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The valence and coordination structure of implanted Cu and Br ions were investigated by x-ray absorption fine structure spectroscopy in (2.4 MeV 6 × 1016 Br2+ ions cm−2+ 2 MeV 6 × 1016 Cu+ ions cm−2)-implanted silica glass. It was found that the implanted Cu and Br atoms were coordinated by oxygen atoms and silicon atoms, respectively, in as-implanted glass. After heating at 600 °C, at least two-thirds of the Cu atoms were coordinated by Br atoms without the formation of crystals. The γCuBr crystal was formed after heating to 1100 °C. It was deduced that the coordination structure of Cu and Br atoms depends on defects as well as thermochemical stability and mass transport processes.
Structure of Cu ions in (Cl+Cu)-, (Br+Cu)-, (I+Cu)-, (S+Cu)- and (Se+Cu)-ion implanted silica glasses has been studied by x-ray absorption and optical absorption spectroscopies. Cu ions formed Cu-O bonds in the as-implanted glasses, due to the homogeneous distribution of Cu ions and the low local concentration of halogen and chalcogen ions in silica glass. Heat treatment at about 600°C caused the formation of bonds between Cu ions and halogen/chalcogen ions without forming Cu halide or chalcogenide crystals. It was deduced that the formation of these bonds was controlled by the diffusion of Cu ions in silica glass. On the other hands, it was inferred that the formation of Cu halide and chalcogenide crystals was controlled not only by the diffusion of halogen/chalcogen ions but also by the diffusion of matrix ions.
Coordination structures of implanted Fe, Co, and Ni ions were studied in 1.78–2.00-MeV 5 × 1016 ions/cm2-implanted silica glasses by x-ray absorption and optical absorption spectroscopies. It was found from x-ray absorption spectra that the implanted Fe, Co, and Ni ions are coordinated by ca.3 oxygen atoms. The implanted ions dispersed in glass matrix and did not form crystals. The valence of the implanted ions was about 1.5. The Fe–O, Co–O, and Ni–O interatomic distances were 190, 191, and 192 pm, respectively. In addition, it was found from optical absorption spectra that one-fifth of implanted Co ions were present as Co2+ ions in tetrahedral symmetry.
Coordination state of gold atoms implanted in silica glass to an energy of 1.5 MeV and a dose of 1 × 1017 ions/cm2 has been studied by x-ray absorption fine structure spectroscopy. It was found that most of the gold atoms form gold clusters in which the nearest neighboring Au–Au interatomic distance is shorter by 0.05 °A than that in bulk gold. The contraction of Au–Au interatomic distance of gold clusters in silica glass is less than that reported in the previous studies on gold clusters within the other substrates. Gold atoms are coordinated by about four gold atoms in average. In addition, it was found that Au–O bonds are formed at the gold clusters/silica glass interface. It was deduced that the formation of Au–O bond at the gold clusters/silica glass interface depresses the contraction of Au–Au interatomic distance.
The structure of ultrafine gold particles embedded in silica glass by ion implantation has been studied by x-ray absorption fine structure spectroscopy. It is found that the Au–Au interatomic distance in the particles is very similar to that in bulk gold within 0.01 Å. Mean-square relative displacement in the particles is 1.2–1.3 times larger than that in bulk gold.
Hydrogen implanted into ceramic YBa2Cu3O7−x (YBCO) with a dose of 1 × 1017 H+ cm−2 started to effuse as molecular hydrogen from the YBCO to atmosphere at a temperature of 200 °C, effuse predominantly as water by reacting with oxygen at temperatures of 300–700 °C, and again effuse as molecular hydrogen at temperatures above 800 °C. The improvement of the superconducting properties of the proton implanted YBCO occurred at annealing temperatures for which implanted hydrogen effused predominantly as water by reacting with oxygen.
Focused Ar-ion laser and MeV ion beams were impinged onto stainless-steel foils to investigate the localized modification of the magnetic property associated with the phase transformation. The magnetic signal intensity of the Ar-ion laser irradiated areas was found to locally decrease at a laser power of 350 mW and almost extinguish at 550 mW with a beam spot size of 13.2 μm (at 1/e intensity) because of the localized retransformation into austenite. On the other hand, the magnetic signal intensity was found to increase by 3 MeV Au+ implantation because of the localized martensitic transformation. The magnetic signal for ferromagnetic substrates was much more enhanced than that for non-magnetic substrates. These results indicate that the beam-induced localized phase-transformation in stainless-steel can be applied to fixed magnetic recording.
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