Structure and stresses in a system of two mechanical twins in titanium

In the work we have presented the results of experimental studies and mathematical modeling for the processes of the structure formation in a transition zone of wedge-type twins system in commercially pure titanium. The process of interaction of structure defects with twinning dislocations during the formation of a wedge-type twin was taken into consideration. It is shown that the interaction alters the stress maximum in vicinity of boundaries in the system two wedge-type twi

Segregation of platinum on the (110) surface of palladium

Platinum segregation on a high-purity Pd(110) surface has been investigated by low-energy ion scattering spectrometry. As a result of a combined surface cleaning by ion etching and by a "burst", a perfect single crystalline structure free of O, H, N, and C impurities has been revealed, in spite of these impurities being present in the initial specimens. The temperature dependence of segregation of Pt on the Pd(110) surface has been studied

On a peculiarity of low-energy ion scattering from a well-ordered bcc W(2 1 1) surface

A peculiarity in the backscattering of keV He+ ions by a well-ordered high-purity W(2 1 1) surface is reported. Besides the normal elastic binary collision peak and the low-energy tail due to backscattering in deeper layers, an extra peak is observed for an inelastic loss of about 95 eV. This unusually large loss has a constant value over a wide range of primary energies (1.5-4.5 keV). An extra peculiarity is that the peak is only observed for the scattering in normal incidence towards the (2 1 1) plane. It is also not seen for polycrystalline W. The energy loss may be due to a quasi-double or -triple collisions of He particles with the row-trough structure of W(2 1 1) involving electronic excitation of both He and W atoms. Alternatively it may be due to a special channeling/dechanneling process for the incident ions

Fabrication of [001]-Oriented Tungsten Tips for High Resolution Scanning Tunneling Microscopy

The structure of the [001]-oriented single crystalline tungsten probes sharpened in ultra-high vacuum using electron beam heating and ion sputtering has been studied using scanning and transmission electron microscopy. The electron microscopy data prove reproducible fabrication of the single-apex tips with nanoscale pyramids grained by the {011} planes at the apexes. These sharp, [001]-oriented tungsten tips have been successfully utilized in high resolution scanning tunneling microscopy imaging of HOPG(0001), SiC(001) and graphene/SiC(001) surfaces. The electron microscopy characterization performed before and after the high resolution STM experiments provides direct correlation between the tip structure and picoscale spatial resolution achieved in the experiments

Electron-beam growing and purification of W crystals

High-purity W single crystals have been grown by the electron-beam floating zone melting technique. The structural quality of these crystals was subsequently improved by the application of a strain-annealing technique. X-ray diffraction methods revealed a near-perfect crystallographic structure. Well-ordered clean W surfaces free from all contaminants were obtained by a two-step heating procedure. Low-energy ion scattering and Auger electron spectroscopy confirmed that the cleaning procedures removed all impurities and that the crystal faces expose only W in the outermost atomic layers. Thin layers of Re were deposited on a W(110) single crystal by magnetron sputtering and investigated by ion scattering and Auger electron spectroscopy