Zn Wire Research Articles

Electrochemical Formation of RE-Zn (RE=Dy, Nd) Alloys in a Molten LiCl-KCl System

IntroductionWe proposed a new separation and recovery process for RE metals from Nd magnet scraps using molten salt electrolysis and an alloy diaphragm. The new separation and recovery process for RE metals was first applied to chloride melts, and the present study focused on the electrochemical formation of RE-Zn (RE=Dy, Nd) alloys in a molten LiCl-KCl system at 653 K. The separation of Dy was also investigated using a Zn electrode in a molten LiCl-KCl-DyCl3-NdCl3system.ExperimentalAll experiments were performed in LiCl-KCl eutectic melts under dry argon atmosphere at 653 K. DyCl3 or NdCl3 was added directly to these melts. The working electrodes were Mo and Zn wires for the investigation of electrochemical behavior. Rectangular shaped plates of Zn were used as the working electrodes. The reference electrode was a Ag+/Ag electrode. All the potentials given hereafter were referred to Li+/ Li electrode potential on a Mo wire. The counter electrode was a glassy carbon rod. The alloy samples were prepared by potentiostatic electrolysis. After the electrolysis, the samples were analyzed by XRD, SEM and ICP-AES.Results and discussionBefore the investigation of RE-Zn (RE=Dy, Nd) alloys formation, the electrochemical behavior of Li (I) was studied using a Zn or Mo wire as a working electrode in a molten LiCl-KCl system at 653 K. The scanning rate was set at 0.05 Vs-1. During the scan in the negative direction using a Mo electrode, a large cathodic current was observed at 0 V (vs. Li+/ Li). Since Mo does not form alloy with Li, the cathodic current corresponds to Li metal deposition. On the other hand, a cathodic current was observed from 0.60 V using a Zn electrode. Moreover, three large cathodic current peaks were observed. These two cathodic current peaks except for one cathodic current peak of 0 V correspond to the formation of Li-Zn alloys. When the potential scan direction was reversed at -0.05 V, two anodic peaks were observed. These anodic peaks suggest the Li dissolution from the different Li-Zn alloys.Taking into account the possibilities of the formation of various Dy-Zn alloys, the electrochemical behavior of Dy (III) was studied using a Zn or Mo wire as the working electrode in a molten LiCl-KCl-DyCl3 (0.50 mol%) system at 653 K. The scanning rate was set at 0.05 Vs-1. During the scan in the negative direction using a Mo electrode, a small cathodic current was observed at 0.50 V. Since Mo does not form alloy with Dy, the cathodic current corresponds to Dy metal deposition. Large and small cathodic current were observed from 0.60 and 1.10 V using a Zn electrode, respectively. Since these potential are more positive than that for Dy metal deposition (0.50 V), the cathodic current correspond to the formation of Dy-Zn alloys. When the potential scan direction was reversed at 0.50 V, three anodic peaks were observed. These anodic peaks suggest the Dy dissolution from the different Dy-Zn alloys.In order to investigate the formation potential of Dy-Zn alloys in detail, open-circuit potentiometry was carried out with a Zn electrode after depositing Dy metal by potentiostatic electrolysis at 0.50 V for 30 s in a molten LiCl-KCl-DyCl3(0.50 mol%) system at 723 K. There were three potential plateaus at (a) 0.57 V, (b) 0.95 V and (c) 1.20 V. The observed potential plateaus were considered to correspond to different coexisting Dy-Zn or Li-Zn phases, respectively. Based on the result of open-circuit potentiometry, an alloy sample was prepared by potentiostatic electrolysis at 0.70 V for 1 h. From the XRD pattern of the sample, the alloy phase was identified as DyZn3.

Sn–ZnO nanoneedles grown on Zn wire as a pointed field emitter and switching device

Sn–ZnO nanoneedles were grown by cathodic electrodeposition and an annealing process on Zn wire as a substrate. Scanning electron microscope studies showed the formation of ZnO nanoneedles. From the field emission studies, the field required to draw an emission current density of ~15.2mA/cm2 was observed at an applied field of ~0.14V/μm. In addition, field emission behavior of specimen grown on wire substrate demonstrates the applicability of Sn–ZnO as an electron current source with small optical size and switching device. The observed results suggest the suitability of this synthesis route for fabrication of pointed emitter.

Hybrid biobattery based on arylated carbon nanotubes and laccase

Single-walled carbon nanotubes (SWCNT) were covalently modified with anthracene and anthraquinone and used for the construction of cathodes for biocatalytic reduction of dioxygen. The nanotubes with aromatic groups casted onto the electrode increased the working surface of the electrode and enabled efficient direct electron transfer (DET) between the enzyme and the electrode. The aryl groups enter the hydrophobic pocket of the T1 center of laccase responsible for exchanging electrons with the substrate. Glassy carbon electrode covered with arylated SWCNT and coated with a layer of neutralized Nafion containing laccase was found to be a very efficient cathode in the hybrid battery. Zn wire covered with a Nafion film served as the anode. The cell parameters were determined: power density was 2mW/cm2 and the open circuit potential was 1.5V.

Cathodoluminescence of ZnO Crystals Prepared via Electric Current Heating Method Using Zn Wire

Zn wire was used as starting material in the fabrication of ZnO crystals in which a glass substrate was placed above the wire to grow ZnO crystals. The wire was heated by electric current in air. When the wire broke because of Joule heating, smoke arose from the wire and ZnO crystals were observed on the broken point, in the vicinity of the broken point, and on the glass substrate. The morphology and cathodoluminescence of the crystals were investigated. The crystals on the wire were 0.2–5 μm in size. The peak intensity ratio of ultraviolet (UV) emission to green emission increased with decreasing crystal size. The crystals on the substrate were tetrapod-like; the length and diameter of the tetrapod legs were 100–500 nm and 10–30 nm, respectively. The tetrapod-like nanocrystals produced only UV emissions.

Spatial and temporal variations in inhalable CuZnPb aerosols within the Mexico City pollution plume

We report on the CuPbZn content of PM10 and PM2.5 samples collected from three sites (urban T0, suburban T1 and rural T2) during the Mexico City MILAGRO campaign of March 2006. Daytime city centre concentrations of summation operator CuZnPb(PM10) were much higher (T0 > 450 ng m(-3)) than at the suburban site (T1 < 200 ng m(-3)). Rural site (T2) summation operator CuZnPb(PM10) concentrations exceeded 50 ng m(-3) when influenced by the megacity plume but dropped to 10 ng m(-3) during clean northerly winds. Nocturnal metal concentrations more than doubled at T0, as pollutants became trapped in the nightly inversion layer, but decreased at the rural site. Transient spikes in concentrations of different metals, e.g. a "copper event" at T0 (CuPM10 281 ng m(-3)) and "zinc event" at T1 (ZnPM10 1481 ng m(-3)) on the night of March 7-8, demonstrate how industrial pollution sources produce localised chemical inhomogeneities in the city atmosphere. Most metal aerosols are <2.5 microm and SEM study demonstrates the dominance of Fe, Ti, Ba, Cu, Pb and Zn (and lesser Sn, Mo, Sb, W, Ni, V, As, Bi) in metalliferous particles that have shapes including spherical condensates, efflorescent CuZnClS particles, cindery Zn, and Cu wire. Metal aerosol concentrations do not change in concert with PM10 mass, which is more influenced by wind resuspension than industrial emissions. Metalliferous particles can induce cell damage, and PM composition is probably more important than PM mass, with respect to negative health effects, so that better monitoring and control of industrial emissions would likely produce significant improvements in air quality.

ZnO thin films electrodeposited in propylene carbonate under a magnetic field

Electrochemical processing of ZnO films on fluorine-doped indium tin oxide (FTO/ITO) substrate was investigated in organic propylene carbonate electrolyte solutions containing Zn(NO3)2·6H2O. Much finer and more uniform morphologies of the ZnO films were obtained in comparison with those in aqueous electrolyte solutions. The effects of superimposing a magnetic field to the ZnO films were further examined. Superimposing a magnetic field considerably influenced the transient current density in the initial stage, especially in the mass transfer controlled region at −1.5 V vs Zn wire reference electrode. It also introduced substantially no drastic influence on the microstructure in spite of the appearance of considerably significant morphological variations.

Photoluminescence of zinc oxide crystals synthesized on zinc wire by electric current heating method

When a Zn wire was heated by electric current, ZnO whiskers grew on the wire surface. The average diameters of the whiskers grown under O 2, 20% O 2 and Ar atmospheres were 0.12, 0.17 and 0.4 μm, respectively. The well-known visible emission was observed from the whiskers grown under O 2 and 20% O 2 atmospheres. The whiskers grown under Ar atmosphere showed strong ultraviolet (UV) emission. X-ray diffraction measurements revealed that the crystalline quality of the whiskers increased with decreasing O 2 concentration in the growth atmosphere. It was found that residual O 2 of less than 10 ppm in Ar atmosphere is used for the synthesis of the whiskers with UV emission. Monitoring O 2 concentration during the electric current heating of Zn wire in Ar atmosphere was effective in estimating the yields of the whiskers.

Luminescence properties of Zn nanowires prepared by electrochemical etching

We have prepared samples of Zn wire structures by electrochemical anodization and measured their photoluminescence spectra at various temperatures. Scanning electron micrographs (SEM) were also taken on these samples. It was found that the dimension of the Zn wires has a definite influence on the photoluminescence (PL) spectra. Specifically, large wire dimensions exhibit a blue/violet luminescence. In addition to this blue/violet luminescence, nanowires of Zn about 20 nm in diameter exhibit a PL peak at 379 nm, which is the characteristic of ZnO. Low-temperature PL measurements on these Zn nanowires reveal three distinct excitonic emission peaks similar to high-quality ZnO. These results strongly suggest that high-quality ZnO nanowires can be formed by electrochemical etching of Zn.

Effects of zinc on the cytoskeletal proteins in the central nervous system of the rat

To test for in vivo zinc neurotoxicity on the cytoskeleton of neurotubules and intermediate filaments, Zn wires were implanted into the brains of adult Lewis rats for periods of 1-35 weeks. After 16 weeks of implant, some neurons showed bundles of intermediate filaments which were often localized in the perinuclear area. At the same time, occasional 200 nm tubular-like structures were seen in swollen dendrites. These structures were morphologically similar to Zn ion-induced aggregates of pure tubulin and structures found in ZnSO4-treated dorsal root ganglion organotypic cultures. The 200 nm structures in dendrites and the intermediate filaments in neurons increased in frequency with time. After 35 weeks of Zn wire implant, few microtubules could be found in the lesion. All the animals showed an astrocyte and glial filament proliferation with axoglial membrane specialization. Other wires studied: Pt, Ni, Co, Mg, demonstrate that Zn wires have a specific effect on cytoskeletal proteins in the CNS of the rat and many of the effects can be explained by an interaction between Zn and tubulin.