This is practice-based research about glass art, undertaken by an artist specialising in the lampworking technique. Over many centuries, lampworking has been widely used for scientific, industrial and craft purposes. In the early 1990s, there was a notable shift where traditional lampworking began merging with contemporary glass art, but there is still room for further development. The research focus is line-making through lampworking. Building upon Hoyt (1989), who determined the fundamental procedures in lampworking, this research identifies five operations relating to line-making: ‘bending’, ‘stretching’, ‘thickening’, ‘adding’ and ‘tooling’. Before this research, these techniques were already well practised in traditional lampwork training. However, they were recognised as only basics to construct larger pieces, and line-making itself did not gain real attention. Neither has the theoretical concept of making lines in glass been discussed enough. This research re-examines each of these operations and searches for dormant possibilities to exploit for artistic expression. The significance of glass lines is discussed in comparison to other line-making techniques and media in visual art. The taxonomy of lines advocated by Ingold (2007) is referred to as a guide for deeper exploration in this field. The investigation highlights the unique material feature of glass and contributes the idea of ’spatial traces’ and ‘projected lines’ to the discussion. A series of artworks is subsequently made to demonstrate and evaluate the research outcomes. The particular innovation generated by this research is the development of ‘calligraphic lampworking’, which is technically an extension of the ‘stretching’ operation. The act of stretching molten glass is observed to be comparable to ink calligraphy, in that they both leave a trace of movement. The distinctive difference is that the strokes of calligraphic lampworking are spatially liberated, whereas those of ink calligraphy are confined to the plane of a two-dimensional surface. The ‘multi-dimensionality’ of glass lines is also theoretically explored and discussed in terms of the glass’s clarity, reflections and shadows.

The electrical behaviour of a series of lithium silicate glasses has been characterised by the versatile a.c. impedance technique. The advantage of using a combination of complex plane and spectroscopic plots in the data analysis is shown. The compositional dependence of the conductivities of the phase separated glasses, which exhibit complex two-phase spinodal decomposition or nucleation and growth textures, is related to the volume fraction of the phases present in the conduction pathway and the tortuosity of the effective medium. The compositional dependence of the conductivities of homogeneous lithium silicate glasses is accounted for by postulating a glass structure composed of silicate anion clusters which are surrounded by a lithia-rich phase which constitutes the preferred conduction pathway. Annealing effects are also reported. The effect of surface roughness on the response of the electrode/electrolyte interface, a phenomenon originally reported by de Levie, and contact problems between the metal electrode and the glass electrolyte are discussed. Novel results regarding the effect of gold electrode recrystallisation on the a.c. response of glass electrolytes are reported. The a.c. impedance technique is shown to be a very useful, surface sensitive tool for monitoring interfacial phenomena such as atmospheric corrosion and surface ion-exchange. The technique is also successfully applied to studies of the mechanism of glass-ceramic formation, where the identification of surface crystallisation products and residual glass, by electrical measurement, is possible. Conclusive evidence for the presence of an effective medium conduction mechanism (percolation theory) in the inhomogeneous glass-ceramic, is given. The electrical data are corroborated by electron microscopy, x-ray diffractometry, energy dispersive x-ray analysis and Fourier Transform Infrared Spectroscopy.

New silver gallium thiophosphate glasses in the Ag<SUB>2</SUB>S-Ga<SUB>2</SUB>S<SUB>3</SUB>-'P<SUB>4</SUB>S<SUB>8</SUB>' system were studied employing a.c. impedance, Raman and IR spectroscopy. 'P<SUB>4</SUB>S<SUB>8</SUB>' does not exist and is used so that the compositions can be conventionally expressed in terms of network modifier and network formers. The glasses were in fact prepared from the elements. The trends in conductivity of other series of glasses were also studied including glasses with added AgI and mixed Ag-Na glasses. These glasses are interesting in that the phosphorus is formally in a IV+ oxidation state whereas other thiophosphate glasses previously reported in the literature contain phosphorus in a V+ oxidation state. Also, Raman spectroscopy has shown that these glasses contain hypothiodiphosphate units (P<SUB>2</SUB>S<SUB>6<SUP>4-</SUB></SUP>) which could be described as octahedral (the P-P occupies the place of the central atom). The phosphate and thiophosphate glasses studied thus far, have had structures based on meta(thio)phosphate chains of corner-sharing tetrahedra. Therefore these hypothiodiphosphate glasses are different in several respects to other thiophosphate glasses. Raman and IR studies of the 0.33Ag<SUB>2</SUB>S-0.33Ga<SUB>2</SUB>S<SUB>3</SUB>-0.33'P<SUB>4</SUB>S<SUB>8</SUB>' glass (or AgGaP<SUB>2</SUB>S<SUB>6</SUB> as it is more usually referred to in this thesis) suggest that the glass is composed of linear chains of -(Ga<SUB>1/2</SUB>P<SUB>2</SUB>S<SUB>6</SUB>Ga<SUB>1/2</SUB>)- units as proposed by Wibbelmann. Studies on the Ag<SUB>(1+x)</SUB>Ga<SUB>(1-x/3)</SUB>P<SUB>2</SUB>S<SUB>6</SUB> series lend weight to this model of the structure. The partial depolymerisation as Ga was replaced by Ag along the series could be followed by Raman spectroscopy. It was possible to relate the increase in conductivity (decrease in activation energy) along the series of changes in local structure. It was found that the compositional trends in activation energy can be explained in terms of the modified Anderson-Stuart model of Martin and Angell and in particular in terms of changes in the jump distance.

No description available.

Studies of semiconducting glasses have become of great interest in recent years because of their importance in the theory of solid state physics and in their applicability to electronic devices. Of these classes of materials the transition metal oxide glasses are much the most thoroughly studied. In these glasses the transition metal oxide e. g. V205-TiO2-MoO39 WO3, Cu0 is a major constituent i.e > 50 mol%. We start this work with a discussion about a critical review of the history, formation and modern theory of non-crystalline semiconductors in general and glassy state in particular. The aim of the experimental work in present study is to check the validity of the theories and models proposed so far to explain the origin and the nature of the charge carriers, structure, electrical and optical properties of some transition metal oxide glasses based on vanadium pentoxide. For this purpose series of binary V205-P205 glass samples containing 50 to 90 mol% V205 as well as ternary V2015-P205-Te02 glasses containing 60 mol% V2051 (40-x) mol% P205 and x mol% Te02 in which x varies from 5 to 35 were prepared by normal cooling from the melt. It was found that the glass forming region of the system under consideration is fairly large and in binary V205-P205 systems, glass with up to 95 moll V205 could be prepared. Density measurements indicate that in binary V205 - P205 glasses the density increases linearly with increasing V205 content and in ternary V205 - P205 - TeO2 systems density increases with increasing Te02 content. It was also found that the density of both systems are affected by annealing temperature. Electron spin resonance (E.S.R.) studies show that in vanadate glasses, the vanadium exists in more than one valency state mainly V5+ and V4+ of which V4+ is paramagnetic and detectable by E. S. R. This could be taken as some evidence of a hopping conduction mechanism in vanadate glasses and conduction is due to transfer of charge form V4+ to V5+ ions and this is discussed in the terms of small polaron. It is found that the conduction in these glasses is Ohmic up to a field of the order of 4x 105 Vcm-1 with an activation energy range from 0.31 to 0.48 e.V depending on composition and independent of temperatures in our range of temperature (above room temperature). Above this field conduction becomes non-Ohmic which is found to be due to lowering the potential barrier of the carriers at high electric field as was predicted by Poole and Frenkel. Memory switching is observed in thin blown film samples of both binary and ternary glass systems, which is associated with field-induced crystallization of a localized region and formation of conductive channel in the switched area due to self heating effect. In other words the conducting zone consists of VO2 crystals which possess more metal-like conductivity. Infra-red absorption spectra of these glasses revealed that some of the absorption bands of glasses and crystalline V205 are similar which is some evidence that the vanadium ions exists in six-fold co-ordination in disordered glassy systems as well as ordered crystalline V205. The fundamental absorption edge of these glasses occurs in the short wave length region of the visible and is dependent on composition, and the fundamental absorption arises form direct forbidden transitions and occurs at a photon energy of about 1.9-2.6 e.V depending on composition. The absorption edge in these glasses is found to be of the same order of magnitude as that in crystalline V205.

Binary series CoO-P205 and ternary series CoO-NiO-P205 glasses are prepared. The density, d.c. conductivity, highfield I-V characteristicsr memory switching actiong a.c. electrical conductivity, infra-red absorption and optical absorption edge of the glasses are presented. The historical background and the formation and theory of the glassy state are reviewed. Previous works on the electrical conductivity of phosphate glasses are reviewed in the framework of Mott's theory. In the binary glasses, the glass acquires a more compact structure with increased CoO content whereas for the ternary series the results show otherwise. A polaronic model is shown to be generally applicable to explaining the results of electrical conduction measurements. The pre-exponential factor containing the term exp (-2aR) arising from electron tunnelling should not be ignored; thus the theory of the small polaron hopping is in the non-adiabatic regime. The high-field ohmic behaviour is observed up to a field of about 3x 104 V-cm-l'. Apparentlyt the field dependence is a property of the bulk material. Thin films of glass with 30 Mol % CoO show memory switching phenomena. The results of a.c. measurements characterize hopping conduction as a dominant process in cobalt-phosphate glasses. Results of the infra-red spectra measured in the range 400 cm-1 to 4000 cm-1 show that the phosphate polyhedra dominate the structure of the glasses. Measurements of the optical gap in the binary series show decreasing values with increased CoO content. It is believed that the fundamental absorption arises from indirect transitions.

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No description available.

This thesis provides an investigation and review of homogeneous multilayer anti-reflective coatings (ARC) on glass. Recently, numerical optimization has become popular in optimizing the number of layers at a defined wavelength range and at angular incident angles. In this investigation, the design of the index profile is optimized for normal incident angle and angular incident angles by an evolutionary genetic algorithm. The anti-reflective coatings consist of multilayer porous silica or tin oxide nanoparticle films, which are fabricated by mixing 10nm silica nanoparticle or 10nm tin oxide nanoparticle colloidal solutions with varying amounts of 50nm polystyrene colloidal solutions, followed by spin coating on a glass substrate, and sintering at 400˚C for 40 minutes, which burns off the embedded polystyrene and renders a voided matrix. Experiments were carried out to produce ARCs based on well-known index profiles, and based on genetic algorithm optimization

This thesis provides an investigation and review of homogeneous multilayer anti-reflective coatings (ARC) on glass. Recently, numerical optimization has become popular in optimizing the number of layers at a defined wavelength range and at angular incident angles. In this investigation, the design of the index profile is optimized for normal incident angle and angular incident angles by an evolutionary genetic algorithm. The anti-reflective coatings consist of multilayer porous silica or tin oxide nanoparticle films, which are fabricated by mixing 10nm silica nanoparticle or 10nm tin oxide nanoparticle colloidal solutions with varying amounts of 50nm polystyrene colloidal solutions, followed by spin coating on a glass substrate, and sintering at 400˚C for 40 minutes, which burns off the embedded polystyrene and renders a voided matrix. Experiments were carried out to produce ARCs based on well-known index profiles, and based on genetic algorithm optimization