This work is concerned with the characterisation of epitaxial (Hg,Mn)Te, and in particular the assessment of the structural and transport properties of the layers. Direct alloy growth (DAG) of (Hg,Mn)Te on buffered GaAs and unbuffered (Cd,Zn)Te substrates in a horizontal MOVPE reactor resulted in poor surface compositional and thickness uniformity. This was attributed to the differences in the pyrolysis rates of the Te and Mn precursors. Double crystal x-ray diffraction was used to determine accurately layer thickness, composition and quality. Analysis of the symmetric and asymmetric rocking curves revealed that for thickness over lµm (Hg,Mn)Te was almost 100% relaxed. A reduction in the dislocation density, as inferred from the x-ray rocking curve width, was observed with increasing layer thickness and was considered in terms of the Gay model. A sub-grain structure was seen using double crystal x-ray topography, where grain diameter decreased in a linear manner with inverse layer thickness. Triple axis x- ray diffraction revealed that tilts between the sub-grains were the primary cause of the rocking curve broadening. Hall and resistivity measurements were made in the temperature range 4K to 290K. The majority of the layers exhibited n-type behaviour, with carrier concentrations and mobilities dependent on layer thickness. Modelling of the temperature dependence of the carrier mobility was attempted for various lattice and impurity scattering mechanisms. Attempts were also made to explain the temperature dependence of the carrier concentration using a two band model and estimates for the bandgaps obtained from intrinsic Hall data. The interdiffused multilayer process (IMP) was then employed, resulting in layers with superior lateral compositional and thickness uniformities. Improved crystalline quality to that seen in comparable DAG layers was also obtained. The electron mobilities were higher in IMP lasers than incomparable DAG ones and analysis of the mobility data indicated that several scattering mechanisms were operative, including ionised and neutral impurity, optical phonon and piezoelectric (in Mn rich layers) scattering. Layers grown by IMP appeared to be more stable and changes in transport properties over a period of a few months were less pronounced than for comparable DAG layers.

This thesis describes the design, optimisation and shipboard deployment of a flow injection - chemiluminescence (FI-CL) technique for the determination of cobalt (Co) and manganese (Mn) in seawater. Chapter One presents an overview of the marine environment and the biogeochemistry of Co and Mn. Current analytical methods for the determination of Co and Mn in natural waters are also reviewed. Chapter Two reports reagent clean-up techniques and the synthesis of an 8- hydroxyquinoline resin used for in-line matrix elimination and preconcentration. The resin is also characterised in terms of its chelating ability for the transition metals and the earth alkaline metals. A new column design is also presented. Chapter Three details the optimisation of a FI-CL system for the determination of Co in seawater. The method described is based on a new chemistry whereby CL emission is produced by oxidation of pyrogallol with hydrogen peroxide in alkaline medium in the presence of CTAB and MeOH. Chapter Four details the optimisation of a FI-CL system for the determination of Mn in seawater. The method chosen involved the luminous oxidation of 7,7,8,8- tetracyanoquinodimethane (TCNQ) by dissolved O2. The weak chemiluminescence of TCNQ is effectively sensitised by Eosin Y in DDAB. In Chapter Five the application of the FI-CL method to the shipboard determination of Co in the western North Sea is presented together with results from the determination of Mn in the western North Sea samples after the cruise. Co and Mn profiles are shown for all the geographical area investigated. The data from an entire tidal cycle of the Humber are also shown. Chapter Six presents the results of an intercomparison exercise. Co and Mn have been measured with different analytical techniques: FI-CL, AdCSV, and ICP-MS. The method developed for Co has been adapted in order to measure the concentration of Co in samples from the Scheldt estuary with an integrated luminometer at the Universite Libre de Bruxelles.

No description available.

Graduation date: 1979

Thesis (M.Sc.) --University of Adelaide, 1951. / Typewr. copy.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1913. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed April 27, 2009) Includes bibliographical references (p. [ii]).

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed February 12, 2009)

Thesis (Ph. D.)--University of Illinois, 1915. / Vita.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Illinois, 1915. / Vita.