It was found that after treatment under 10T magnetic field and temperature 900 °C the bending strength of NiAl–Cr(Mo)–Hf alloy is increased by about 75%. The fracture section observation shows that the specimens' ductility is enhanced by the magnetic field treatment. Electron probe microanalysis shows that after treatment of the magnetic field the Heusler phases at NiAl/Cr(Mo) grain boundaries are partially dissolved and the small Heusler phases particles at Cr(Mo) and matrix phases interfaces almost dissolved into NiAl matrix.

Controlling the characteristics of nanowires in order to later construct nanoarchitecture and nanocomponents for nanodevice and nanosensor applications is essential. Metal oxide nanowires are aligned using the Langmuir-Blodgett (LB) technique to uniaxially compress the nanowires. A surfactant monolayer of metal oxide nanowires is fabricated, and then compressed on an aqueous subphase. The compression yields an array of aligned nanowires, which is transferred to a planar substrate. Cutting areas of the array are defined by electron beam nanolithography. After an etching process, it is shown that the metal oxide nanowires have been successfully cut. With further refinement of this technique, the nanowires can be used to construct basic building blocks of nanodevices and nanosensors.

A variety of semiconductor and metal nanoparticles can be synthesized and tunable in size from about 10 to 200 Å using size-selective separation technique. Preparation of monodisperse samples enables systematic characterization of the structural, electron, and optical properties of materials as they evolve from molecular to bulk in the nanometer size range. Sample uniformity makes it possible to manipulate nanocrystals into close-packed, glassy and ordered nanocrystal. At inter-particle separations 5-100 Å, dipole-dipole interactions lead to energy transfer between neighboring nanocrystals, and electronic tunneling between proximal nanocrystals gives rise to dark and photoconductivity. The fabrication of monodisperse ordered nanoarrays with the inter-particle separations less than 5Å will be very important to study its physical properties since interaction between neighboring nanocrystals cause otherwise insulating assemblies to become semiconducting, metallic, or superconducting depending on nanocrystals composition. Here we present the fabrication of monodisperse PbSe nanoarrays with inter-particle distance less than 5 Å and its nanostructure study.

Three dimensional Ni and NiO inverse opal macromeshes were characterized by scanning electron microscope (SEM) and transmission electron microscope (SEM). The octahedral cubes of the macroporous Ni were found mostly grown as single crystals with staking faults and microtwins. There was no preferential growth of these cubes as determined by selected area diffraction pattern (SADP). Some NiO nanocrystals with size of about 5 nm were formed on the surface of inverse Ni opal membrane during etching away of silica spheres. The oxidation of Ni mesh turned it into NiO macromesh with grain size of about 20 nm at 550°C. The nanocrystalline NiO mesh is suitable for further fabrication of three dimensional nanobeads. By annealing the meshes at 650°C, the NiO nanograins grew to a size of over 50 nm. This three dimensional ordered macroporous structure with higher temperature treatment is considered as stable and important for further application.

Currently there is a strong interest in fabricating nanoporous metal arrays using various template methods. Porous opal membranes of close-packed silica beads, for example, have a unique template structure due to their tetrahedral and octahedral interstices. Such structures can be infiltrated with a variety of materials, especially metals, to form continuous inverse networks. Interest in these forms comes from their potential application in a variety of areas including photonics, magnetics, catalysis, and thermoelectrics. In this paper, we present electron microscopy characterization of inverse nickel photonic materials prepared by electrodeposition method.

Electrodes were formed from opal pieces (typically 7 x 10 x 1.5 mm with silica spheres about 300 nm) by first depositing about 0.5 micron thick copper films on one side of the piece with magnetron sputtering. A length of wire was then attached to the copper backing with silver paste.

Nanoparticles (1-100 nm) of semiconductors and metals have shown some unique optical, electric and magnetic and catalytic properties which are greatly different from their bulk materials. Recently the use of these nanoparticles as quantum dots in nanoelectronics requires their arrangement in one, two, and three dimensions (1D, 2D and 3D). Therefore more attention has been paid to the organization of these nanoparticles into ordered arrays in order to achieve novel collective properties. Gold colloids have been well studied for its self-organization in several systems. Here we present 1D, 2D and 3D gold self-organization nanostructure generated from reverse micelles (microemulsion system).

Gold nanoparticles were prepared by the reduction of HAuCU in CTAB (cetyltrimethylammonium bromide)/Octane+l-Butanol/H2O microemusion system using NaBH4 as the reducing agent. Typically, 0.3g of CTAB, 0.148ml of 0.056M HAuCl4 aqueous solution, l.Og octane (surfactant) and 0.25g 1-butanol (cosurfactant) were mixed together and stirred vigorously for 10 min until a homogenous phase was obtained.

We are attempting to grow bulk AlN that would be suitable as a substrate for nitride film growth. Bulk AlN films were grown by physical vapor transport on 3.5° off-axis and on-axis 6H SiC seed crystals and characterized by TEM, x-ray-diffraction, Auger electron microscopy, and SEM. TEM images show that the bulk AlN does not have the columnar structure typically seen in AlN films grown by MOCVD. Although further optimization is required before the bulk AlN is suitable as a substrate, we find that the structural characteristics achieved thus far indicate that quality bulk AlN substrates may be obtained in the future.

Artificial defects generated by ion irradiation have been considered an efficient method to enhance the critical current density in superconducting materials. The mechanism of producing defects as flux pining centers is still an important issue since the efficiency of irradiation-induced defects in flux pinning strongly depends on their microstructures. Different types of defects have been found in heavy ion irradiation. However, there are few results that show light ion irradiation due to the target material selected, the type of light ion and energy, and the incident ion angle. Another factor is the difficulty of cross-sectional sample preparation. In this paper, a single crystal Bi2Sr2CaCu2O7-x with 11 MeV B5+ ion irradiation was observed by transmission electron microscope (TEM) from both plan and cross-sectional view.

The Bi2Sr2CaCu2O7-x single crystals used for ion irradiation were prepared using the floating-zone melting method. The crystals were cleaved into thin sheets of about 20 μm thickness along the a-b plane and cut to about 2mmx2mm size.

Gold-coated iron core-shell structure and Au/Fe/Au onion-like nanoparticles synthesized using reverse micelles were characterized by transmission electron microscopy (TEM). The average nanoparticle size of the core-shell structure is about 8 nm, with about 6 nm diameter core and 2 nm shell. The gold shell structure can be resolved from both high resolution electron microscopy (HREM) image and energy dispersive X-ray spectrum (EDS). Even though the gold and iron electron diffraction rings overlap a little bit, they can still be identified due to the slight mismatch of the diffraction rings. The Au/Fe/Au onion-like nanoparticles were also observed. The nanoparticles were formed with about 6 nm diameter gold core, 1 nm iron interlayer and 2 nm gold shell. The shell structure coated on the core appeared unhomogeneous, however, in both cases the iron core and interlayer iron shell stay air-stable.

We are attempting to grow bulk AlN that would be suitable as a substrate for nitride film growth. Bulk AlN films were grown by physical vapor transport on 3.5° offaxis and on-axis 6H SiC seed crystals and characterized by TEM, x-ray-diffraction, Auger electron microscopy, and SEM. TEM images show that the bulk AlN does not have the columnar structure typically seen in AlN films grown by MOCVD. Although further optimization is required before the bulk AlN is suitable as a substrate, we find that the structural characteristics achieved thus far indicate that quality bulk AlN substrates may be obtained in the future.

GaN has been intensively studied because of its potential applications for the fabrication of blue- or ultraviolet-light emitting devices. Sapphire (α-Al2O3) is generally used as the substrate for growth of GaN film. However, the large lattice mismatch between GaN and Al2O3is a possible cause of the large defect density in the GaN films. Consequently, alternative substrates are being studied with the aim of growing films of lesser defect densities and improved opto-electronic properties. In this paper, we report a transmission electron microscopy (TEM) study of a GaN film grown on cubic SiC which has been obtained by carbonization of the top silicon layer of a SIMOX substrate, i.e. the system GaN/SiC/Si/SiO2/Si.

Cross-sectional TEM specimens were prepared by the conventional sandwich technique with the foil surface normal to the Si[l10] direction. The composite sample was ground and dimpled to a thickness of ∼ 10μm, and subsequently ion thinned to electron transparency.