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To transform a monocrystalline diamond into monocrystalline graphite, the exposure of an ultrafast laser to a (111) diamond face was investigated for the first time. The single pulse of the third harmonic of a Ti:sapphire laser (100 fs, 266 nm) was used to produce graphitized inclusions embedded in a (111) diamond substrate. Three different regimes of (111) diamond graphitization are discussed in this paper. Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the graphitized material, which was found to resemble highly oriented graphite at certain laser fluencies. The proposed approach to the problem of perfect local diamond graphitization is an important step toward creating all-carbon composite systems consisting of conductive and dielectric phases. [ABSTRACT FROM AUTHOR]

The precipitation mechanism of the Q phase in Al-Mg-Si-Cu alloys has long been the subject of ambiguity and debate since its metastable phase (Q′) has the same crystal structure and similar lattice parameters as its equilibrium counterparts. In the present work, the evolution of the Q′ (Q) phase during aging is studied by combination of quantitative atomic-resolution scanning transmission electron microscopy and atom probe tomography. It was found that the transformation from the Q′ to the Q phase involves changes of the occupancy of Al atoms in atomic columns of the Q′ (Q) phase. The Al atoms incorporated in the Cu, Si and Mg columns are gradually released into the Al matrix, while mixing between Cu and Si atoms occurs in the Si columns. This transformation process is mainly attributed to the low lattice misfit of the equilibrium Q phase. Besides, the formation of various compositions of the Q phase is due to the different occupancy in the atomic columns of the Q phase. The occupancy changes in the columns of the Q phase are kinetically controlled and are strongly influenced by the alloy composition and aging temperature. [ABSTRACT FROM AUTHOR]

A new method for synthesis of 2D nanocrystals in water was proposed. The use of perfluorothiophenolate ions as surfactant allowed us to produce 2D single-crystal nanosheets of CaS at pH=9 and flat nanocrystals of PbS at pH=9 at room temperature. Mesocrystalline nanobelts of CdS and mesocrystals of PbS were obtained at pH=3–5 and pH=10–12, respectively. Morphology, structure and chemical composition of nanoparticles were characterized by high-resolution transmission electron microscopy, electron diffraction and energy dispersive X-ray spectroscopy. A mechanism of nanoparticles formation was discussed. [ABSTRACT FROM AUTHOR]

This paper reports the analysis of the intensity of diamond line in the Raman spectra of laser modified layers with different thickness on a diamond surface. Since the diamond line passing from substrate through the absorbing layer of moderate thickness can be registered, the thickness of local area is estimated from its micro‐Raman spectra. The comparison between Raman scattering and direct observation of the graphitized layer by transmission electron microscopy shows that Raman spectroscopy can be used as an alternative non‐destructive method for measuring a moderate thickness of graphitized layers. [ABSTRACT FROM AUTHOR]

Diamond platelets of sub-micrometer size were obtained by chemical vapor deposition technique from CH 4 /H 2 gas mixture activated by a direct current discharge. Comprehensive characterization of the diamond platelets was performed with use of scanning and transmission electron microscopy. The diamond platelet crystallites were found to be in the deposited material in form of stacked or isolated hexagonal platelets in combination with polyhedron crystallites. Six-fold rotational symmetry and composition of stacked (111) atom planes in the diamond platelets was revealed from analysis of the electron diffraction patterns. The structure and possible growth mechanisms of the platelets in the case of direct current plasma-enhanced chemical vapor deposition are discussed. [ABSTRACT FROM AUTHOR]

Phase formation and transitions in platinum silicide films on polycrystalline Si in the process of Pt magnetron sputtering and heat treatments at different temperatures are studied using X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and X-ray diffractometry. Phases of amorphous and polycrystalline Pt 3 Si and Pt 2 Si are shown to form during the room-temperature Pt deposition on poly-Si beneath the Pt layer. The relaxation of the interfacial film and partial transformation of Pt 3 Si into Pt 2 Si occurs as a result of the thermal treatment for 30 min in the temperature range from 125°C to 300°С. The Pt 3 Si and Pt 2 Si phases crystallize to PtSi due to annealing at the temperatures from 320°C to 480°С for the same time period. Image 1 • Interface domain in magnetron sputtered and annealed Pt/poly-Si film is studied. • Pt 3 Si and Pt 2 Si phases form at room temperature during Pt deposition on poly-Si. • Interfacial film relaxation turns Pt 3 Si to Pt 2 Si due to annealing at 100 < T < 200 °C. • Pt 3 Si and Pt 2 Si transit to PtSi due to annealing at temperatures from 320 to 480 °C. • Pt 3 Si phase is detected up to the annealing temperature of 350 °C. [ABSTRACT FROM AUTHOR]