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We report on detailed study of detonation nanodiamonds (DNDs) whose surface has been chemically modified by copper with the aid of ion exchange in water DND suspension. High resolution transmission electron microscopy, Raman, IR, electron magnetic resonance (EMR), nuclear magnetic resonance (NMR), and superconducting quantum interference device techniques were used for the characterization of DND. Carboxyl groups, appearing on the surface of a nanodiamond particle during its synthesis and purification processes, provide an effective binding of divalent copper ions to the surface. The binding results from the ion exchange between metal cations and protons of surface carboxyl groups in water solutions. IR data evidence the presence of multiple C[Single_Bond]O[Single_Bond]C groups in the dried copper-modified DND product. Both EMR and 13C NMR provide direct evidences of the appearance of isolated Cu2+ ions on the surface of the 5 nm nanodiamond particles. EMR spectra reveal well-pronounced hyperfine structure due to 63,65Cu nuclear spin I=3/2 with the spectral pattern which is typical for mononuclear axially distorted Cu2+ complexes in polycrystals. Using Cu2+ ions as paramagnetic probes two-component model of carbon inherited paramagnetic centers in DND is suggested. Magnetic susceptibility for all samples follows the Curie–Weiss law above 30 K. The concentration of magnetically observable copper ions Cu2+ (spin S=1/2) localized on the nanodiamonds surface increases up to approximately 1.5–3.5 ions per nanoparticle with increasing concentration of copper acetate in starting solutions. [ABSTRACT FROM AUTHOR]

Three types of dissociated misfit dislocations (MDs) in epitaxial Ba0.3Sr0.7TiO3 thin films grown on (001) LaAlO3 have been studied by high-resolution transmission electron microscopy. First, a MD with b=[101] dissociates into two edge partials and results in the incline of film lattice. Second, a [110] MD is split into two (1/2)[110] partials of mixed character. In the third case, a [110] MD of mixed character is composed of three partials which are reacted with two (1/2)<110> stacking faults. Neither of the three types of dissociation reactions has been reported before for MDs in perovskite thin films. [ABSTRACT FROM AUTHOR]

Stacked AA graphite has been synthesized using a high-density dc plasma in hydrogen-methane mixtures. Graphene layers have been grown epitaxially with 2-1 registration between the AA graphitic edges and the (111) surface of diamond. In addition, a new graphite crystal structure containing AA′ graphene layers, where alternate planes are translated by half the hexagon width, is formed by 1-1 registry. The resulting interplanar distances of the AA graphite at the interface range from 2.20 Å for the 1-1 registration to 4.40 Å for the 2-1 registration and have been measured directly by high-resolution transmission electron microscopy (TEM). The appearance of the characteristic d-spacings, 3.55, 2.15, 1.80, 1.75 (not fully resolved), and 1.25 Å in the selective area diffraction patterns from the TEM, are consistent with reflections from the (001), (100), (102), (002), and (110) planes of the AA graphite. Simulation of the diffraction patterns, employing the structural factors of graphene, confirms the existence of AA graphite. [ABSTRACT FROM AUTHOR]

Nanoparticles with various compositions of Fe–Rh have been fabricated by a solution phase chemical method and their magnetic properties characterized. After refining and size selection, the average particle size is about 2–5 nm by high-resolution transmission electron microscopy observation. From x-ray diffraction results, as-deposited FeRh nanopaticles reveal a typical chemically disordered fcc structure which can be transformed into CsCl-type structure through thermal annealing. Under selected annealing conditions, the coercivities, Hc, for FeRh nanoparticles measured at room temperature are increased, compared with that of their as-deposited states. This increasement in Hc is due to the crystallization of CsCl-type structure after annealing. Nanoparticles of Fe36Rh64 and Fe38Rh62 annealed at 600 °C for 6 h show the presence of the magnetic phase transitions, while those of Fe75Rh25 particles did not exhibit such a transition. [ABSTRACT FROM AUTHOR]

SiC nanotubes have been synthesized under hydrothermal conditions. Research results show that SiC nanotubes consist of hollow inner pore, crystalline SiC wall layers, and thin amorphous silica sheath. Besides most abundant normal nanotubes, bamboo-shaped SiC nanotubes and elliptically hollow SiC nanospheres were also observed. The different morphologies of the SiC nanotubes are closely relative to the diameter of the SiC nanotubes. The confinement effect of other SiC nanotubes may play an important effect retarding the growth of SiC nanotubes to form the hollow SiC nanospheres. Defect inducing growth is proposed to explain the formation of bamboo-shaped SiC nanotubes. [ABSTRACT FROM AUTHOR]

Silicon nitride (Si3N4) is known to offer the required adhesion to chemically vapor deposited diamond coatings for demanding mechanical solicitations but the nature of their strong interface is not well know. Focused ion beam preparation preserved such thin layer for high resolution transmission electron microscopy. Contrarily to earlier suppositions, SiC interlinking particles were not found. Instead, the interface shows diamondlike carbon interlayers (approximately 3nm in thickness) intercalated with regions of directly-grown nanomicrometric and submicrometric-diamond crystals. A grain-to-grain epitaxial relationship of the type <111>Dia∥<010>Si3N4 and {111}Dia∥{120}Si3N4 is observed, concomitant with a 7:1 match arrangement, which assists on the interface strength. [ABSTRACT FROM AUTHOR]

The origin of multilevel resistances of In3Sb1Te2 (IST) phase-change random access memory cell has been investigated with high-resolution transmission electron microscopy (HR-TEM). The HR-TEM indicates that the microstructure of IST in the programming volume changes from amorphous to InSb and amorphous at the first state, and InSb and InTe at the second state, and IST at the third state, which are fairly consistent with four different levels of resistance. The resistance difference between the amorphous and the IST is about four orders of magnitude. [ABSTRACT FROM AUTHOR]

Three dimensional atom probe tomography coupled with high resolution transmission electron microscopy were used to analyze the structural and compositional transitions across interfaces of Ti Ohmic contacts on SiC. The results conclusively show that during the interfacial reaction carbon diffuses into the Ti layer, with the reaction zone extending beyond the immediate interface. The resultant TiC/TiCx interfacial layer provides a graded work function profile between the Ti and SiC, and facilitates low contact resistance which was measured by the transmission line, current-voltage method. [ABSTRACT FROM AUTHOR]

We report on a method to measure the mean inner potential (V0) using transmission electron microscopy. It is based on phase retrieval from a focus series and has allowed to measure V0 as a function of the size for a system of gold nanoparticles. It comes out that V0 increases for particles below 2 nm. The focus series being carried out in conditions close to the high-resolution ones, structural information can be directly obtained. The high-resolution images have revealed that significant structural change occurs below the 2 nm size, which should be related to the V0 increase. [ABSTRACT FROM AUTHOR]

Nanoscale deformation in TiC/a-C nanocomposite coatings is revealed by combined nanoindentation and high resolution cross-sectional transmission electron microscopy. A process characterized by rearrangement of TiC nanocrystallites and the displacement of a-C matrix is found to dominate the deformation mechanism at length scales ranging from tens of nanometers down to 1 nm and contributes to toughening of the nanocomposite coatings by delocalizing local plastic deformations. [ABSTRACT FROM AUTHOR]

Shallow (Rp∼20 nm) As and B-doped layers in (100) silicon, formed by low-energy ion implantation, have been investigated using conventional and high resolution transmission electron microscopy before and after either electron beam or furnace annealing. After annealing residual defects were observed in the region beyond the original amorphous/crystalline interface for both As and B implants and the nature of these defects and their stability was found to be relatively insensitive to a variety of annealing conditions. Lattice images of 10-keV As-implanted material indicated that a continuous amorphous layer was formed after implantation which regrew into perfect single crystal following electron beam processing for 1 s with a peak temperature of 900 °C. [ABSTRACT FROM AUTHOR]

It has been recently found by energy filtered transmission electron microscopy (EFTEM) that metastable SiOx≈1 films decay into a Si nanowire network embedded in SiO2 by spinodal decomposition during thermal treatment. To have a guideline for nanocomposites fabrication, details of the morphology evolution have been studied by comparison of EFTEM images with kinetic Monte-Carlo (kMC) simulations. Pair correlation functions calculated by kMC have been adjusted to that extracted from EFTEM. This comparison leads to the conclusion about characteristic lengths of 3D morphologies. Combining kMC with EFTEM delivers the understanding for tailoring the properties like quantum confinement of the spongy Si. [ABSTRACT FROM AUTHOR]