Using chemical vapor deposition technique, a novel 3D carbon nano-architecture called a pillared graphene nanostructure (PGN) is in situ synthesized. The fabricated novel carbon nanostructure consists of CNT pillars of variable length grown vertically from large-area graphene planes. The formation of CNTs and graphene occurs simultaneously in one CVD growth treatment. The detailed characterization of synthesized pillared graphene shows the cohesive structure and seamless contact between graphene and CNTs in the hybrid structure. The synthesized graphene-CNT hybrid has a tunable architecture and attractive material properties, as it is solely built from sp2 hybridized carbon atoms in form of graphene and CNT. Our methodology provides a pathway for fabricating novel 3D nanostructures which are envisioned for applications in hydrogen storage, nanoelectronics, and supercapacitors.

Using Scanning Spreading Resistance Microscopy and direct current-voltage measurements, a long-relaxation transport current in polycrystalline PZT films is shown to depend on the polarization direction and voltage rise rate, the latter is typical for a capacitive current. The clockwise current hysteresis is observed at any polarization of the film. We suppose that the long current relaxation is due to recharge of traps, which participate in screening of polarization charges on PZT grain boundaries. The polarization charges response to applied bias for a short time, whereas the traps response to variation of the polarization charges takes much longer time.

We measured the surface free energy of a substrate by transmission electron microscopy (TEM) using sub-millimetre-sized inkjet droplets. By employing two types of TEM grids with different surface free energies, we investigated the relationship between the surface energy and the patterns of an organic solution dried on the grids. We confirmed that the generation of the porphyrin hexamer [(H2PAC15)6TPh] patterns was affected by the surface free energy of the TEM grid.

We have developed material (Bi0.7Dy0.3FeO3)(BDFO) which exhibits the multiferroic behavior at room temperature with significant coupling in bulk as well as thin films. If these properties could be fashioned in nano rods, implementation in devices could be certainly more prominent and straight forward. We have therefore used vertically aligned arrays of silicon rods (~5 μm in length and ~ 500 nm in diameter) as base material to direct the growth of BDFO in rod form. BDFO is deposited on the surface of Si rods by using pulsed laser deposition technique. These BDFO/Si rods are then separated from the support, dispersed into propanol and transferred onto SiO2/Si substrates for testing. X-ray diffraction (XRD) results indicate presence of phase pure BDFO layer on Si rods. Saturation observed at room temperature in magnetic and ferroelectric hysteresis loops confirm the coexistence of ferromagnetic and ferroelectric properties. Change in ferroelectric polarization measured on single rod in the presence of applied magnetic field suggests the coupling behavior between two order parameters. Moreover, change in magnetic domain pattern of BDFO rods associated with applied electric field further supports the presence of coupling behavior in both ways. The vertical and lateral displacement occurring in BDFO/Si rods with applied electric field helps to confirm their piezoresponce behavior. BDFO/Si nanorods with multifunctional properties could find variety of novel device applications with flexibility and simplicity in operation. It might include single rod power generation by means of applied stress or magnetic field.

The layered oxide LiVO2 recently has received more attention due to its interesting structural and magnetic behaviors involving the two-dimensional magnetic frustration in these systems. We synthesized a series of F-doped LiVO2 samples, and reported the F-doping effect on the structure and transition temperature Tt . The samples LiVO2-x Fx (x=0, 0.1, 0.2 and 0.3) were characterized by X-ray diffraction, scanning electron microscope (SEM), differential scanning calorimetry (DSC), magnetic susceptibility and specific heat measurement. The structural analysis shows that with increasing x, the ratio of lattice parameter c/a increasing, i.e. in the a-b plane the lattice is compressed while in the c-axis direction the lattice expands. The DSC measurements show that a first-order phase transition happens at around 500 K, and the thermal hysteresis around phase transition temperature Tt increases with increasing x. Substitution of O with F ions results in a change of two dimensional characteristics and the distortion of the VO6 block in structure, which significantly influence the magnetic ordering transition temperature Tt .

Titanium aluminide based alloys are candidate materials for high temperature structural applications. They are typically alloyed with elements such as Nb, Ta, Mo, Cr and B for property enhancement. To understand the relationship between microstructure and alloy composition/processing condition, detailed models of phase equilibria in multicomponent Ti-Al based alloys are needed. In this work, we developed thermodynamic models for the phases in the Ti-Al-Cr system based on critically assessed binary models and ternary experimental data in literature, using the CALPHAD approach. Isothermal sections at 1200, 1150, 1000 and 800°C, and the liquidus projection, were calculated from the currently developed thermodynamic models; these are in satisfactory agreement with experimental data. Isopleths were calculated at specified Cr concentrations, and solidification paths were simulated under the Scheil conditions for a range of Ti-Al-Cr alloys. From the calculated phase diagrams and solidification paths, the effect of Cr on the microstructure of Ti-Al alloys can be understood.

Effects of shot peening on fatigue properties of Zr-based amorphous matrix composite containing ductile crystalline particles were investigated, and fatigue processes were analyzed and compared with those of an as-cast composite. The microstructural analysis results of the shot-peened composite surface indicated that the deformation and surface flexion were observed as the shot-peening time or pressure increased. The compressive residual stress formed on the shot-peened surface was about the half of the ultimate tensile strength, and was not varied much with shot-peening time or pressure. The fatigue limit and fatigue ratio of the shot-peened composite were considerably higher than those of the as-cast composite. This was because the compressive residual stress formed by the shot peening induced the initiation of fatigue cracks at the specimen interior, instead of the specimen surface, thereby leading to the enhanced fatigue limit and fatigue life.

Surface photovoltage of three-dimensional networks composed of fused indium phosphide (InP) nanowires is discussed. Particular emphasis is given to the dependence of surface photovoltage on the chopping frequency of light that excites the nanowire network as observed in regions which are laterally separated from the excitation. The nanowire network is modeled as a thin film to simplify numerical solutions to transport equations which aids in the interpretation of diffusion and drift of photo-generated carriers within the nanowire network.

The potential of MgO and ZrO2 as catalytically active substrates for graphene formation via thermal CVD is explored. Experimental observations show the growth of single and multi-layer graphene nano-flakes over MgO and ZrO2 at low temperatures. The graphene nano-flakes are found to anchor at step sites. Ab initio calculations indicate step sites are crucial to adsorb and crack acetylene.

We have determined critical parametres that restrict the vapor→liquid drop→solid growth of silicon NWs. We demonstrate that there are maximum and minimum critical radii for NW growth and identify boundary conditions that lead to solvent droplet breakdown and crystal branching.

Magnetization behavior of Nd9(Fe, B)87Zr2Nb2 nanostructure magnets have been investigated. We will show that the nanostructure magnets are composed of magnetic clusters of exchange-coupled single domains and the coercivity is governed by coupling intensity between soft and hard magnetic clusters in the magnets.

ZnO nanostructures have attracted a great deal of interest because of their biocompatibility and outstanding optical and piezoelectric properties. Their uses are widely varying, including incorporation in sensors, solar cells, and nanogenerators. Biological systems are yet another area of application of ZnO nanowires. Apart from their electrical and optical properties, ZnO nanostructures can be used for the mechanical reinforcement of existing biomimetic scaffolds such as collagen and/or other biodegradable polymers (poly(lactic acid), polyglycolide, poly(alkyene succinate)s or polyhydroxylalkanoates). In this work, we have demonstrated a cheap and comparatively facile hydrothermal growth method for the bulk production of ZnO nanostructures exhibiting an aster-like geometry. The novel nanostructures of ZnO can be used as reinforced material to biopolymers. The aster shape has presented an increased surface area, providing a means for enhancing the stabilization of the gels and\or polymers. With controllable growth of ZnO nanostructures this method allows the geometry which could be tuned for maximal coupling between the two phases of composite and increased mechanical strength.

The α-polymorph of Li3FeF6 has been prepared from aqueous-based solution by precipitation under different conditions to obtain small particles. Several alcohols have been used to vary the precipitation media. Among them 2-propanol has been found to provide particles of about 100 nm under controlled conditions of temperature and H2O: R-OH volume ratio. The average particle size of some of the as-prepared samples is smaller than that obtained for those samples obtained by precipitation in water. However, the expected enhancement of electrochemical performances does not occur for the as-prepared samples. Inserted amount of lithium into the cryolite structure of Li3FeF6 increases significantly only when composites of asprepared Li3FeF6 and carbon are milled mechanically. For example 12h milling is needed to reach 64 mAh/g (45% of theoretical capacity).

We propose the use of amine-rich polyelectrolyte multilayers as a versatile, high quality, tunable adhesive surfaces for biomedical and nanotechnological applications. The films are simple to fabricate under mild conditions and provide at least as good adhesion as standard aminopropyltriethoxysilane terminated glass substrates. In addition, the multilayer surface can be reliably passivated by acetylation with acetic anhydride which reduces the adhesion to the point that non-specific binding of proteins and nanoparticles becomes all but negligible. We demonstrate that this property, in combination with the robustness of the film, makes it possible to pattern the adhesiveness of the film at the nanoscale level.

We briefly review our data on MOCVD growth problems of sandwich stacked heterostructures based on Bi-Sr-Ca-Cu-O and YBa2Cu3O7 high temperature superconductors. Non-superconducting layers were (Ca, Sr)CuO2, (Ca, Ba)CuO2 and Bi4Ti3O12. Structures were with c-axis normal or inclined with about 45° vs. the surface of the substrate. Film-substrate lattice relationship, growth mechanism and the resulting morphology controlling roughness and uniformity, stability domain of the phases and inter diffusion are all important aspects toward significant progress in the field. Our analysis indicates that requirements are more severe for non-c-axis heterostructures, and suggest some ideas for further improvements.

We have performed a detailed analysis of the magnetic (collinear and noncollinear) order and atomic and electron structures of UO2, PuO2 and UN on the basis of density functional theory with the Hubbard electron correlation correction (DFT+U). We have shown that the 3-k magnetic structure of UO2 is stabilized for the Hubbard parameter value of U=4.6 eV (while J=0.5 eV) when Dudarev’s formalism is used. UO2 keeps cubic shape in this structure. Two O atoms nearest to each U atom in direction of its magnetic moment move toward this U atom. Neither UN nor PuO2 shows the energetical preference for the rhombohedral distortion, in contrast to UO2, and, thus, no complex 3-k magnetic structure in these materials. Both materials have the AFM tetragonal <001> structure at reasonable choice of parameters U and J.

In this work, a room temperature spin-polarized LED based on ferromagnetic Ga1-xGdxN is reported. The device was grown by metalorganic chemical vapor deposition (MOCVD) and is the first report of a spin-LED based on Ga1-xGdxN. Electroluminescence from this device had a degree of polarization of 14.6% at 5000 Gauss and retained a degree of polarization of 9.3% after removal of the applied magnetic field. Ga1-xGdxN thin films were grown on 2 μm GaN templates and were co-doped with Si and Mg to achieve n-type and p-type materials. Co-doping of the Ga1-xGdxN films with Si produced conductive n-type material, while co-doping with Mg produced compensated p-type material. Both Si and Mg co-doped films exhibited room temperature ferromagnetism, measured by vibrating sample magnetometry.

A facile anodic electrophoretic deposition (EPD) process has been developed to prepare thin uniform films consisting of titanate nanotubes (TNTs) that were synthesized by a hydrothermal approach. Such an EPD process offers easy control in the film thickness and the adhesion to the substrate was found to be strong. The chemical composition and structure of the products have been characterized by HRTEM, FESEM, XRD and TG/DTA. It was found that the functionalization of TNTs plays a key role on the electrolyte stability and the successful formation of a uniform TNT film with good adhesion. The as-prepared TNT films show exceptional superhydrophilic behavior with ultra-fast spreading, while it converts to superhydrophobicity yet with high adhesion after 1H,1H,2H,2H-perfluorooctyl-triethoxysilane modification. This study provides an interesting method to prepare films with extremely high wettability contrast that are useful for producing different kinds of functional materials.