High electric field induced formation of novel ions such as H+3, AuH+2, RhHe2+, and PtHe2+2 on metal surfaces has been studied in the pulsed-laser time-of-flight atom-probe field ion microscope. From the fractional abundances, and the high resolution mass spectra and energy distributions measured for these ions, several conclusions can be drawn. Field desorption of hydrogen below the evaporation field of the substrate often results in formation of H+3 ions. This formation depends not only on the applied field strength, but surprisingly also on the material and the atomic structure of the substrate. Plenty of H+3 ions can be found from the high index planes and the lattice steps of Mo, W, and Au surfaces in the field range of 2 to 3 V/Å. Few are found from Ir and Ni surfaces, and none are found from the densely packed W(110) plane. Formation of H+3 can therefore be considered a surface catalyzed and field induced chemical reaction. Using H2–D2 mixed gases, we find little correlation between the ionic species obseved in field desorption and the chemisorption states of the gases. The field desorbed ions are formed directly from the field adsorbed state. Field adsorption occurs mostly in the diatomic molecular form. On highly protruded atomic sites of some materials, field adsorption occurs also partly in the triatomic molecular form. Field evaporation of metals in hydrogen or helium often results in the formation of metal hydride and metal helide ions. These ions are formed right at the metal surface by a polarization binding. A fraction of them dissociates in the high field region near the surface. The ‘‘dissociation zone’’ is found to be only several Å in width. From this width, the average lifetime of these complex ions in a field of 3 to 4.4 V/Å is estimated to be on the order of 5×10−13 s.
Oxidated Ti (primarily rutile TiO2 ) was produced using a facile and rapid O-PIII treatment procedure, which enhances the biocompatibility of the Ti surface with potential implications for further dental implant application.
O-PIII treatment could enhance the corrosion resistance and cell adhesion of Ti surface for dental implant application due to the increase in surface thickness of Ti-oxides (mainly as TiO(2)) on Ti.
Indentation forces, including constant rate and oscillating mode, were applied to SiO(2)/Si and diamond-like carbon (DLC)/Si specimens. A two-stage behavior was exhibited in the force-depth results after delamination occurred. When the depth was smaller than the threshold value, a linear load-depth relationship was exhibited because the debonded film was suspended over the substrate. Membrane theory was applied to analyze the deflection of the suspended film, and thus the in-plane stress exhibited in the debonded film was evaluated. Through the proposed method, the strain energy release rate of the interface can be directly evaluated by analyzing the force-depth data of the indentation tests.
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