Using the liquid phase epitaxy technique (LPE) Ga0.86In0.14As0.13Sb0.87 layers lattice-matched to (100) Te-GaSb have been deposited, which were intentionally doped with Te and Zn in a wide range. The Raman spectra show that the layers become more defective as the dopant molar fraction is increased. Two main vibrational bands are observed in the Raman spectra centred at 230 and 245 cm-1 that depend strongly on the Te (Zn) molar concentration, which are assigned to the vibrational modes GaAs-like and to (GaSb+InAs)-like mixture. The low-temperature photoluminescence of n (p)-type GaInAsSb was obtained as a function of Te (Zn) concentration added to the melt solution. The photoluminescence was interpreted taking into account nonparabolicity of the conduction (valence) band. It is shown that the band-to-band radiative transition energy can be used to estimate the free carrier concentration in GaInAsSb, for a wide range of doping concentration.

Ladle refining plays a key role in achieving the quality of the steel since in this reactor temperature and chemical composition is adjusted, elimination of non-metallic inclusions is performed, and also deoxidation and desulphurization are operations taking place in the refining process. Specifically, the metal-slag mass exchanges have not received much attention through scientific studies. In this work, a rigorous study on the mass exchange between metal and slag is presented through a scaled water physical model. In the model, thymol (playing the role of a solute such as sulfur) is added to the water (playing the role of steel) and silicon oil (playing the role of slag) picks up the thymol, while the ladle is agitated with the central injection of gas. The evolution of thymol concentration in time was measured. Also, a mathematical model was developed and cast into the commercial CFD code Fluent Ansys to represent the fluid flow phenomena and the mass transfer through the solution of the continuity equation, the turbulent momentum conservation equations and the species mass conservation equation. There is a good agreement between the measured and the computed results regarding the thymol concentration evolution in water and consequently the mathematical model was validated regarding the mass species metal-slag exchanges and it may be used to study metal-slag exchanges in the steel ladle such as deoxidation or desulphurization.

Carbon films were energetically deposited onto copper foil using the physical vapor deposition technique filtered cathodic vacuum arc. Raman spectroscopy and x-ray absorption spectroscopy showed that high quality graphene films of uniform thickness can be deposited onto copper foil at temperatures of 850 °C. The films can be prepared at high deposition rates (∼1 nm/min) and were comparable to graphene films grown at 1050 °C using chemical vapor deposition. This lower growth temperature was made possible by the energetic carbon flux which assisted the arrangement of carbon atoms into graphene layers on the Cu growth surface. Floating substrate potential was found to produce the highest quality graphene and the addition of hydrogen gas during film growth resulted in more defective films.

A systematic study was performed concerning the production, characterization, and application of BDD and BDND films grown on Ti substrate to degrade brilliant green dye using an electrochemical flow reactor. Films were grown in a hot filament chemical vapour deposition (HFCVD) reactor using H2/CH4 (BDD) and H2/CH4/Ar (BDND) gas mixtures. Boron doping was performed by dissolution of B2O3 in methanol in the appropriate B/C ratio to obtain good conductive electrodes. The electrolysis was carried out using BDD/Ti and BDND/Ti as anode material analyzing the influence of different current densities and flow rates. During the electrolysis, aliquots of the treated solution were analyzed by UV-Vis and Total Organic Carbon (TOC) measurements. The electrode efficiencies were compared considering the color removal as well as the TOC mineralization in the end of each electrolysis. The absorption bands intensity from UV/Vis spectra clearly decreased up to their completely vanishing at current density of 100 mA/cm2 for both electrodes. These results were corroborated by TOC measurements where 50% of the organic material was removed.

A novel method to fabricate uniform epitaxial graphene on C-face SiC substrates was investigated. Graphene was grown on the C-face 6H-SiC substrates with a sputtered SiC film by annealing temperatures ranging from 1400 to 1900 °C under an Ar ambient. The fractional area of the graphene having the layer number of two was about 95% in a 75×75 μm square by a Raman mapping and a low energy electron microscopy. Graphene on the C-face SiC fabricated by this method is quite uniform compared to that made by a conventional method without the sputtered SiC films and is thus suitable for high frequency analog devices.

We proposed an MgO barrier which is fabricated by combination of rf-sputter deposition of MgO film and subsequent in-situ post oxidation (PO). We found that the perpendicular magnetic anisotropy (PMA) of the CoFeB layer formed on this MgO barrier with PO was improved. We also found that a short error rate reduced drastically and a magnetoresistance (MR) ratio increased about 20% for the magnetic tunnel junction (MTJ) with this MgO barrier with PO. In addition, we showed that this MgO barrier with PO has long endurance life compared with conventional sputtered MgO barriers, and has a potential to operate over 1016 write cycles.

Furthermore, we have observed that the PO could suppress the Fe diffusion into the MgO barrier and form Fe-O bonding at MgO/CoFeB interface using electron energy-loss spectroscopy (EELS). The obtained results might be involved to the improvement of PMA and MTJ characteristics.

A simulation method is presented which encompasses all relevant mechanisms, which are necessary for the description of the early stages of particle formation in arc discharges. Next to discrete coagulation and nucleation events, a continuous surface growth process is included into the simulation, making thus the description of the evaporation of thermodynamic unstable particles possible. The driving force for the nucleation and growth/evaporation is coupled to the monomer concentration in the gaseous phase and thus subject to change in the further course of the simulation. It is shown, that the simulation results gained by the incorporation of all three of these processes cannot be reproduced, if one of those processes is not simulated.

Thin films of NbO2 are synthesized by oxide molecular-beam epitaxy on (001) MgF2 substrates, which are isostructural (rutile structure) with NbO2. Two growth parameters are systematically varied in order to identify appropriate growth conditions: growth temperature and the partial pressure of O2 during film growth. θ-2θ X-ray diffraction measurements identify two dominant phases in this system at background oxygen pressures in the (0.2–6)×10–7 Torr range: rutile NbO2 is favored at higher growth temperature, while Nb2O5 forms at lower growth temperature. Electrical resistivity measurements were made between 350 K and 675 K on three epitaxial NbO2 films in a nitrogen ambient. These measurements show that NbO2 films grown in higher partial pressures of molecular oxygen have larger temperature-dependent changes in electrical resistivity and higher resistivity at room temperature.

A Ga0.8Fe1.2O3 epitaxial thin film was fabricated on a SrTiO3(111) substrate using pulsed laser deposition. The film is c-axis-oriented and has multiple in-plane domains. In-plane magnetization measurements show that it exhibits ferrimagnetic behavior with a Curie temperature (TC) of 290 K. The insulating film exhibits hopping conduction with a resistivity (ρ) of 4 × 105 Ωcm at 300 K. The ρ value is four orders lower than that of a BiFeO3 film, probably owing to the formation of multiple in-plane domains in the Ga0.8Fe1.2O3 film. Positive magnetoresistance with a maximum value of 3.5% near TC was observed, suggesting that antiferromagnetic interaction between Fe3+ ions decreases carrier transfer between the ions.

The mechanical properties of as-sintered and heat-exposed polycrystalline Mg2Si were investigated. The strength of the as-fabricated specimen depends on the surface flaws. After heat exposure in Ar atmosphere, oxidized products formed, mainly consisting of MgO. The strength increased after the heat exposure, and the surface oxidation product filled the surface cracks. After the surface oxidation products were removed, the strength and TE properties were the same as those of the as-fabricated specimens.

In this work, a new method is presented to synthesize graphene-C60 hybrid materials using an electrophoretic deposition technique to study the graphene-C60 interactions. Electronic measurements of the structure were conducted before and after the attachment of C60 clusters at different applied voltages on graphene devices. The assembled clusters of C60 on mechanically exfoliated graphene were investigated using Raman Spectroscopy and Scanning Electron Microscopy (SEM), which reveal a uniform morphology of C60 on graphene. The results indicate that graphene-C60 hybrids are excellent electron accepting/charge transporting materials which can provide an effective route to facilitate the application of these hybrids in electronic or opto-electronic device platforms.

In disposal of high-level radioactive waste, carbon steel overpack will be corroded after closure of the repository, creating a reducing, low-pH environment around the repository. A plutonium diffusion experiment was performed over 15 years with Kunigel V1, which is a typical Japanese bentonite that contains about 50% montmorillonite, in contact with an iron coupon. A tracer solution (10 µL) containing 1 kBq of 238Pu was applied at the interface between the iron coupon and compacted bentonite that was saturated with deionized water. After the diffusion period, the plutonium distribution in the bentonite specimen was measured with an alpha scintillation counter, and the iron and sodium distributions were obtained by inductively coupled plasma-mass spectrometry. Plutonium penetrated into the bentonite to a depth of 2 mm, and more than 90% of plutonium remained in corrosion product at the interface. The bentonite around the interface was dark green like green rust or magnetite according to visual observation. Iron was detected throughout the bentonite and there was a particularly high iron concentration from the interface to a depth of 2 mm, whereas the sodium concentration decreased slightly from the interface to 2 mm. We proposed that ferrous ions diffused into bentonite as the iron coupon corroded and precipitated such as magnetite. The magnetite precipitation would decrease the bentonite pH, resulting in the dissolution and migration of plutonium. Small cracks were also observed 2 to 6 mm from the interface and could have been formed by the migration of hydrogen generated by corrosion.

Two-sided oxidation experiments were recently conducted at 1000-1200°C in flowing steam with samples of sponge-based Zr-1Nb alloy E110. Although the old electrolytic E110 tubing exhibited a high degree of susceptibility to nodular corrosion and experienced breakaway oxidation rates in relatively short time, the new sponge-based E110 has demonstrated steam oxidation behavior comparable to Zircaloy-4. The sponge-based E110 followed the parabolic law, and the derived oxidation rate constant is in good agreement with the Cathcart-Pawel (CP) correlation at 1100-1200°C. For 1000°C oxidation, the weight-gain of sponge-based E110 is much lower than Zircaloy-4. No breakaway oxidation was observed at 1000°C up to 8000 s. Ring compression tests were conducted to evaluate the residual ductility of oxidized samples at room temperature and at 135°C. All sponge-based E110 specimens were still ductile at 135°C after being oxidized up to 20% equivalent cladding reacted at 1000-1200°C. Metallographic examinations were performed on oxidized E110 specimens to correlate material performance with microstructure.