1,720,963 research outputs found
Electrodeposition and characterisation of nickel, germanium and tin thin films
No full textThe electrodeposition and characterisation of metals, Ni, Ni-B and Sn and a semi-conductor, Ge are the objectives of this study. Electrodeposition is an important metal surface coating technique as it can smoothly coat large and complex objects in a convenient and economically viable way. We are examining the microstructure of the films electrodeposited in this work using a variety of X-ray diffraction techniques, scanning electron microscopy, energy dispersive X-ray spectroscopy, wavelength dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy.Nickel coatings have wide applications in decorative and functional applications as hard, corrosion resistant surfaces. Boron is often incorporated into electrodeposited Ni using the standard Watt’s bath (nickel chloride/nickel sulphate/boric acid) and adding dimethylamine borane as the source of boron, the electrodepositions are achieved by chronopotentiometry.Germanium is an important semi-conductor, its widest application areas are optoelectronics and photonics. Ge films have been electrodeposited from tetrabutylammonium chlorogermanate [nBu4N][GeCl3] in tetrabutylammonium chloride [nBu4N]Cl dichloromethane solution, using chronoamperometry. The as-deposited Ge is amorphous. High temperature thermal annealing under anaerobic condition is applied to the films to crystallise.Tin is a soft, pliable and highly crystalline element with wide range of applications including decoration, electronic, and optical areas. Electrodeposition of tin is achieved from an electrolyte containing tetrabutylammonium chlorostannate [nBu4N][SnCl3] and tetrabutylammonium chloride [nBu4N]Cl in dichloromethane solution, using chronoamperometry. Flat tin films on Au sputtered on glass substrates, nanowire tin in phosphonate grafted anodic alumina and un-grafted AAO membranes were produced. Electrodepositions on Au substrate were obtained at various temperatures.Ni was electrodeposited in a highly crystalline form. The addition of B to the Ni matrix has reduced the degree of crystallinity and raised the amount of stress in the films. These effects were enhanced by increasing the amount of added B. Great influence on the preferred orientation of the Ni crystals was observed with the variations in the thickness and current density. In the Ge electrodeposition, modifications to the electrolyte composition and the substrate resulted in various morphologies and quality of adhesions in the Ge films, which was effective in the adhesion in the films after the annealing. Sn films were produced in a high crystalline form, electrodeposition at various temperature developed effects on the morphology and the texture of the electrodeposited Sn film. Characterisation on the Sn inside the anodic alumina templates indicates various diameter wires grown inside the membranes
Haloplumbate salts as reagents for the non-aqueous electrodeposition of lead
No full textCyclic voltammetry experiments on the Pb(II) salts, [PPh4][PbX3] (X = Cl, Br, I) in CH2Cl2 solution ([PPh4]X supporting electrolyte) at a Pt disk electrode show reproducible nucleation and stripping features consistent with reduction to elemental Pb. The reduction potential shifts to less cathodic from Cl (?0.40 V) ? Br (?0.27 V) ? I (?0.19 V vs. Ag/AgCl), in line with the Pb–X bond strengths decreasing. Potentiostatic electrodeposition using [PPh4][PbCl3] in CH2Cl2 leads to growth of a thin film of crystalline Pb onto planar TiN electrodes, confirmed by SEM, EDX and XRD analysis. Electrodeposition under similar conditions onto a planar Au electrode leads to deposition of elemental Pb, accompanied by some alloying at the substrate/film interface, with XRD analysis confirming the formation of AuPb2 and AuPb3. Transferring the [PPh4][PbCl3] reagent into supercritical CH2F2 (17.5 MPa and 360 K) containing [PPh4]Cl led to very limited solubility of the Pb reagent; using [NnBu4]Cl as a supporting electrolyte caused an increase in solubility, although still lower than in liquid CH2Cl2. Cyclic voltammetry experiments (Pt disk) using this electrolyte also show voltammetry consistent with Pb deposition, however the low solubility of the lead salt in scCH2F2 meant that electrodeposition onto a planar TiN substrate was not possible
Performance of nanocrystalline Ni3N as a negative electrode for sodium-ion batteries
No full textNickel nitride is synthesised by high temperature ammonolysis of nickel(II) hexamine and tris(ethylenediamine) salts. Its electrochemical characteristics are examined in half-cells vs. lithium and sodium. Samples with high surface area are found to have significant reversible charge storage capacity in sodium cells and hence to be a promising negative electrode material for sodium-ion batteries
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Electrodeposition of tin nanowires from a dichloromethane based electrolyte
No full textTin was electrodeposited from a dichloromethane-based electrolyte at ambient temperature into gold coated anodic alumina membranes with nanoscale pores. The tin nanowires are mainly <200> aligned, together with some <101> and <301> wires. Partial filling of the structure and a distribution of wire lengths was found. Grafting of the pores with hydrophobic surface groups was trialled as a means of modifying the deposition, however, it did not increase the proportion of pores in which wires grew. Under potentiostatic conditions the limited rates of nucleation and diffusion down the 1D pores control the growth of the nanowires
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