A variety of nanostructures of tin (IV) oxide (TO) are synthesized using two fabrication methods: a solution spin-coating method followed by post-annealing in an oxygen flow and a newly developed catalyst-assisted pulsed laser deposition (PLD) technique. The spin-coating method is used to fabricate granular TO films with monodisperse, stable, ultra-small nanocrystallites (4-5 nm in size), the size of which is found to increase exponentially with post-anneal above 500??C. These nanocrystalline films are conductive and highly transparent, and their bandgap shows broadening due to a high carrier concentration. Their resistivity behavior as a function of temperature in the 50-280 K range can be explained by a two-medium transport model, i.e. transport through the crystalline grains and across the grain boundaries, and through the charge-depletion layer, where a potential barrier is found for transport across the grain boundaries. Electronic transport in these films follows a 3D-variable range hopping model, which reveals an increase in the localization length of carriers with increasing the TAnneal above the onset of exponential growth at TAnneal= 500??C. By homogenously doping Eu3+ in these nanocrystalline films up to a high doping level of ~ 8%, optical luminescence and magnetic orderings can be introduced into these nanocrystalline TO films. Both characteristic Eu3+ emission and defect-related TO emissions are observed in the otherwise transparent TO films upon UV-excitation. In spite of the non-magnetic nature of Eu3+ ions, magnetic orderings appear in the highly doped TO films below 50 K upon the emergence of Eu2Sn2O7 phase. In the second part of this work, we employ a layer of gold nanoislands with controlled sizes (10-50 nm) as catalysts for pulsed laser deposition of TO nanostructures. Highly crystalline TO nanobricks, cuboid nanoparticles, nanowires and nanobelts are obtained for the first time through vapour-solid or vapour-liquid-solid (VLS) mechanisms. Of particular interest are the micron long one-dimensional (1D) nanowires and nanobelts, with the smallest square and rectangular cross-sections, respectively, ever reported. These single-crystalline nanostructures are obtained at relatively low temperatures of 600??C, for nanowires, and 500??C, for nanobelts, and their cross-sectional sizes can be easily controlled by the size of the gold nanoislands. The nanobelts are found to grow along the [100] and [101] axes, while the nanowires appear to grow along the [100] axis. The growth evolution of the nanobelts are also investigated in detail revealing their VLS growth mode and their single-crystalline structure throughout the growth, which opens the prospect of controlling their growth axis and consequently their side-surface planes by pinning the base to the substrate at the desired crystalline orientation. Together, the two fabrication methods developed in the present work offer facile approaches to growing two scientifically and technologically important classes of TO nanostructures, i.e., nanocrystalline film and 1D nanostructures. Thorough characterization of the resulted nanostructured materials using advanced microscopic, spectroscopic and other techniques, including Helium Ion Microscopy, has been provided. Modification of structure, morphology and physical properties of these functional nanostructured materials are also illustrated by controlling the growth parameters and by (Eu-)doping, which pave the way for introducing new properties for applications in chemical sensing, (opto)electronics and displays.

Nuo 1926-ųjų metų, kai pirmą kartą buvo ištirta preliminari natūralių silikatinių mineralų, turinčių kubinę kristalinę gardelę, struktūra, granatų šeimai priskiriami junginiai tapo viena labiausiai tyrinėjamų medžiagų grupių. Granatai, kuriuose yra pereinamųjų metalų bei retųjų žemių metalų, pasižymi ypatingu technologiniu pritaikymu. Kaip šviečiančios medžiagos jie naudojami kietafaziuose lazeriuose, televizorių ekranuose ar dioduose. Europiu arba chromu legiruoti junginiai galėtų būti pritaikyti optiniam vaizdavimui medicinoje, kas iki šiol nebuvo daryta. Galimybė pagerinti granatų optines ir mechanines savybes bei naujos pritaikymo sritys suteikia stiprią motyvaciją tyrinėjimams. Pagrindinis disertacijos tikslas buvo naujų mišrių metalų granatų sintezė bei jų optinių savybių tyrimas. Taip pat siekta ištirti europį supančios aplinkos įtaką jo liuminescencinėms savybėms tiek milteliuose, tiek kristaluose. Milteliai buvo sintetinti zolių-gelių arba kietafazės reakcijos metodu. Kristalai auginti keliaujančio lydalo slankioje zonoje būdu. Medžiagų faziniai virsmai tirti Rentgeno spindulių difrakcijos metodu. Neutronų difrakcijos duomenys bei Rietveldo tikslinimas buvo panaudoti granatų struktūrinei analizei. Junginių optinės savybės įvertintos išmatavus atspindžio, sužadinimo ir emisijos spektrus. / Since 1926 when the preliminary structure of natural silicate minerals having cubic structure was determined, the family of garnets became one of the most extensively studied group of compounds. Garnets containing transition metals and rare-earths carry many important technological uses as magnetic materials, as phosphor materials employed in solid state lasers, television screens and light-emitting diodes, as computer memories, as near UV and near IR radiation up/down-converting compounds in Si solar cells and in other devices as microwave optical elements. The europium or chromium doped garnets also could be applied in the new field as optical imaging. The improvements in mechanical and optical properties, the new areas of applications provide a strong motivation for studying garnets in general. To synthesize and to characterize new mixed-metal garnets was the main aim of the present thesis. The investigation of the dependence of europium optical properties on the local environment in different garnets was also in the field of interest. Therefore, powders of the new mixed-metal garnets were synthesized by sol-gel route, while traveling solvent floating zone method was used for crystal growth. X-ray diffraction was used for phase identification. The neutrons diffractions and Rietveld refinement gave information of the crystal structure. Finally, reflection, excitation and emission spectra were recorded for the investigation of the optical properties.

Since 1926 when the preliminary structure of natural silicate minerals having cubic structure was determined, the family of garnets became one of the most extensively studied group of compounds. Garnets containing transition metals and rare-earths carry many important technological uses as magnetic materials, as phosphor materials employed in solid state lasers, television screens and light-emitting diodes, as computer memories, as near UV and near IR radiation up/down-converting compounds in Si solar cells and in other devices as microwave optical elements. The europium or chromium doped garnets also could be applied in the new field as optical imaging. The improvements in mechanical and optical properties, the new areas of applications provide a strong motivation for studying garnets in general. To synthesize and to characterize new mixed-metal garnets was the main aim of the present thesis. The investigation of the dependence of europium optical properties on the local environment in different garnets was also in the field of interest. Therefore, powders of the new mixed-metal garnets were synthesized by sol-gel route, while traveling solvent floating zone method was used for crystal growth. X-ray diffraction was used for phase identification. The neutrons diffractions and Rietveld refinement gave information of the crystal structure. Finally, reflection, excitation and emission spectra were recorded for the investigation of the optical properties. / Nuo 1926-ųjų metų, kai pirmą kartą buvo ištirta preliminari natūralių silikatinių mineralų, turinčių kubinę kristalinę gardelę, struktūra, granatų šeimai priskiriami junginiai tapo viena labiausiai tyrinėjamų medžiagų grupių. Granatai, kuriuose yra pereinamųjų metalų bei retųjų žemių metalų, pasižymi ypatingu technologiniu pritaikymu. Kaip šviečiančios medžiagos jie naudojami kietafaziuose lazeriuose, televizorių ekranuose ar dioduose. Europiu arba chromu legiruoti junginiai galėtų būti pritaikyti optiniam vaizdavimui medicinoje, kas iki šiol nebuvo daryta. Galimybė pagerinti granatų optines ir mechanines savybes bei naujos pritaikymo sritys suteikia stiprią motyvaciją tyrinėjimams. Pagrindinis disertacijos tikslas buvo naujų mišrių metalų granatų sintezė bei jų optinių savybių tyrimas. Taip pat siekta ištirti europį supančios aplinkos įtaką jo liuminescencinėms savybėms tiek milteliuose, tiek kristaluose. Milteliai buvo sintetinti zolių-gelių arba kietafazės reakcijos metodu. Kristalai auginti keliaujančio lydalo slankioje zonoje būdu. Medžiagų faziniai virsmai tirti Rentgeno spindulių difrakcijos metodu. Neutronų difrakcijos duomenys bei Rietveldo tikslinimas buvo panaudoti granatų struktūrinei analizei. Junginių optinės savybės įvertintos išmatavus atspindžio, sužadinimo ir emisijos spektrus.

Fluorescence microscopy offers the opportunity to image biological samples noninvasively in real time and has become an essential analytical tool in the biomedical laboratory. Nonetheless, the phenomenon of diffraction imposes stringent limitations on the resolving power of conventional microscopes, preventing the spatial resolution of fluorescent species co-localized within areas of nanoscaled dimensions. Time, however, can be exploited to distinguish fluorophores within the same subdiffraction area, if their fluorescence can be switched independently, and reconstruct sequentially their spatial distribution. In this context, photolytic reactions and photochromic transformations can be invoked to switch fluorescence under optical control. Fluorescent units, such as inorganic semiconductor nanoparticles and organic dyes, and photoactive components can be operated within a common supramolecular matrix or integrated within the same molecular construct to produce photoswitchable fluorescent assemblies. In the resulting systems, electronic communication between the components can be designed in order to photoactivate or photodeactivate fluorescence respectively. Both mechanisms can be exploited to overcome diffraction, and ultimately permit the reconstruction of images with resolution down to the nanometer level, in combination with appropriate illumination protocols.

The Indo-Australian Plate is actively deforming at its margins and within its interior. In south-central Australia, more than 3000 km from the closest active plate boundary, a geomorphically rugged and apparently youthful mountain range has developed, rising up to 1.1km above the adjacent flat-lying outback plains. These ‘Flinders’ and ‘Barrier’ Ranges are seismically active and bound by major reverse fault scarps with clear evidence for Plio-Quaternary displacements, implying that young and active intraplate tectonism has played a fundamental role in their development. Palaeoseismic investigations and optically stimulated luminescence (OSL) chronology indicate faulting occurred in response to a series of large magnitude (~M6.6 to M7.3) palaeo-earthquakes with recurrence intervals of ~1:20,000 to~1:80,000 yrs and long-term fault slip rates of ~50 m Myr-1. Geomorphic observations and 10Becosmogenic nuclide dating indicate surprisingly high and spatially variable rates of bedrock erosion from fault-affected catchments in the Flinders Ranges. Slowly eroding bedrock summit surfaces have been uplifted up to 12 m in the last 60,000-100,000 years relative to more rapidly eroding valley floors and bounding piedmonts, indicating Late Quaternary increases in elevation and relief in response to intraplate tectonism and erosion. However, both facies changes and sediment aggradation-dissection cycles in alluvial fan sequences are out-of-synch within dividual tectonic events, indicating that an aspect of climate (aridification, changing flood frequency-magnitude distributions) has governed the spatial-temporal distribution of range front sedimentation.

Thesis (Ph. D.)--Ohio University, 2001. / Title from PDF t.p.

Thesis (Ph.D.); Submitted to Iowa State Univ., Ames, IA (US); 12 Dec 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 2605" Chang-Hwan Kim. 12/12/2003. Report is also available in paper and microfiche from NTIS.

Thesis (Ph.D.)--Flinders University, School of Chemistry, Physics and Earth Sciences. / Typescript bound. Includes bibliographical references. Also available online.

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