Master of Science / Department of Computer Science / Mitchell L. Neilsen / Smart glasses, like smart phones, have separate operating systems, and can execute many different kinds of software and games. Smart glasses can be used to add a schedule, map navigation, interact with friends, take photos and videos, and make video calls with friends through voice control. They can support wireless network access through a mobile communication network. Bluetooth is a radio technology that supports short-range communication between of the devices. It can exchange information between devices including mobile phones, wireless headsets, laptops, etc. Bluetooth technology can effectively simplify the communication between mobile devices. This thesis focuses on smart glasses applications for high-throughput phenotyping which requires a data monitor, data synchronization, Bluetooth service, and voice control between devices. On the Android side, the application, which is extended, is called Field Book. The new software called Field Book AR, includes a data monitor module and a Bluetooth server module to achieve data exchange with smart glasses. On the smart glasses side, the application is called DataReceiver. It receives voice commands from users and controls the actions of Field Book AR. Also, when Field Book detects data changing, it accepts new data and shows changes to the users.

Nesta tese, apresentamos três estudos envolvendo técnicas de ressonância paramagnética eletrônica (RPE) de onda contínua e pulsada nas bandas X e Q em vidros e nanocompósitos dopados com íons de metais de transição. O objetivo geral deste texto é evidenciar a complementariedade destas técnicas no estudo destes materiais. Os dois primeiros estudos focam-se em vidros e vitro-cerâmicas dopados com íons de metais de transição. O objetivo destes estudos é analisar o efeito dos tratamentos térmicos no espectro de RPE das amostras. O primeiro estudo trata de vidros fosfo-germanato dopados com íons de vanádio e os resultados de RPE de onda contínua mostram que, para a amostra sem tratamento térmico e para a amostra tratada em temperaturas menores do que 470 °C, apenas um sítio de vanádio é observado enquanto que, para as amostras tratadas com temperaturas acima de 470 °C, um segundo sítio de vanádio, mais distorcido do que anterior, aparece. Experimentos de ESEEM e HYSCORE observaram a interação entre os íons de vanádio e núcleos 31P próximos e pudemos estimar a máxima densidade de spin transferida pelo mecanismo through-bond e máxima distância média entre o íon paramagnético e os núcleos 31P. O segundo estudo trata de um vidro fluorosilicato dopado com íons Cu2+ e os resultados de RPE de onda contínua não mostram alterações relevantes no sítio paramagnético devido ao tratamento térmico. Experimentos de ESEEM e HYSCORE mostraram picos devido a interação desse íon com núcleos 19F, 207Pb, 111Cd e 113Cd. O terceiro estudo foca-se numa argila natural laminar contendo íons Cu2+ e moléculas de polioxietileno (PEO). O objetivo deste estudo é analisar a complexação do íon Cu2+ com as moléculas de PEO e moléculas de água no espaço interlaminar da argila. Os resultados de RPE de onda contínua não evidenciaram alterações na coordenação do íon Cu2+ através dos dois métodos de preparação propostos. Os experimentos de ESEEM E HYSCORE mostraram que, para o método onde o complexo PEO-Cu é inserido no espaço interlaminar da argila, o íon Cu2+ interage apenas com prótons em, pelo menos, duas conformações diferentes. Nossa hipótese é que observamos prótons tanto da molécula de PEO quanto de moléculas de água. No método onde moléculas de PEO são inseridas no espaço interlaminar da argila previamente preenchido com íons Cu2+, tal hipótese não pode ser feita. Ainda, observamos outro centro paramagnético nas amostras oriundo de vacâncias de oxigênio nas lâminas da argila. / This thesis contains three studies where X- and Q-Band continous-wave electron paramagnetic resonance (CW-EPR) and pulsed EPR techniques were applied in glasses and nanocomposites doped with transition metal ions. Our general goal is to show the complementarity of these techniques for the study of this materials. The first two studies focus on glasses and glass-ceramics doped with transition metal ions and the main goal is to analyse the effect of sample heat treatments on the EPR spectra. The first study focuses on phospho-germanate glasses and the CW-EPR results show that, for non-treated samples or for heat-treated samples at temperatures below 470°C, only one vanadium site is observed, while for samples heat-treated at higher temperatures a second, more ditorted site is produced. ESEEM and HYSCORE experiments observe the interaction between vanadium ions and near 31P nuclei. The maximum spin density transfer by the through-bond mechanism and maximum average distance between the two species could be estimanted. The second study focuses on fluorosilicate glasses doped with Cu2+ and the CW-EPR results show no relevant changes in the paramagnetic site upon heat treatment. ESEEM and HYSCORE experiments display peaks due to the interaction between Cu2+ ions and 19F, 207Pb, 111Cd e 113Cd nuclei. The third study focus on a natural bentonite clay containing copper ions and polioxiethilene (PEO) molecules. The main goal of this study is to analyze the complexation of the Cu2+ ions with the PEO and water molecules in the interlaminar space of the clays. CW-EPR results does not show any changes in the Cu2+ coordination caused by the two preparation methods proposed. ESEEM and HYSCORE experiments, however, showed that, for the method where the PEO-Cu complex is inserted in the interlaminar space, the paramagnetic ion interacts only with protons in at least two different conformations. Our hypothesis is that both protons from the PEO chain and water molecules are being observed. In the method where PEO molecules are inserted in the material, which was previosly filled with Cu2+ ions, no such assignment could be made. In addition, another paramagnetic center is observed and associated with oxigen vacancies in the sheets of the clay.

Yin, Weixin = 非晶液態鈀-鎳-磷合金相位分離的證據 / 殷瑋欣. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Abstracts in English and Chinese. / Yin, Weixin = Fei jing ye tai ba-nie-lin he jin xiang wei fen li de zheng ju / Yin Weixin. / Acknowledgement --- p.i / Abstract --- p.ii / Contents --- p.iv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- A Brief Introduction to Metallic Glass --- p.1 / Chapter 1.2 --- Homogeneous Nucleation Frequency --- p.3 / Chapter 1.3 --- Heterogeneous Nucleation Frequency --- p.4 / Chapter 1.4 --- Spinodal Decomposition --- p.5 / Chapter 1.5 --- Conditions for Metallic Glasses Formation --- p.8 / Chapter 1.6 --- How to Get Large Undercooling --- p.9 / Chapter 1.7 --- Liquid Phase Separation --- p.10 / References --- p.12 / Figures --- p.13 / Chapter Chapter 2 --- Experimental Procedures and Techniques of Transmission Electron Microscopy --- p.18 / Chapter 2.1 --- Sample preparation --- p.18 / Chapter 2.1.1 --- Ni2P Preparation --- p.18 / Chapter 2.1.2 --- Alloying --- p.18 / Chapter 2.1.3 --- Fluxing --- p.18 / Chapter 2.2 --- Introduction to TEM Specimen Preparation --- p.19 / Chapter 2.2.1 --- "Grinding, Polishing and Punching" --- p.19 / Chapter 2.2.2 --- Final Thinning by Ion Miller --- p.20 / Chapter 2.2.3 --- Final Thinning by Twin Jet --- p.20 / Chapter 2.3 --- Introduction to Transmission Electron Microscopy Techniques --- p.21 / Chapter 2.3.1 --- Basic Instrumentations of TEM --- p.21 / Chapter 2.3.2 --- Elastic Scattering and Inelastic Scattering --- p.21 / Chapter 2.3.3 --- Image Contrast --- p.22 / Chapter 2.3.4 --- Dark Field Image and Bright Field Image --- p.24 / Chapter 2.3.5 --- EDX Mapping --- p.24 / Chapter 2.3.6 --- High Resolution Images --- p.25 / References --- p.26 / Figures --- p.27 / Chapter Chapter 3 --- Evidence of amorphous/liquid phase separation in Pd41.25Ni41.25P17.5 alloy --- p.32 / Chapter 3.1 --- Introduction --- p.32 / Chapter 3.2 --- Experimental --- p.34 / Chapter 3.3 --- Discussions --- p.42 / References --- p.44 / Figures --- p.45 / Chapter Chapter 4 --- Conclusions --- p.68

過去幾十年當中，金屬玻璃（包括塊狀金屬玻璃）中非晶相分離的發生已經成為了一個具有爭議性的課題。一些報告報導在具有負混合熱的Pd-Ni-P合金體系中發生了非晶相分離。然而，有一些報告聲稱相分離不能在Pd-Ni-P非晶合金中被觀察到。文獻分析表明，困難在於缺乏直接的實驗證據。 / 為了解決這個難題，示差掃描量熱儀、高分辨電子顯微鏡、掃描透射模式下的高角環射暗場相、以及能量色散X射線光譜儀等檢測儀器在我們實驗當中被使用。同時為了清楚展示非晶相分離反應，在過冷Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅熔體被冷卻為固態非晶樣品之前引入了中間熱退火處理。 / 實驗研究了三種經由不同路徑製備的A、B、C型號樣品。結果表明在非晶/液態Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅合金中可能存在獨特的短程有序結構，它會導致相分離的發生。同时研究發現，在大約625 K，調幅分解的持續時間的下限大概是200 s。調幅分解的時間常數R在大約625 K 下為0.002 s⁻¹。三种类型样品在不同的溫度下被退火從而獲得部分的結晶。A型號和B型號具有相似的行為。在低溫下，圓形的核心首先形成，接著發生共晶反應。在高溫下，出現了一種形狀為立方體的析出相。在C型號的樣品當中，核心和立方的析出物同時被發現。但是核心的成分分佈與A和B型號中出現的不同。同時，隨著退火時間的加長形核的數量也具有獨特的行為表現。作為對比，Pd₄₀Ni₄₀P₂₀塊狀金屬玻璃的結晶行為也被展開了研究。同樣的，以形成核心開始，但是它的成分分佈異於A和B型號的樣品。 / Amorphous phase separation in metallic glass (including bulk metallic glass) has been a controversial issue in the past several decades. There are reports saying that amorphous phase separation occurs in Pd-Ni-P, which has a negative heat of mixing among its constituent elements. However, there are also as many reports claiming that phase separation is absent in amorphous Pd-Ni-P alloys. The lack of direct experimental evidence makes the issue to be difficult to be resolved. / To solve this problem, differential scanning calorimetry (DSC), high resolution transmission electron microscopy (HRTEM), high angle annular dark field (HAADF) in scanning transmission electron microscopy, and energy dispersive X-ray spectroscopy (EDX) have been employed. Intermediate thermal annealing is introduced before an undercooled Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅ melt is cooled down to become a solid amorphous specimen. / A-type, B-type, and C-type specimens of composition, Pd₄₁.₂₅Ni₄₁.₂₅ P₁₇.₅, have been prepared via three different cooling paths. It was found that amorphous phase separation indeed occurs in C-type specimens. Results suggest that there may be unique short range orders in amorphous/liquid Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅, which are responsible for the phase separation. Experimental arrangements were made to study the occurrence of spinodal reaction in undercooled molten Pd₄₁.₇₅Ni₄₁.₇₅P₁₇.₅ alloys as a function of time. The lower bound of the duration of the spinodal decomposition at a temperature of {U+2248}625 K is about 200 s and the time constant R of the spinodal decomposition at a temperature of {U+2248}625 K is 0.002 s⁻¹. / A-type and B-type specimens have similar crystallization behavior. At low temperature, it starts with the formation of a spherical core and then eutectic crystallization takes over. At higher temperatures, an additional phase in the shape of a cube appears. In annealed C-type specimens, cores and cubic precipitates are also found. However, the composition profile of the cores is different and the number of nucleation events versus time has peculiar characteristics. The crystallization behavior of Pd₄₀Ni₄₀P₂₀ BMG was studied for comparison. It again starts out with the formation of a core, but with a composition profile different from those of A-type and B-type specimens. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lan, Si = 對於具有負混合熱的塊狀金屬玻璃非晶相分離的研究 / 蘭司. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Abstract also in Chinese. / Lan, Si = Dui yu ju you fu hun he re de kuai zhuang jin shu bo li fei jing xiang fen li de yan jiu / Lan Si. / Abstract of thesis --- p.i / Acknowledgements --- p.v / List of Tables --- p.x / List of Figures --- p.xi / Chapter Chapter 1 --- Introduction and literature review --- p.1 / Chapter 1.1 --- Introduction to metallic glasses --- p.1 / Chapter 1.1.1 --- Background of metallic glasses --- p.1 / Chapter 1.1.2 --- Glass transition --- p.2 / Chapter 1.1.3 --- The undercooling of liquids --- p.3 / Chapter 1.1.4 --- Crystal nucleation and growth in liquids --- p.3 / Chapter 1.1.4.1 --- Crystal Nucleation in liquids --- p.3 / Chapter 1.1.4.2 --- Crystal growth in liquids --- p.5 / Chapter 1.1.4.3 --- TTT diagram --- p.6 / Chapter 1.1.4.4 --- Crystallization in metallic glasses --- p.6 / Chapter 1.1.5 --- Glass formation methods and systems --- p.6 / Chapter 1.1.6 --- Glass forming ability and criteria --- p.8 / Chapter 1.1.7 --- Properties and applications --- p.9 / Chapter 1.2 --- The basic theory of phase separation in a binary system --- p.10 / Chapter 1.2.1 --- Thermodynamic background --- p.10 / Chapter 1.2.2 --- Solid state phase separation --- p.11 / Chapter 1.2.2.1 --- A miscibility gap of binary mixture --- p.11 / Chapter 1.2.2.2 --- Nucleation and growth mechanism --- p.12 / Chapter 1.2.2.3 --- Spinodal decomposition mechanism --- p.13 / Chapter 1.2.3 --- Liquid state miscibility gap in a binary system --- p.21 / Chapter 1.3 --- Literature review for phase separation in metallic glasses --- p.23 / Chapter 1.4 --- The aim of this thesis --- p.28 / Figures --- p.30 / References --- p.39 / Chapter Chapter 2 --- Experiments and characterization --- p.44 / Chapter 2.1 --- Introduction and the outline of the experiments --- p.44 / Chapter 2.2 --- Sample preparation --- p.45 / Chapter 2.2.1 --- Bulk metallic glasses preparation --- p.45 / Chapter 2.2.1.1 --- Preparation of clean fused silica tubes --- p.45 / Chapter 2.2.1.2 --- Weighing --- p.46 / Chapter 2.2.1.3 --- Alloying --- p.46 / Chapter 2.2.1.4 --- Fluxing --- p.47 / Chapter 2.2.2 --- Thermal annealing --- p.49 / Chapter 2.2.3 --- Specimens preparation for characterization --- p.50 / Chapter 2.2.3.1 --- Cutting, molding, grinding and polishing --- p.50 / Chapter 2.2.3.2 --- Etching --- p.51 / Chapter 2.2.3.3 --- Thinning for TEM foils --- p.51 / Chapter 2.3 --- Characterization --- p.55 / Chapter 2.3.1 --- Differential scanning calorimetry (DSC) --- p.55 / Chapter 2.3.2 --- Scanning electron microscopy (SEM) --- p.55 / Chapter 2.3.3 --- Transmission electron microscopy (CTEM and HRTEM) --- p.57 / Chapter 2.3.4 --- High angle annular dark field (HAADF) in Scanning transmission electron microscopy (STEM) --- p.58 / Chapter 2.3.5 --- Energy dispersive X-ray spectroscopy (EDX) --- p.59 / Figures --- p.62 / References --- p.69 / Chapter 3 --- p.70 / Chapter 3.1 --- Introduction --- p.70 / Chapter 3.2 --- Materials and Experimental --- p.73 / Chapter 3.3 --- Results --- p.75 / Chapter 3.3.1 --- Thermal behaviors of three types of specimens --- p.75 / Chapter 3.3.2 --- Microstructures of three types of specimens --- p.75 / Chapter 3.3.2.1 --- A-type specimens --- p.75 / Chapter 3.3.2.2 --- B-type specimens --- p.76 / Chapter 3.3.2.3 --- C-type specimens --- p.76 / Chapter 3.4 --- Discussion --- p.78 / Chapter 3.5 --- Conclusions --- p.79 / Chapter 3.6 --- Afterward --- p.79 / Figures --- p.80 / References --- p.89 / Chapter Chapter 4 --- The time constant of the spinodal decomposition in Pd₄₁.₇₅Ni₄₁.₇₅P₁₇.₅ bulk metallic glasses --- p.92 / Chapter 4.1 --- Introduction --- p.92 / Chapter 4.2 --- Materials and experimental --- p.92 / Chapter 4.3 --- Results --- p.94 / Chapter 4.3.1 --- Thermal behaviors --- p.94 / Chapter 4.3.2 --- Microstructures --- p.94 / Chapter 4.4 --- Discussion --- p.96 / Chapter 4.5 --- Conclusions --- p.98 / Figures --- p.100 / References --- p.123 / Chapter Chapter 5 --- Crystallization in homogeneous and phase-separated Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅ bulk metallic glasses --- p.125 / Chapter 5.1 --- Introduction --- p.125 / Chapter 5.2 --- Experiments --- p.126 / Chapter 5.3 --- Results --- p.128 / Chapter 5.3.1 --- Low temperature thermal annealing at 613 K with 0≤t{U+2090} ≤ 8 h --- p.128 / Chapter 5.3.1.1 --- A-type and B-type specimens --- p.128 / Chapter 5.3.1.2 --- C-type specimens --- p.130 / Chapter 5.3.1.3 --- Pd₄₀Ni₄₀P₂₀ BMG --- p.132 / Chapter 5.3.2 --- High temperature thermal annealing --- p.133 / Chapter 5.3.2.1 --- A-type and B-type specimens --- p.133 / Chapter 5.3.2.2 --- C-type specimens --- p.135 / Chapter 5.3.2.3 --- Pd₄₀Ni₄₀P₂₀ BMG --- p.137 / Chapter 5.4 --- Discussion --- p.137 / Chapter 5.4.1 --- Formation of spherical cores --- p.138 / Chapter 5.4.1.1 --- A-type and B-type Pd₄₁.₇₅Ni₄₁.₇₅P₁₇.₅ specimens --- p.138 / Chapter 5.4.1.2 --- C-type Pd₄₁.₇₅Ni₄₁.₇₅P₁₇.₅ specimens --- p.139 / Chapter 5.4.1.3 --- Pd₄₀Ni₄₀P₂₀ BMG --- p.140 / Chapter 5.4.2 --- Formation of cubic precipitates --- p.141 / Tables --- p.142 / Figures --- p.144 / References --- p.188 / Chapter Chapter 6 --- Conclusions --- p.190 / Bibliography --- p.192

by Yuen Cheong Wing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves [138]-[142]). / by Yuen Cheong Wing. / Acknowledgments --- p.ii / Abstract --- p.iii / Table of Contents --- p.v / Chapter Chapter 1: --- Introduction --- p.1-1 / Chapter 1.1 --- What is Metallic Glass? --- p.1-1 / Chapter 1.2 --- Use of Metallic Glass --- p.1-3 / Chapter 1.3 --- A Dilemma --- p.1-4 / Chapter 1.4 --- Glass Forming Ability --- p.1-5 / Chapter 1.5 --- Role of Liquid State Phase Separation in GFA --- p.1-6 / References --- p.1-9 / Figure --- p.1-10 / Chapter Chapter 2: --- Phase Separation Theory --- p.2-1 / Chapter 2.1 --- Free Energy Curve --- p.2-1 / Chapter 2.2 --- Nucleation and Growth --- p.2-2 / Chapter 2.2.1 --- Liquid state nucleation and growth --- p.2-2 / Chapter 2.2.2 --- Nucleation and growth during solidification --- p.2-4 / Chapter 2.3 --- Spinodal Decomposition --- p.2-5 / Chapter 2.3.1 --- Cahn-Hilliard linearized equation --- p.2-6 / Chapter 2.3.2 --- Temporal evolution --- p.2-9 / References --- p.2-12 / Figures --- p.2-15 / Chapter Chapter 3 ： --- Experimental Setup and Techniques --- p.3-1 / Chapter 3.1 --- Technique in Achieving High Undercooling --- p.3 -1 / Chapter 3.1.1 --- Effects and limitation of B203 --- p.3-1 / Chapter 3.1.2 --- Preparation of B203 --- p.3-3 / Chapter 3.1.3 --- Cleansing of apparatus --- p.3-4 / Chapter 3.2 --- Experimental --- p.3-5 / Chapter 3.2.1 --- Sample preparation --- p.3-6 / Chapter 3.2.2 --- Experimental setup --- p.3-7 / Chapter 3.2.3 --- Procedures --- p.3-8 / Chapter 3.3 --- Observing the Microstructure --- p.3-9 / Chapter 3.3.1 --- Cutting --- p.3-10 / Chapter 3.3.2 --- Molding --- p.3-10 / Chapter 3.3.3 --- Polishing --- p.3-11 / Chapter 3.3.4 --- Etching --- p.3-12 / Chapter 3.3.5 --- Observation --- p.3-12 / References --- p.3-14 / Table --- p.3-15 / Figures --- p.3-16 / Chapter Chapter 4: --- Metastable liquid phase separationin undercooled molten PD40. 5]\l40.5P19 --- p.4-1 / Abstract --- p.4-1 / References --- p.4-9 / Figures --- p.4-10 / Chapter Chapter 5 ： --- Transformation in undercooled molten PD40.5NI40.5P19 --- p.5-1 / Chapter 5.1 --- Abstract --- p.5-1 / Chapter 5.1 --- Introduction --- p.5-2 / Chapter 5.3 --- Experimental --- p.5-4 / Chapter 5.4 --- Results --- p.5-6 / Chapter 5.5 --- Discussions --- p.5-13 / References --- p.5-20 / Figures --- p.5-22 / Chapter Chapter 6 ： --- Solidification of liquid spinodal in undercooled PD40.5NI40.5P19 --- p.6-1 / Chapter 6.1 --- Abstract --- p.6-1 / Chapter 6.2 --- Introduction --- p.6-2 / Chapter 6.3 --- Experimental --- p.6-3 / Chapter 6.4 --- Results --- p.6-5 / Chapter 6.5 --- Discussions --- p.6-10 / References --- p.6-17 / Figures --- p.6-18 / Chapter Chapter 7: --- Conclusion --- p.7-1 / References --- p.7-4 / Bibliography --- p.B-1

Neste trabalho foi investigada uma mudança na linha base observada em curvas de calorimetria exploratória diferencial em um trabalho onde microesferas de vidros aluminossilicatos contendo Ho foram estudados para a aplicação em radioterapia interna seletiva para o tratamento de carcinoma hepatocelular. Os vidros com composição nominal 53,7 SiO2 .10,5 Al2O3 . 35,8 MgO em %mol foram produzidos pelo método de fusão tradicional. As fritas obtidas foram moídas e peneiradas na faixa de 45 a 63 μm. O material foi utilizado para produzir microesferas pelo método de esferolização por queda gravitacional. O pó de vidro e as microesferas foram caracterizados por espectrometria de fluorescência de raios X, difração de laser, difração de raios X, calorimetria exploratória diferencial, análise térmica diferencial, termogravimetria, espectrometria de massa e microscopia eletrônica de varredura. Após as análises térmicas foram formadas pastilhas nos cadinhos que foram analisadas por microscopia eletrônica de varredura, difração de raios X e picnometria a gás He. A mudança na linha base foi associada ao processo de sinterização por fluxo viscoso e ocorre devido a diminuição do fluxo de calor detectado devido à retração da amostra. Outros processos como cristalização concomitante com a sinterização também foram estudados. / In this work a difference in the baseline in differential scanning calorimetry analyses, observed in a work where aluminosilicate glasses microspheres containing Ho were studied for application in selective internal radiotherapy as hepatocellular carcinoma treatment, was studied. The glasses with nominal composition 53,7 SiO2 .10,5 Al2O3 . 35,8 MgO in %mol were produced from traditional melting. The frits obtained were milled and sieved in the range of 45 a 63 μm. The material was used to produce glass microspheres by the gravitational fall method. The glass powder and the microspheres were characterized by X ray fluorescence spectrometry, laser diffraction, X ray diffraction, differential scanning calorimetry, differential thermal analysis, thermogravimetry, mass spectrometry, and scanning electron microscopy. After the thermal analyses, pellets were formed in the crucibles and were analyzed by scanning electron microscopy, X ray diffraction, and He picnometry. The difference in the baseline was associated to the viscous flow sintering process and happens because of the decrease in the detected heat flow due to the sample shrinkage. Other events as concurrent crystallization with the sintering process were also studied.

Doctor of Philosophy (PhD) / The glass-transition traverses continuously from liquid to solid behaviour, yet the role of structure in this large and gradual dynamic transition is poorly understood. This thesis presents a theoretical study of the relationship between structure and dynamics in two-dimensional glass-forming alloys, and provides new tools and real-space insight into the relationship at a microscopic level. The work is divided into two parts. Part I is concerned with the role of structure in the appearance of spatially heterogeneous dynamics in a supercooled glass-forming liquid. The isoconfigurational ensemble method is introduced as a general tool for analysing the effect that a configuration has on the subsequent particle motion, and the dynamic propensity is presented as the aspect of structural relaxation that can be directly related to microscopic variations in the structure. As the temperature is reduced, the spatial distribution of dynamic propensity becomes increasingly heterogeneous. This provides the first direct evidence that the development of spatially heterogeneous dynamics in a fragile glass-former is related to spatial variations in the structure. The individual particle motion also changes from Gaussian to non- Gaussian as the temperature is reduced, i.e. the configuration expresses its character more and more intermittently. The ability of several common measures of structure and a measure of structural ‘looseness’ to predict the spatial distribution of dynamic propensity are then tested. While the local coordination environment, local potential energy, and local free volume show some correlation with propensity, they are unable to predict its spatial variation. Simple coarse-graining does not help either. These results cast doubt on the microscopic basis of theories of the glass transition that are based purely on concepts of free volume or local potential energy. In sharp contrast, a dynamic measure of structural ‘looseness’ - an isoconfigurational single-particle Debye-Waller (DW) factor - is able to predict the spatial distribution of propensity in the supercooled liquid. This provides the first microscopic evidence for previous correlations found between short- and long-time dynamics in supercooled liquids. The spatial distribution of the DW factor changes rapidly in the supercooled liquid and suggests a picture of structural relaxation that is inconsistent with simple defect diffusion. Overall, the work presented in Part I provides a real-space description of the transition from structure-independent to structure-dependent dynamics, that is complementary to the configuration-space description provided by the energy landscape picture of the glass transition. In Part II, an investigation is presented into the effect of varying the interparticle potential on the phase behaviour of the binary soft-disc model. This represents a different approach to studying the role of structure in glass-formation, and suggests many interesting directions for future work. The structural and dynamic properties of six different systems are characterised, and some comparisons are made between them. A wide range of alloy-like structures are formed, including substitutionally ordered crystals, amorphous solids, and multiphase materials. Approximate phase diagrams show that glass-formation generally occurs between competing higher symmetry structures. This work identifies two new glass-forming systems with effective chemical ordering and substantially different short- and medium-range structure compared to the glassformer studied in Part I. These represent ideal candidates for extending the study presented in Part I. There also appears to be a close connection between quasicrystal and glass-formation in 2D via random-tiling like structures. This may help explain the experimental observation that quasicrystals sometimes vitrify on heating. The alignment of asymmetric unit cells is found to be the rate-limiting step in the crystal nucleation and growth of a substitutionally ordered crystal, and another system shows amorphous-crystal coexistence and appears highly stable to complete phase separation. The generality of these results and their implications for theoretical descriptions of the glass transition are also discussed.

A high temperature high vacuum rheometer has been designed, fabricated, and tested for the study of the steady shear viscosity for multicomponent bulk metallic glass forming alloys. This rheometer has an operating range up to 1525 K, rotational frequencies of 9.4*10⁻³-3.7*10¹ radians/s, and a calibrated viscosity range of 9.6*10⁻³ and 1.2*10² Pa*s while maintaining absolute pressures pressure < 1*10⁻⁶ mbar. Zr[subscript 41.2]Ti[subscript 13.8]Cu[subscript 10.0]Ni[subscript 12.5]Be[subscript 22.5] (Vitreloy 1) is reported. The unexpected findings of non-Newtonian behavior above the liquidus temperature were observed. Observations of shear thinning, thixotropic, and viscoelastic behaviors have been made. Our results show that Vitreloy 1 can be modeled as a power law fluid, with a power law exponent of approximately -0.5 for high shear rates. We attribute the non-Newtonian behavior to structural ordering within the melt. The technological and scientific implications for non-Newtonian behavior are discussed. / Graduation date: 2005

This thesis concerns and combines the results of experimental studies of magnetocaloric, multiferroic and spin-glass materials, using SQUID magnetometry as the main characteriza-tion technique.  The magnetocaloric effect offers an interesting new technology for cooling and heating applications. The studies of magnetocaloric materials in this thesis are focused on experimen-tal characterization of fundamental magnetic properties of Fe2P-based materials. These are promising magnetocaloric materials with potential industrial use. It is found that the magneto-caloric properties of Fe2P can be optimally tuned by substitution of manganese for iron and silicon for phosphorus. Furthermore, a simple device to measure the magnetocaloric effect in terms of the adiabatic temperature change was constructed.  Materials that simultaneously exhibit different types of ferroic order, for example magnetic and electrical order, are rare in nature. Among these multiferroic materials, those in which the ferroelectricity is magnetically-induced, or vice versa the magnetism is electrically-induced, are intensively studied due to a need for new functionalities in future data storage and logic devices. This thesis presents results on two materials: Co3TeO6 and Ba3NbFe3Si2O14, which belong to the group of magnetically-induced ferroelectrics and exhibit strong coupling be-tween the magnetic and the electrical order parameter. Their ordering properties were studied using magnetic and electrical measurement techniques. The coupling between the magnetic and electronic degrees of freedom was investigated using high-field and low-temperature Raman spectroscopy.  Spin-glass materials exhibit complex magnetism and disorder. The influence of the spin dimensionality on the low and high magnetic field properties of spin glasses was investigated by studying model Heisenberg, XY and Ising spin-glass systems. Significant differences were found between the non-equilibrium dynamics and the hysteresis behavior of Heisenberg systems compared to those of XY and Ising spin glasses.

Transparent glass-ceramics have been of industrial interest because of their multifarious applications. These are becoming increasingly important because of the flexibility that is associated with this route of fabricating intricate sizes and shapes as per the requirement. A number of glass-ceramics, based on well known ferroelectric crystalline phases (LiNbO3, LaBGeO5, SrBi2Nb2O9, Bi2WO6 etc.) were fabricated and their polar and electro-optic properties were reported. Keeping the potential applications of transparent glass-nano/microcrystal composites in view, attempts were made to fabricate SrBi2B2O7 and CaBi2B2O7 glasses and glass-nano/microcrystal composites. An attempt has been made to employ strontium bismuth borate SrBi2B2O7 (SBBO) as a reactive host glass matrix for growing the nanocrystals of ferroelectric oxides belonging to the Aurivillius family. The in situ nucleation and growth of SrBi2Nb2O9 (SBN) nanocrystals in a reactive SrBi2B2O7-Nb2O5 system and its influence on various physical (dielectric, pyroelectric and optical) properties were investigated. The strategy has been to visualize the formation of nanocrystalline SrBi2Nb2O9 as a result of the simple chemical reaction between glassy SrBi2B2O7 and Nb2O5. Indeed at lower concentrations of Nb2O5 transparent glasses were obtained which upon heat-treatment at appropriate temperatures yielded nanocrystalline SrBi2Nb2O9 phase in a transparent glass matrix. Textured SrBi2Nb2O9 ceramics were obtained by quenching the melts of SrBi2B2O7-Nb2O5 in equimolar ratio and their physical properties were studied. A strong anisotropy in physical properties (which are akin to single crystals) were demonstrated in the textured ceramics.