Delafossite CuFeO2 is an intrinsic p-type semiconductor with a band gap around 1.5 eV. Further, it is composed of relatively abundant, nontoxic elements, and therefor have potential to be an attractive material for solar energy harvesting.This work examines three routes to synthesise this material. The first includes a sol-gel deposition and then relies on solid state reaction above 650 degrees Celsius in inert gas atmosphere. In this work, no delafossite is obtained with this method.The second method is a hydrothermal route to make particles under hydrostatic pressure in an autoclave. Delafossite is obtained mixed with other phases.The third route includes aqueous precipitation similar to the second route, but a temperature of 70 degrees Celsius and ambient pressure is sufficient to produce a pure delafossite particle phase. It provides a robust and simple way to make delafossite CuFeO2 particles.The resulting particles are deposited and compressed on glass into thin films.The films have a band gap slightly below 1.5 eV and show some photoactivity in electrochemical measurements.

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The global warming has increased with unprecedented levels during the last couple of decades and the trend is uprising. The construction industry is responsible for nearly 10% of all carbon emissions, mainly due to the increasing global population and the large demand for housing and civil infrastructure. Concrete, which is the most used construction material worldwide, is found in every type of building as it provides long term structural stability, support and its main constituent cement, is very cheap. Consequently, due to the raising concerns of high average temperatures, the research community started investigating new, innovative methods for substituting cement with 'greener' materials whilst at the same time improving the intrinsic properties of concrete. However, the manufacturing complications and logistics of these materials make them unfavourable for industrial applications. A novel and truly revolutionary method of enhancing the performance of concrete, thus allowing for decreased consumption of raw materials, lies in nanoengineering the cement crystals responsible for the development of all mechanical properties of concrete. Graphene, a two-dimensional sheet of carbon atoms arranged in a hexagonal lattice, is the most promising nanomaterial for composites' reinforcement to this date, due to it's exceptional strength, ability to retain original shape after strain, water impermeability properties and non-hazardous large scale manufacturing techniques. I chose to investigate the addition of liquid-phase exfoliated graphene suspensions for concrete reinforcement, aiming to improve the fundamental mechanical properties of the construction material and therefore allowing the industry to design buildings using less volume of base materials. First, the method of liquid exfoliation of graphene was developed and the resulting water suspensions were fully characterised by Raman spectroscopy. Then, concrete samples were prepared according to British standards for construction and tested for various properties such as compressive and flexural strength, cyclic loading, water impermeability and heat transport. A separate, in-depth, study was carried out to understand the formation and propagation of micro-structural cracks between the concrete's internal matrix planes, and graphene's impact on total fracture capacity and resistance of concrete. Lastly, multiple experiments were performed to investigate the microcrystallinity of cement hydration products using X-Ray diffraction. In general, all experimental results show a consistent improvement in concrete's performance when enhanced with graphene on the nanoscale level. The nanomaterial improves the mechanical interlocking of cement crystal, thus strengthening the internal bonds of the composite matrix. This cheap and highly scalable method for producing and mixing graphene with concrete turns it into the first truly applicable method for industrial applications, with a real potential to have positive impact on the global warming by decreasing the production of concrete.

Zinc oxide is a very versatile material that can be used in many microsystems and MEMS applications. ZnO thin film has been utilized in a wide variety of MEMS devices because of its unique piezoelectric, optical, and electrical properties. In particular, piezoelectric property of ZnO can be used in numerous applications from resonators and filters to mass sensors and micro-actuators (e.g., micro-valve and micro-pump). Because of its versatility, this research was focused on analyzing some key properties of ZnO thin film achieved by two different deposition techniques, Pulsed Laser Deposition (PLD) and Sputtering. Multiple experiments were conducted in order to identify the best conditions for the growth of ZnO thin film. Under the optimum conditions, the ZnO thin films will provide the best piezoelectric performance in devices such as microcantilevers. In order to find the best deposition conditions in both PLD and Sputtering multiple depositions have been done and then analyzed using the XRD, AFM, FTIR, nanoindenter, and ellipsometer. For the PLD the best conditions were found to be at 200°C with a partial pressure of O2 of 100 millitorr. For the sputtering system the best film formed when the substrate temperature was kept at 400°C along with RF power of 250 Watts, and a flow rate of 25% O2 and 75% Ar. Both experiments were similar in the fact that both a certain amount of O2 in the chamber and an elevated temperature are needed to facilitate the formation of ZnO crystal structure.

Semiconductor nanocrystals are expected to play an important role in the development of new generation of microelectronic and photonic devices such as light emitting diodes and memory elements. Optimization of these devices requires detailed investigations. Various spectroscopic techniques have been developed for material and devices characterization. This study covers the applications of the following techniques for the analysis of nanocrystalline materials: Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, X-Ray Diffraction (XRD) and X-Ray Photoelectron (XPS). Transmission Electron Microscopy (TEM) and Secondary Ion Mass Spectrometry (SIMS) are also used as complementary methods. Crystallinity ratio, size, physical and chemical environment of the nanostructures were probed with these methods. Si and Ge nanocrystals were formed into the oxides Al2O3 and SiO2 by ion implantation, magnetron sputtering and laser ablation methods. FTIR and XPS are two methods used to extract information on the surface of the nanocrystals. Raman and XRD are non destructive and easy-to-operate methods used widely to estimate the crystallinity to amorphous ratio and the sizes of the nanocrystals. In this study, the structural variations of SiO2 matrix during the formation of Si nanocrystals were characterized by FTIR. The shift in position and changes in intensity of the Si-O-Si asymmetric stretching band of SiOx was monitored. An indirect metrology method based on FTIR was developed to show the nanocrystal formation. Ge nanocrystals formed in SiO2 matrix were investigated using FTIR, Raman and XRD methods. FTIR spectroscopy showed that Ge atoms segregate completely from the matrix at relatively low temperatures 900 oC. The stress between the Ge nanocrystals and the matrix can vary in samples produced by magnetron sputtering if the production conditions are slightly different. Si and Ge nanocrystals were formed into Al2O3 matrix by ion implantation of Si and Ge ions into sapphire matrix. Raman, XRD, XPS and TEM methods were employed to characterize the formed nanocrystals. XRD is used to estimate the nanocrystal sizes which are in agreement with TEM observations. The stress on nanocrystals was observed by Raman and XRD methods, and a quantitative calculation was employed to the Si nanocrystals using the Raman results. XPS and SIMS depth profiles of the sample implanted with Si, and annealed at 1000 oC were measured. Precipitation of Si atoms with the heat treatment to form the nanocrystals was observed using XPS. The volume fraction of the SiOx shell to the Si core in Si nanocrystals was found to be 7.9 % at projection range of implantation.

Synthetic diamond thin films have potential for fabricating high-temperature semiconducting and optical devices because of its extraordinary properties. In this work, a microwave plasma chemical vapor deposition system has been setup. A two-steps deposition process will be applied for the growth of boron-doped diamond on silicon and on porous silicon. The effects of temperature, microwave power and of doping concentration of B2O3 have been studied by varying the growth parameters. The doping source of B2O3 solved in C2H5OH is applied with carrying gas of Ar. To vary the concentration of boron with the flow of Ar is controlled mixing into a reaction gas of CH4 and H2 mixture. Polycrystalline diamond thin films are examined by Raman, XRD and FTIR. In the SEM photograph a nano-wires structure has been found for higher doping of B2O3. A higher temperature the growth rate of the boron-doped diamond films will increase and the shape of crystallites will tend to polycrystalline. The diamond growth is in multi steps and the mechanism of deposition will change when the boron-doped diamond film grows up to a critical thickness. In this work a smooth diamond film was successfully grown on porous silicon without the step of nucleation.

Recently, wet sand blasting on coated cutting tool inserts has drawn interest to the tooling industry due to its positive effects on cutting performance and tool life. This performance boost has partly been attributed to the buildup of compressive residual stresses in the coating during the blasting process. However, the mechanism of forming residual stresses in ceramic coatings during sand blasting is not fully understood. This work utilize x-ray diffraction as the main tool to study the formation and relaxation of residual stresses after wet sand blasting and annealing on 001, 012 and 110 textured α-Al2O3 coatings. To minimize the influence of stress gradients in the samples, all stress measurements were set up with a fixed analysis depth of 2 µm. Sand blasting was made with an alumina based slurry at 2, 3.2 and 4 bar pressure and the anneal was done at temperatures from 400 to 1000 °C for 2 hours or more. The coating hardness was evaluated by nanoindentation. Finally, the activation energy for the relaxation of residual stresses was estimated using the Zener-Wert-Avrami function. The results reveal the highest compressive residual stress with up to -5.3 GPa for the 012 texture while the stresses for the 001 and 110 textures peaked at -3.1 and -2.0 GPa, respectively. Further, a hardness gradient was present after blasting of the 001 and 012 textured samples indicating a higher stress at the surface of the coating. The 110 textured sample is the most brittle resulting in flaking of the coating during sand blasting. The different deformation mechanisms are related to difference in active slip planes between coatings with different textures. Both the stress and hardness decreased after heat treatment and the activation energy for stress relaxation was found to be as 1.1 ± 0.3 eV, 1.9 ± 0.2 eV and 1.2 ± 0.1 eV for the 001, 012 and 110 textures, respectively.

In recent years, tissue engineering has shown great potential in treatment of injured tissues which aims to create artificial structures for cells to regenerate new tissues for replacing the damaged and diseased ones. The selection of scaffold materials is one of the critical factors affecting tissue healing process. Among a wide range of scaffold materials, chitosan (CS) has been demonstrated as an ideal material due to its biocompatibility, nontoxicity, biodegradability, antibacterial activity and favorable strength and stiffness. However, its insufficient mechanical properties limits its feasibility and scope for clinical application, especially for bone scaffolds. The main purpose of the study is to explore the potential of incorporation of nanofillers into CS to enhance the mechanical properties for tissue engineering. In this work, nanodiamond (ND) is applied and studied due to its high surface to volume ratio, rich surface chemistry, high mechanical strength, and excellent biocompatibility. ND/CS nanocomposites with different diamond concentration from 1wt. % to 5wt. % were synthetized through a solution casting method. The microstructure and mechanical properties of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), and nanoindentation. Compared with pristine CS, the addition of ND resulted in a dramatic improvement of mechanical properties, including a 239%, 276%, 321%, 333%, and 343% increase in Young’s modulus and 68%, 96%, 114%, 118%, and 127% increase in hardness when ND amount is 1wt. %, 2wt. %, 3wt. %, 4wt. %, and 5wt. %, respectively. The strong interaction between ND surface groups and chitosan matrix is of great importance in changing polymer structure and improving mechanical properties. The cell viability and cytotoxicity of the nanocomposite were also studied using MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. The results show that the addition of ND has no negative effect on cell viability and the nanocomposites have no cytotoxicity.

The proportion of authigenic to detrital clay minerals in terrestrial sediments is variable. It has previously been hypothesized that pure Mg-silicates in regions such as Amboseli Basin in Kenya occur due to the absence of Al-rich detritus. We tested this by replicating two Mg-silicate synthesis experiments while adding Al-rich smectite. The first study produced an X-ray amorphous Mg-silicate gel, with little response to addition of Al-rich smectite. The second experiment shifted the 060 peak associated with clay octahedral sheets, suggesting we synthesized trioctahedral domains in a smectite structure. Peak height increased linearly with more heating, indicating crystallinity changes. These results confirm that Al-rich detritus can influence the mineralogy of authigenic clays in saline, alkaline settings. By examining how clay neoformation is affected by silica saturation, we can better understand how the clays found in Neogene lacustrine environments are formed and the climate and of that time.

The characteristics of crystallized fats depend on their solid fraction (SF) and fractal structures, which are affected by shear during crystallization. Binary mixtures of trilaurin (LLL) and trimyristin (MMM) diluted in triolein were used as samples. Pure diluted LLL and MMM were also studied. Samples were examined at different crystallization temperatures either statically or at shear rates of 800, 80, and 8 1/s. The sample cell combined a rheometer with a nuclear magnetic resonance (NMR) device to measure SF value and apparent viscosity. The measurements were compared to equations that describe the dependency of viscosity on solid volume fraction, to understand the effect of crystallites orientation at higher shear rates. Phase transitions during crystallization were observed by time-resolved synchrotron X-ray diffraction under similar conditions. Shear induced a strong reduction in phase onset and transition time and variations in phase distributions and the crystal size.