturation behavior was explained through the crystal relaxation of the Pb matrix induced by current stressing. The recrystallization gives rise to Sn nanorod. High resolution TEM analysis of the nanorod reveals the semi-coherent/incoherent interfaces and provides explanation for the formation of the Sn nanorod.

Evaluation of space charge effects in the second vacuum stage of a commercial inductively coupled plasma mass spectrometer by planar laser-induced fluorescence imaging

The effect of matrix on the formation and focusing of a Ca ion beam in the second vacuum stage of an inductively coupled plasma mass spectrometer has been evaluated with the use of planar laser induced fluorescence. A cross section of the beam was imaged near the entrance to the mass analyzer of a commercial instrument. Characteristics of the beam from a solution containing only the Ca analyte closely matched those predicted by simulation software. The individual addition of three matrix species, Mg, Cs, and Pb, had minor effect on beam shape. Cs and Pb both affected the beam trajectory. The most pronounced effect was with the Pb matrix, which caused an order-of-magnitude drop in the Ca signal intensity at the electron multiplier of the mass spectrometer. The loss in signal was due primarily to a shift in the direction and location of the Ca ion beam that caused it to miss the entrance into the mass analyzer.