We have studied the effect that applying self-interaction correction (SIC) to oxygen p orbitals has on the magnetic moment formation of three polar ZnO surfaces; all of them being oxygen terminated. For these investigations we have used a multi-code approach. This has allowed us, on the one hand, to relax the surface structure using the pseudopotential code SIESTA. On the other hand, by using the obtained relaxed structures for calculations within the KKR Green’s function formalism, we have been able to apply SIC and use the magnetic force theorem for calculating Heisenberg exchange parameters. The latter contain information about both the strength of the interaction and the interaction mechanism.

Our calculations show that all three surfaces are magnetic. In addition, we find that applying SIC is necessary to correctly describe the top oxygen atom of the (0001)-t and (0001)-h surfaces.

Thin Me-DLC films with different metal contents have been deposited by ECR-CVD (Electron Cyclotron Resonance Chemical Vapour Deposition). Before the growth process, metal nanoparticles were scattered over the substrate surface by dipping it into a dispersion previously sonicated. The concentration of the dispersion (150, 300, 500 and 5000 ppm) controls the metal content into the carbon coating. The morphology of the deposited samples was analysed by SEM (Scanning Electron Microscopy). The metal content in the carbon films has been evaluated by SIMS (Secondary Ion Mass Spectroscopy). The incorporation of low amounts of metal nanoparticles into the hard carbon coating produces an outstanding improvement in the durability of the layer, as detected by pin-on-disc tests. For an optimum chromium content of 300 ppm of nanoparticles in the dispersion, the grown layer exhibits a noteworthy higher wear resistance respect to that of the DLC reference film. More precisely, in this case, the Cr-DLC coating undergoes ten times longer wear process than the reference DLC coating. However, it is important to indicate that in samples grown using more concentrated dispersions (> 300 ppm), a rapid deterioration of the coating is produced and short lifetimes have been detected, attributed to the large contribution of metal to the transfer layer.

In the present study, the strengthening effect of nano-scale twins in body-centered cubic (bcc) crystal was evaluated using micro-sized cantilever type specimen which contained the nanotwinned region (midrib) in ferrous lenticular martensite. The SEM observations of the micro-sized specimen after bending deformation indicated that midrib can act as barriers against dislocations, resulting in slip localization and non-localization across midrib. The load-displacement curve obtained by bending test showed that twin boundaries significantly enhance the critical resolved shear stress of bcc.

Mineral samples of varying petrology, exposed to ion irradiation and subsequently immersed in water or exposed to a humid environment, show up to 60% depletion of specific surface atoms (Mg, Ca, K, and Na) — a depletion that is enhanced 26,000x compared to unirradiated surfaces. Surface depletions of irradiated minerals exposed to water were measured using X-ray photoelectron spectroscopy. Irradiations were performed with 4 keV Ar+ ions at fluences from 1014 – 1019 ion cm-2; samples were subsequently exposed to liquid water or humid air (35º C and 70% RH). Analyses were done before irradiation, after irradiation, and after exposure to water, allowing identification of changes in composition due solely to ion irradiation or combined with water exposure. Before water exposure, we observe no significant change in stoichiometry of the minerals for ion fluences <1018 ions cm-2. We find incongruent depletion of 60% Mg for forsterite after exposure to humidity or three minutes (or more) water immersion. Augite undergoes reduction in the surface concentration of approximately 30% Mg, 40% Ca, and 55% Na after 1.9 x 1017 Ar cm-2 and immersion in HPLC water (pH: 6.8) for three minutes. Depth profiles of the irradiated, water exposed, minerals show that the depth of the depleted region is on the order of the ion range, ~15nm. In addition, preliminary results for albite, anorthoclase, and microcline in water show significant depletions of Na, Na and K, and K, respectively, from the mineral surface.

Ambipolar top-gated field effect transistors (FETs) based on large area Cu catalyzed CVD-grown monolayer graphene interfaced to advanced dielectrics have been constructed and examined both for their material and electrical qualities. Interfacing of the graphene with novel insulators/substrates could be tailored for the particular application and provide for enhanced device functionality. In contrast to graphene FETs using SiO2-based top-gate dielectric, which show asymmetric electron/hole mobility (with larger hole mobility), and Dirac point shifted to positive levels, FETs constructed using advanced AlN show Dirac point almost near neutral levels and near symmetric electron/hole mobility. The DP is shifted likely due to compensation of the intrinsic p-type doping by n-type doping introduced by the AlN deposition and potentially via a contribution of polarization-induced carrier density. Finally, we demonstrate a top-gated graphene FET with the first observation of RF operation with GHz cut-off frequency based on large area CVD graphene.

Thermoelectric (TE) properties of erbium-silicon co-doped InxGa1-xN alloys (InxGa1-xN: Er + Si, 0≤x≤0.14), grown by metal organic chemical vapor deposition, have been investigated. It was found that doping of InGaN alloys with Er atoms of concentration, N[Er] larger than 5x1019 cm-3, has substantially reduced the thermal conductivity, κ, in low In content InGaN alloys. It was observed that κ decreases as N[Er] increases in Si co-doped In0.10Ga0.90N alloys. A room temperature ZT value of ~0.05 was obtained in In0.14Ga0.86N: Er + Si, which is much higher than that obtained in un-doped InGaN with similar In content. Since low In content InGaN is stable at high temperatures, these Er+Si co-doped InGaN alloys could be promising TE materials for high temperature applications.

The present work reports on the defect-selective etching (DSE) for estimating dislocation densities in icosahedral boron arsenide (B12As2) crystals using molten potassium hydroxide (KOH). DSE takes advantage of the greater reactivity of high-energy sites surrounding a dislocation, compared to the surrounding dislocation-free regions. The etch pits per area are indicative of the defect densities in the crystals, as confirmed by x-ray topography (XRT). Etch pit densities were determined for icosahedral boron arsenide crystals produced from a molten nickel flux as a function of etch time (1-5 minutes) and temperature (400-700°C). The etch pits were predominately triangle shaped, and ranged in size from 5-25μm. The average etch pit density of the triangle and oval etch-pits was on the order of 5x107cm-2 and 3x106cm-2 (respectively), for crystals that were etched for two minutes at 550°C.

It is well-known that cadmium and its corrosion product (cadmium oxide) are carcinogenic and toxic. Consequently, efforts to eliminate cadmium from original equipment and repair processes have been on-going. One potential replacement is indium, which is a soft post-transition metal, whose primary use is in the form of indium tin oxide, e.g., in liquid crystal displays (LCDs). The semi-conductive properties of indium oxide alloys make it possible to use these for cadmium brush plating replacement in applications where contact resistance and impedance are critical parameters. Critical requirements of an alternative to cadmium brush plating in a corrosive industrial atmosphere are (1) be sacrificial to mild steel and (2) provide good electrical conductivity. Cadmium oxide remains semi-conductive, while most other pure metal oxides are electrical insulators, such as aluminum oxide, nickel oxide, and zinc oxide, and therefore, fail in meeting the requirement for bonding and grounding. Similar to cadmium oxide, indium oxide is semi-conductive, but indium exhibits other properties such as cold welding. This paper discusses indium- electroplating approaches to overcome the insulating limitation of pure metal plating and to replace cadmium brush plating. Test results are given for the brush-plated indium-tin alloy as compared to cadmium brush plating and conclusions on such replacement feasibility are provided.

An amorphous silicon (a-Si:H) photoconductor array with two distinct integrated amorphous silicon carbon alloy (a-SiC:H) high pass filters is used to detect two of the cell intrinsic fluorophores. The cutoff wavelength of the filters is tuned by the carbon content in the film. The fluorophores of interest – reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are indicative of the redox state of the cells. Concentrations down to 1 μM for NADH and 50 μM for FAD were detected.

A computational technique is developed to predict the statistics of internal elastic fields of three-dimensional dislocation systems in deforming crystals. The internal elastic fields are computed based on 3D dislocation realizations generated by the method of dislocation dynamics simulation. Preliminary results are presented for the statistical characteristics of the elastic strain, lattice rotation and dislocation density tensor fields. The importance of the current analysis is discussed in the context of direct comparison of simulations with spatially resolved 3D X-ray microscopy measurements of lattice rotation and the dislocation density tensor.

Structural colors were obtained by the deposition of plant cell walls biopolymers films on reflective support. Multilayered xyloglucan(XG)/cellulose nanocrystals(CN) thin films were obtained by spin-assisted layer-by-layer assembly while arabinoxylan (AX) thin films were elaborated via the spin-coating of AX/melamine formaldehyde resin followed by a cross-linking step. The effects of aqueous solutions on the stability of the structural colors were evaluated. The films were subsequently used to detect cellulase and xylanase activities by the change in the colors due to the film degradation. This enzymatic assay method appeared to be about 150 more sensitive that a standard method. Moreover due its simplicity, the method could be used to detect other biomass-hydrolyzing enzymes and more generally for other heterocatalytic degradations of solid polymer layers.

Biomolecules rich in aspartic acid (Asp) are known to play a role inbiomineral morphology and polymorph selection, and have been shown togreatly enhance the growth kinetics of calcite. The mechanism by which thesecompounds favor calcification may be related to their effects upon cationsolvation. Using molecular dynamics, we investigated the influence of smallcarboxylated molecules on the hydration states and water exchange rates ofdivalent cations. We show that the carboxylate moieties of Asp promotedehydration of Ca2+ and Sr2+ and that contact ion pair(CIP) formation is not required to disrupt the hydration of these cations. Ca2+- Asp and Sr2+ - Asp CIP formation decreasesthe total inner sphere coordination from an average of 8.0 and 8.4 in bulkwater to 7.5 and 8.0, respectively. Water residence times estimated for Mg2+, Ca2+and Sr2+ follow the expectedtrend of decreasing residence time with increasing ionic radius. In thepresence of Asp, both solvent-separated ion pair (SSIP) and CIP formationdecrease the residence times of Ca2+and Sr2+ innersphere water molecules. Comparable impacts on Mg2+ hydration arenot observed. Mg2+ - Asp CIP formation is energeticallyunfavorable and Asp does not affect Mg2+ inner sphere waterresidence times.

Two different types of ferroelectric/semiconductor heterostructures, made up of Pb(Zr,Ti)O3/ZnO and BiFeO3/ZnO respectively, were fabricated on Pt(111)/Ti/SiO2/Si(100) by sol-gel process. Obvious diodelike behavior were observed in BiFeO3/ZnO heterostructures when current-voltage characteristics were measured, while Pb(Zr,Ti)O3/ZnO heterostructures exhibited a symmetrical behavior. It is found that Pb(Zr,Ti)O3/ZnO heterostructures showed a large polarization and the remnant polarization was approximately 15μC/cm2. The remnant polarization performed a modulation on the channel resistance. The different properties of two heterostructures might lead to different applications.

High resolution transmission electron microscopy in combination with geometric phase analysis is used to investigate the interface misfit dislocations, strain relaxation, and dislocation core behavior versus the surface treatment of the GaAs for the heteroepitaxial growth of GaSb. It is pointed out that Sb-rich growth initiation promotes the formation of a high quality network of Lomer misfit dislocations that are more efficient for strain relaxation.

The temperature dependence of yield stress and the associated dislocation dissociation in L12 intermetallic compounds are investigated in order to check the feasibility of the classification of L12 intermetallic compounds so far reported in terms of the planarity of core structures of partial dislocations with b = 1/2<110> and 1/3<112> on {111} and {001} glide planes. In contrast to what is believed from the reported classification, the motion of APB-coupled dislocations is proved to give rise to the rapid decrease in yield stress at low temperatures for Co3Ti and Co3 (Al,W). The temperature dependence of yield stress at low temperatures is newly interpreted in terms of a thermal component of solid-solution hardening, at least, for these two L12 compounds. We have proposed a new way to describe the yield stress–temperature curves of L12 compounds with three parameters (the athermal and thermal components of solid-solution hardening and the anomalous strengthening component) when the dislocation dissociation scheme is of the APB-type.

With the aim of investigating fundamental properties and nano-imprintabilities of glassy alloy in the film form, Zr49Al11Ni8Cu32, Pd39Cu29Ni13P19 and Cu38Zr47Al9Ag6 alloy thin films were fabricated on Si substrate by a magnetron sputtering method. These thin films exhibit distinct glass-tradition phenomenon and large supercooled liquid region of about 80 K, confirming as a glassy structure and have very smooth surface and sufficient hardness to maintain imprinted shape, which are suitable for nano-imprint processing. Moreover, thermal nano-imprintabilies of these obtained films are demonstrated by using a dot array mold with a dot diameter of 90 nm and a pitch of 180 nm. Surface observations revealed that periodic nano-hole arrays were successfully imprinted on the surface of these films and precisely corresponded to the periodic dot pattern of the mold. Particularly, Pd-based glassy alloy thin film indicated more precise pattern imprintability, namely, more flat residual surface plane and sharper hole edge. These results suggest that these glassy alloy thin films, especially Pd-based glassy alloy thin film have high potential for application to the nano-imprinting materials.

The room-temperature dependences of the electrical conductivity σ, Seebeck coefficient S, Hall coefficient RH, and the thermoelectric power factor P on the thickness (d=10–300 nm) of the thin films grown on mica substrates by thermal evaporation in vacuum of Bi-Sb solid solutions crystals with 4.5 at.% Sb were obtained. It was established that an increase in d up to ~ 200 nm leads to a change in kinetic coefficients and that in the thickness dependences of the thermoelectric properties, quantum oscillations were observed. It was shown that the monotonic component of the σ(T) dependence can be satisfactorily approximated by theoretical calculations based on the classical Fuchs - Sondheimer theory. The theoretically estimated period of oscillations is in a good agreement with the experimentally observed period.

A recent approach in disease diagnosis and viral epidemics is aimed atpoint-of-care tests that could be administered near the patient rather thantime-consuming processes involving centralized laboratories. Point-of-caredevices provide rapid results in simple and low-cost manner requiring onlysmall sample volumes. These devices will strongly benefit from advancedmaterials and fabrication methods to improve their efficiency andsensitivity. We report a functionalized carbon nanotube label for animmunosensor application. Carbon nanotube label was prepared by modifyingthe carbon nanotube surface to anchor biomolecules. First, the carboxylicacid treated multi-walled carbon nanotubes (MWCNTs) were uniformly dispersedwith polyvinylpyrrolidone (PVP) by sonication in aqueous solution. PVPpartially wraps around the carbon nanotubes and exposes the surface of thenanotubes for further functionalization. The MWCNTs were then conjugatedwith human immunoglobulin G (IgG) using EDC/Sulfo-NHS coupling chemistry,where the antibodies occupied sites not covered by PVP. The dispersion,surfactant modification, and antibody conjugation of the MWCNTs were alsoconfirmed using SEM and TEM images. The successful functionalization of theMWCNTs and reactivity of the covalent attached antibodies were demonstratedfor specific antigen binding on the microelectrode device. The carbonnanotube-based detection mechanism could be tailored for screening variousanalyte specific molecules. Furthermore, the reported technique could easilybe integrated in various microfluidic and lab-on-a-chip devices for thedevelopment of functional electronic sensors providing quantitative,sensitive, and low-cost detection in pointof- care setup.

Porous scaffolds of alkaline-soluble collagen including nanocompositeparticles of chondroitin sulfate and low crystalline hydroxyapatite forcartilage regeneration were fabricated by freeze-drying and thermaldehydration treatments; porous collagen scaffolds were also synthesized as areference. The scaffolds were cross-linked using glutaraldehyde (GA) vaportreatment in order to enhance biodegradable resistance. Microstructuralobservation with scanning electron microscope indicated that the scaffoldswith and without GA cross-linkage had open pores between 130 to 200 μm indiameter and well-interconnected pores of 10 to 30 μm even aftercross-linkage. In vitro biodegradable resistance tocollagenase was significantly enhanced by GA cross-linking of the scaffolds.All these results suggest that the GA cross-linked scaffolds consisting ofcollagen, chondroitin sulfate, and low crystalline hydroxyapatite havesuitable microporous structures and long-term biochemical stability forcartilage tissue engineering.

In the Bi2O3-MO-P2O5 diagram, on the basis of previous compounds based on 2D-ribbon like units, we have predicted and prepared the infinite term. It contains [Bi2O2]2+ planes arranged within a never-observed crystallographic form. In this series, the ribbons-like units are polycations built on the linkage of n O(Bi,M)4 tetrahedra along their width and infinite in a perpendicular dimension. Hence, this novel form completes the continuous series of analogue compounds, whose building units now extend from the single chain to the infinite plane, via a number of discrete n values (2,3,4,5,6,7,8,9,10,11). The presented materials of formulae Bi4MP2O12 (M= Zn and Mg) roughly show the same crystal structure. However different arrangements of the groups located between the [Bi2O2]2+ planes are at the origin of a complex superstructure in the case of the zinc compounds.