Michael L. Norton

Thin-layer electrochemical studies of the underpotential deposition of cadmium and tellurium on polycrystalline Au, Pt and Cu electrodes

Abstract Thin-layer electrochemical studies of the underpotential deposition (UPD) of Cd and Te on polycrystalline Au, Pt, and Cu substrates have been performed. These studies were done in order to investigate the initial stages of the electrodeposition of CdTe. Tellurium deposition on Cu electrodes is very rapid at potentials between hydrogen evolution and Cu dissolution; as a result, the amount of electrodeposited Te cannot be suitably controlled with potential. Subsequent removal of Te on Cu also proved difficult by standard electrochemical cleaning procedures. Tellurium UPD and stripping on Pt occurred simultaneously with Pt oxide reduction and Pt oxidation, respectively. In addition, cadmium UPD on Pt is ill-defined, resulting in three peaks overlapping with the hydrogen wave voltammetry. It is presumed that the hydrogen waves are suppressed by the deposited Cd, although this is not definite. The most informative results were obtained with Au because of its broad double-layer window, which is free of complications from surface-specific faradaic reactions. Deposition of Te from TeO 2 solutions on Au was shown to require 3.9 ± 0.1 electrons per deposited Te. A substantial loss of electrodeposited Te was observed when the potential was cycled into the oxidation region on both the Au and Pt electrodes. Quantitation of the charge on Au indicated this loss was the result of oxidation of the Te(IV) to a Te(VI) compound which is difficult to reduce back to Te(IV) prior to hydrogen evolution on Au or Pt. At potentials between Au oxidation and Te UPD, the soluble Te species, HTeO + 2 , was shown to adsorb reversibly on the Au surface. In studies of the alternated deposition of Cd and Te, initially deposited Cd is displaced by Te at potentials positive of −0.35 V. Subsequent UPD of Cd on the Te-covered Au resulted in one Cd atom for each deposited Te.

Electrodeposition of Ba.6K.4BiO3

A novel, low temperature molten salt electrochemical technique has been used for the preparation of Ba.6K.4BiO3. The resulting crystalline material has been characterized by X-Ray diffraction, scanning electron microscopy and by energy dispersive X-ray analysis.

Preparation and characterization of thin films of copper(II) oxide by low temperature normal pressure metalorganic chemical vapor deposition

Abstract Using a volatile precursor, namely copper(II)hexafluoroacetylacetonate, it has been possible to prepare by the process of low temperature normal pressure metalorganic chemical vapor deposition, thin films of copper(II) oxide. These polycrystalline films were characterized by X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray analysis and by thermoelectric methods.

Electrodeposited Silver Arrays Fabricated Utilizing Self‐Assembled Alkanethiolate Monolayer Photoresist

Using self-assembled monolayers of the alkanethiol hexadecanethiol as a resist, ultraviolet photolithographic techniques were employed to fabricate arrays of electrodeposited silver on polycrystalline and single-crystal gold substrates. Growth of electrodeposited silver was used as a method of visualizing the photodefined domains. Domain definition was strikingly weaker on the single-crystal surface. This result is attributed to the increased thiolate and silver ion surface mobility expected on a single-crystal surface lacking significant defects or pinning sites.

Influence of water vapor on the morphology of Cu(II)O films produced by MOCVD

Abstract In the MOCVD production of oxide thin films, the use of oxygen saturated with water has been largely to reduce residual carbon and fluorine content. In this paper, the influence of water-saturated oxygen on the morphology of thin films of Cu(II)O produced by low temperature metalorganic chemical vapor deposition onto quartz, magnesium oxide and cubic zirconia substrates is described. The Cu(II)O films were characterized by scanning electron microscopy, energy dispersive X-ray microanalysis, optical transmission spectrophotometry and X-ray powder diffraction.

Application of Polypyrrole Film Substrates for Characterization of Metallic Electrodeposits by Transmission Electron Microscopy and Electron Diffraction

The utility of polypyrrole is demonstrated as a substrate for characterization of metallic electrodeposits by transmission electron microscopy and electron diffraction. Copper and nickel crystallites are electrodeposited onto a polypyrrole film at a potential negative of the film undoping potential at which counterions are expelled and the film becomes an insulator

Aspects of the crystal growth of the intergrowth tungsten bronzes

Abstract The crystal growth of a few of the members of the family of the rubidium intergrowth tungsten bronzes has been investigated as part of a program to study the compositionally induced metal to insulator transition in this bronze system. Progress in the study of this nonstoichiometric material has been made possible by successful growth of large single crystal samples. Application of vapor-assisted seeded crystal growth has led to an increase of the product crystal size by two orders of magnitude, from 0.1 mm on an edge to about 2 cm on an edge. Scanning electron microscopy has been used to characterize cracks, voids and intergrowths in this material. Transmission electron microscopy has been used to image the lattice of this quasi-two dimensional material in order to observe the frequency and amplitude of stacking defects.

Chemical vapor transport of Nb3Sn

Abstract A chemical vapor transport method has been used to produce free standing thick films of Nb 3 Sn utilizing TeCl 4 as a transport agent. The films have been characterized by scanning electron microscopy, energy dispersive X-ray analysis (EDX), X-ray diffraction and by magnetic susceptibility. The dense films display large crystallite size, are stoichiometric by EDX and XRD, and are shown by magnetic studies to exhibit a sharp superconducting transition.