The main subject of the thesis is the investigation of palladium-iron alloy electrodeposition from aqueous solutions in general. Palladium-iron alloy deposits could be in principle a substitute for nickel or nickel-palladium deposits to avoid metal dermatitis. Nickel contact dermatitis is an especially sensitive allergy caused by decorative or functional use of nickel: it needs to be avoided in a number of applications. Electrochemical and chemical experiments have been carried out on several solutions with variable pH, salts and metal complexes to design a chemical and electrochemical stable electrolyte for palladium-iron alloy electrodeposition. Electrochemical measurements, physical and chemical analysis techniques, mechanical, optical, chemical and electrochemical measurements methods as well as different corrosion tests were used to describe the electrochemical processes and the properties of the palladium-iron deposits. Investigations have shown that from ammoniacal electrolytes electrodeposition in a wide range of composition is possible (pH = 7.5 - 10.5). Electrolyte consists of palladiurn as Pd(NH3)4CI2 and iron as iron(ill)-citrate. Composition of the deposited alloys depends mainly on the ratio of the metal ions in the electrolyte, while the effect of current density and electrolyte temperature is slight. Current efficiency depends on iron concentration in the electrolyte and is a maximum of ca. 85 %. Palladium-iron alloys with a higher content of palladium (>80.-%) show cracks because of the high internal stress (tensile stress) of those layers. Alloys with smaller content of palladium (<20 wt. -%) are less sensitive to cracking. Wear resistance and corrosion resistance of the palladium-iron alloys are similar or sometimes better to palladium, palladium-silver, palladium-cobalt or palladium-nickel deposits. Hardness of the palladium-iron layers increases with increasing iron content from 200 to 600 VHN. Contact resistance is low in the range of 0.5 to 1.5 mfl and barrier layer properties are excellent for gold and copper diffusion during services up to 160 degrees Celsius for 240 hours.

Electrochemical ellipsometry is employed to determine the real and imaginary parts of the refractive index and the thickness of thin films as functions of the potential applied to the electrode upon which the film is grown. The relatively recent advent of an analyser with no moving parts, the Stokesmeter, has removed previous time restraints and allows microsecond resolution. The Newcastle system is extremely novel, using a Stokesmeter, and thus being capable of 325 gs resolution, and also being electrochemically interfaced. The ellipsometric studies have concentrated on the growth and behaviour of a series of electroactive polymers derived from salicylaldehydes (Salens). [Ni(SaltMe)] and [Ni(SaIdMe)] were found to yield stable homogeneous films upon polymerisation, however while the behaviour during film growth was similar, marked differences were observed during potential cycling, poly[Ni(SaIdMe)] showing a marked decrease in thickness near the anodic limit not observed for poly[Ni(Saltme)], indicating that even minor changes to ligand structure well away from the site of polymerisation may have significant effects on the resulting film. The behaviour of poly[Ni(OMeSaltMe)] during polymerisation is more complicated; initially a homogeneous film is produced, however about half way through the growth process the film becomes inhomogeneous, and remains so during subsequent potential cycling. This behaviour was also observed for poly[Pd(OMeSalen)], indicating electron donating groups around the phenyl rings of the ligand have a profound effect on the nature of the polymer films, possibly far more so than the identity of the central metal.

<p>Selective serotonin re-uptake inhibitors (SSRIs) are a new class of antidepressants used mainly for the treatment of depression and other forms of related disorders. There are a number of side effects associated with these drugs which include loss of weight, sexual dysfunction, nervousness and nausea. A fast and reliable detection method such as biosensing for the determination of the SSRIs metabolic profile is therefore essential for the appropriate dosing of these drugs. Biosensors for the determination of the SSRIs biotransformation were prepared with cytochrome P450 (2D6) isoenzyme and poly (anilinonapthalene sulfonic acid) film electrochemically deposited on gold.</p>

Thesis (PhD)--University of South Australia, 2001.

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Nickel matte is a nickel &de concentrate produced by smelting. It consists mainly of two components: a nickel-copper alloy and heazlewoodite (Ni3S2); but also contains varying amounts of djurleite,Cu 1.96 S.There are several hydrometallurgical routes for processing nickel matte. The most recent of these involves an oxidative leach in acid chloride or sulfate solution. Nickel is subsequently recovered fiom the leach solution by electrowinning or by hydrogen reduction. In the work described in this thesis, various aspects of the acid leaching of nickel matte are investigated using mostly electrochemical methods. The first section concerns the use of copper(II) as an oxidant for the alloy component of nickel matte. In this cementation reaction, nickel goes into solution while copper is deposited on the dissolving metal swf8ce. The same reaction is important in removing traces of copper present in the nickel solution. Here nickel powder is added to the process liquor. A survey of the literature pertaining to the cementation of copper by nickel shows that there is considerable dispute as to the conditions under which cementation takes place. Evans' diagrams for the cementation reaction were constructed by superimposing the polarisation curves for the oxidation of nickel and the reduction of copper. It was found that cementation occurred provided that the two polarisation curves intersected in the region of active nickel dissolution. Outside this region, a copper deposit could not be seen. The second part of the thesis presents some investigations into the electrochemistry of nickel sulfides and nickel matte, and compares both chloride and sulfate media. Oxidation and dissolution rates of nickel matte powders using copper(I1) as an oxidant were also carried out. Dissolution was chemically controlled and so the rate was very dependent upon temperature and solution potential. Displacement of copper(II) from solution to form copper sulfide was also found to be important. In addition to the above studies, which relate directly to the oxidative leaching ofnickel matte, an investigation of the oxidation of HzS to sulfUr in acidic solution was carried out. S u k deposition was found to be strongly dependent on substrate and pH. Under some conditions, two types of sulfUr were deposited, with the more crystalline s u k being reduced at the more negative potential.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2007. / Includes bibliographical references.