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Spectroscopic investigations of individual single-crystalline GaN nanowires with a lateral dimensions of approximately 30-90nm were performed using the spatially resolved technique of electron energy-loss spectroscopy in conjunction with scanning transmission electron microscope showing a 2-A electron probe. Positioning the electron probe upon transmission impact and at aloof setup with respect to the nanomaterials, we explored two types of surface modes intrinsic to GaN, surface exciton polaritons at approximately 8.3eV (approximately 150nm) and surface guided modes at 3.88eV (approximately 320nm), which are in visible/ultra-violet spectral regime above GaN bandgap of approximately 3.3eV (approximately 375nm) and difficult to access by conventional optical spectroscopies. The explorations of these electromagnetic resonances might expand the current technical interests in GaN nanomaterials from the visible/UV range below approximately 3.5eV to the spectral regime further beyond.

Vertically aligned indium oxide nanowires were grown on a-plane sapphire substrate by the method of catalyst-assisted carbothermal reduction. The morphology and crystal structure of the nanowires are determined by X-ray diffraction, transmission electron microscopy and field-emission scanning electron microscopy. Two types of In 2 O 3 nanowires were found by controlling the growth conditions. The nanowires with a hexagonal cross-section were shown to grow in [1 1 1] direction, whereas those with a square cross-section grow in [0 0 1] direction. In addition to the temperature effects, the concept of supersaturation in Au catalyst is proposed to explain the formation of these two types of nanowires. Besides, tapering, which is explained with the interplay between the vapor–liquid–solid and vapor–solid growth mechanisms, is observed in the nanowires.

Here, we demonstrate that non-dipole allowed d-d excitations in NiO can be measured by electron energy loss spectroscopy (EELS) in transmission electron microscopes (TEM). Strong excitations from (3)A(2g) ground states to (3)T(1g) excited states are measured at 1.7 and 3 eV when transferred momentum are beyond 1.5 A(-1). We show that these d-d excitations can be collected with a nanometrical resolution in a dedicated scanning transmission electron microscope (STEM) by setting a good compromise between the convergence angle of the electron probe and the collected transferred momentum. This work opens new possibilities for the study of strongly correlated materials on a nanoscale.

Recently, interesting differences for ion – uniform film and ion – nanostructure interaction phenomena, particularly relating to ion beam mixing effects have been reported. Upon irradiation with 1.5 MeV Au 2+ ions on isolated Au nanostructures on silicon substrate, a higher probability of crater formation, larger sputtered particle size and its coverage and enhanced sputtering yield compared to the continuous films of Au on Si substrate were observed. Ion bombardment at high flux (≈6.3 × 10 12 ions cm −2 s −1 ) showed a dramatic mass transport from nanostructures extending up to a distance of about 60 nm into the substrate, much beyond their size. In this paper, RBS/Channeling results would be presented to elucidate on the arrangement of re-distributed gold atoms location in silicon and silicide matrix. Scanning transmission electron microscopy (STEM, with high angle annular dark field imaging) was used to complement the RBS results in determining the unusual mass transport and under ion–nanostructure interaction. The amorphous nature of the silicon matrix, that is deduced from both the RBS/Channeling and from TEM measurements, is an important factor in enhanced diffusion process resulting in dramatic mass flow.

It has been common practice for physicists to assume electronic homogeneity when dealing with condensed matter properties. Recent experimental development, which have revealed fascinating properties of complex materials, demonstrate that such extraordinary macroscopic properties are often associated with microscopic-scale electronic/magnetic inhomogeneity, which limits the Hamitonian-type theoretical approach. Herein, we discuss the microscopic coexistence of metallic and insulating phases in novel materials having an intricate interplay among charge/spin/lattice degrees of freedom. Examples include the coexistence of superconducting-metallic and insulating phases in La 2 CuO 4+ δ as well as Mg 1− x B 2 . The insulating nature in La 2 CuO 4+ δ originates from electron–electron correlation, but disorder plays a dominant role in producing the insulating behavior in Mg-deficient Mg 1− x B 2 . We also examine the microscopic coexistence of ferromagnetic-metallic and charge-ordered-insulating phases in mixed-valent manganites, exhibiting colossal magnetoresistance. Possible origins of this electronic phase separation are discussed.

Electron diffraction, magnetic susceptibility and electronic transport indicate the existence of charge-carrier ordering in (La, Sr)2NiO4. This is most pronounced for a hole concentration nh of 1 3 with a superlattice modulation vector δ of 1 3 and it is also suggested for n h = 1 2 with δ = 0 .

Rapid progress has been made on thin films of high-Tc superconducting perovskites. Here we focus on the results from one of the most studied oxide systems, 125 K TlBaCaCuO. We have produced single-phase high-Tc superconducting Tl2Ba2Ca2Cu3O10 films 0.2–1.0 microm thick on MgO(100) and SrTiO3(100) substrates by sputtering using a single oxide target. The Tl2Ba2Ca2Cu3O10 films have a Tc onset at 125K and a Tc(R=0) at 116 K. Transport critical current densities of these films on SrTiO3 substrates are as high as 105 A cm−2 at 100 K. These thallium-based films are not only strongly textured with the c-axis perpendicular to the film plane, but also epitaxial to SrTiO3(100) substrates.