The work described in this thesis is a study of imperfections in high purity, low dislocation content synthetic quartz single crystals which are grown on a commercial scale by the General Electric Company. Hydrogen and metal ion impurities in quartz were studied using low temperature transmission Fourier Transform Infrared Spectroscopy, (FTIR). Incorporation of impurities in quartz was investigated using crystals which were doped with Al, Fe, Cr, Co, Ti, P, Cu and K. Orientation of hydroxyl impurities was determined using polarised infrared spectroscopy. Deuterated quartz crystals were grown and studied as analogues to high purity crystals. X-ray diffraction topography was used to evaluate crystal quality and to perform a study of quartz which had been treated by electrodiffusion, or sweeping. Crystal lattice strain and sweeping damage was studied using double crystal topography at the Synchrotron Radiation Source, (SRS), at the Daresbury Laboratory. Metal ion impurities were sh own to incorporate interstitially into quartz crystals. The only exceptions were aluminium and iron, which incorporated substitutionally. All the impurities studied introduced hydrogen impurities such as hydroxyl ions and water molecules into quartz. A relationship between impurity concentration and hydrogen content was clearly indicated. The 3200 cm-1 broad absorption band characteristic of impure and fast grown synthetic quartz was strongly implicated as being due to interstitially incorporated water molecules. The major hydrogen impurities in quartz were sodium hydroxide molecules which were preferentially aligned along the X, Y and Z growth axes. Hydroxyl ions were not incorporated directly from the growth solution. Sweeping was shown to induce the formation of a negative space charge in treated quartz which gave rise to inhomogeneous lattice strain. The strain was gradually relieved upon prolonged exposure to x-rays. A mechanism for the production and relief of lattice strain has been proposed. Sweeping produced surface damage on mechanically polished crystals but not on those treated by chemical polishing using hydrofluoric acid. No further detrimental effects of sweeping were observed. Double crystal topographic studies revealed two possible bulk defects in Quartz. The first of these was a previously unreported planar defect parallel to the X-Y plane of quartz. The second was possibly a planar defect associated with the cellular growth cells in the (00.1) growth sector of quartz. The validity of these observations was put in doubt by the possibility of defect projection from the silicon monochromator which had been used in double crystal studies.

In the medical world the precise identification of a disease can take longer than it is safe to wait to start treatment so there is a need for faster and more precise biosensors. Bond Rupture is a new sensor technique that maybe able to improve disease detection. It does this by inducing bonds to rupture from the surface, and also measuring the point at which this rupture occurs this enables the forces to be measured on the surface. Specifically, this project has focused on the application of Bond Rupture to detecting antigens when bound to a surface using their specific antibodies, and the idea that the rupture force of these antigens can also be measured. The sensor that this project is based around is the Quartz Crystal Microbalance (QCM), which oscillates horizontally when a voltage is applied, and can also be used to measure mass change on its surface via change in resonant frequency. The aim of this project was to investigate possible Bond Rupture detection methods and techniques and has involved the development of a high speed digital electronics system, for the purposes of inducing and detecting Bond Rupture. This has involved the development of a FPGA based high speed transceiver board which is controlled by a Digital Signal Processor (DSP), as well as the development of various graphical user interfaces for end user interaction. Bond rupture testing was carried out by rupturing beads from the surface of a QCM in an experiment taking as little as 20 seconds. The Bond Rupture effect has been observed via the high accuracy measurement of the frequency change while inducing Bond Rupture on the sensor, proving that the Bond Rupture effect indeed exists. The research performed is believed to be a world first in terms of the method used and accuracy acquired.

No description available.

A dissertation submitted in fulfilment of the requirements for the Degree of Master of Science in Archaeology to the Faculty of Science, University of Witwatersrand, 2019 / The study examines the technology of crystal quartz pieces from Pomongwe Cave (PMG), Matopos, and south-western Zimbabwe. It focuses on the Middle and Later Stone Age (MSA and LSA) assemblages, which were excavated in the early 1960s by C. K Cooke and is housed at the Zimbabwe Museum of Human Sciences (ZMHS) in Harare. The research employs the chaîne opératoire approach to the study of crystal quartz technology, which follows all the stages of lithic production from the sourcing of the raw material through exploitation, use and discard patterns. It seeks to understand how the hunter-gatherers at Pomongwe (PMG hereafter) exploited this material and how they adapted their technologies to suit the physical and mechanical properties of crystal quartz through time at the site. On a broader scale, the study contributes to our understanding of the development of Modern Human Behaviours (MHBs). The results of the study show that the sourcing of the crystals was mainly from a secondary context throughout the MSA and LSA sequence. The presence and distribution of the material also varied throughout the MSA and LSA sequence, suggesting that the raw material was more prominent with the inhabitants during certain periods than others. The results through classification also show that not all collected crystals were exploited for lithic production, which raises questions as to why they were collected. The cores and blanks show that the crystals were mainly opened from the pyramid and exploited going towards the base of the crystal. The most notable change in the exploitation of crystal quartz throughout the MSA and LSA sequence at PMG is that of the reduction in the sizes of the blanks going towards the LSA. / TL (2020)

No description available.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xi, 204 p. : ill. (some col.) Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references.

The electrochemical quartz crystal microbalance (EQCM) has been proven an effective mean of monitoring up to nano-scale mass changes related to electrode potential variations at its surface. The principles of operation are based on the converse piezoelectric response of quartz crystals to mass variations on the crystal surface. In this work, principles and operations of the EQCM and piezo-electrodes are discussed. A conductive oxide, ruthenium oxide (RuO2) is a promising material to be used as a diffusion barrier for metal interconnects. Characterization of copper underpotential deposition (UPD) on ruthenium and RuO2 electrodes by means of electrochemical methods and other spectroscopic methods is presented. Copper electrodeposition in platinum and ruthenium substrates is investigated at pH values higher than zero. In pH=5 solutions, the rise in local pH caused by the reduction of oxygen leads to the formation of a precipitate, characterized as posnjakite or basic copper sulfate by means of X-ray electron spectroscopy and X-ray diffraction. The mechanism of formation is studied by means of the EQCM, presenting this technique as a powerful in-situ sensing device.

<p>In order to develop blood biocompatible materials a heparin surface and a phosphorylcholine (PC) functionalized polymer surface were characterized using photoelectron spectroscopy (PES). The formation of the heparin surface was studied by quartz crystal microbalance with dissipation monitoring (QCM-D). This heparin surface consists of heparin conjugates deposited on a conditioning layer, applied once or twice. The PC functionalized polymer, poly(trimethylene carbonate), was linked to a silicon substrate through 3-amino- propyltrimethoxysilane (APTMS), also studied using PES. </p><p>Synchrotron radiation based PES showed that the thicker heparin film resulted in complete coverage of the substrate, while the thinner did not. This could explain the difference in blood biocompatibility between the two films, as observed by others. It was also found that the heparin chains bend down towards the substrate (under vacuum). </p><p>For the thinner heparin film the modifications, resulting from extensive irradiation of the sample, were studied with synchrotron radiation based PES. This was done at a pressure of about 10^-7 mbar and in 0.5 mbar water vapor. It was found that the modification is slower under water vapor than at low pressures and that the damaged film incorporates water upon exposure.</p><p>The heparin coating was found to be stable and wear resistant enough to still be present on artificial heart valves after three weeks testing in circulating plasma. It then had about the same antithrombin uptake as a non-tested surface. The film was, however, partly destroyed by the durability test and plasma proteins were deposited. </p><p>The PC functionalized, APTMS linked polymer was found to be much shorter than could be expected from random reactions. One plausible explanation is an interaction between the PC group and the silane surface, favoring aminolysis close to the PC group. This is consistent with our finding that the PC group bends down towards the surface.</p>