Kazuto Arakawa

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The activation energy for the long-range intrinsic migration of selfinterstitial atoms (SIAs) in metals, EI m, is an important physical quantity closely associated with microstructural evolution upon energetic particle irradiation. The EI m values for various metals have been widely investigated through recovery experiments on specimens irradiated at low(More)
The dynamic behaviour of atomic-size disarrangements of atoms-point defects (self-interstitial atoms (SIAs) and vacancies)-often governs the macroscopic properties of crystalline materials. However, the dynamics of SIAs have not been fully uncovered because of their rapid migration. Using a combination of high-voltage transmission electron microscopy and(More)
By using the perpendicular-exchange-biased Pt/Co/α-Cr(2)O(3) system, we provide experimental evidence that the unreversed uncompensated Cr spins exist at the Co/α-Cr(2)O(3) interface. The unreversed uncompensated Cr spin manifests itself in both the vertical shift of an element-specific magnetization curve and the relative peak intensity of soft-x-ray(More)
We quantitatively analyzed the contrast degradation and blur of 20-nm gold nanoparticles adsorbed on the top of amorphous silicon films of thicknesses of 0.54, 1.09, 1.63 and 2.2 μm in bright-field transmission electron microscope (TEM) images taken at accelerating voltages of 0.5, 1, 2 and 3 MeV. The thickness dependence of the transmission was well(More)
Vacancy-mediated climb models cannot account for the fast, direct coalescence of dislocation loops seen experimentally. An alternative mechanism, self climb, allows prismatic dislocation loops to move away from their glide surface via pipe diffusion around the loop perimeter, independent of any vacancy atmosphere. Despite the known importance of self climb,(More)
We propose new techniques of electron irradiation for studying the kinetics of simple point defects and their agglomeration, by making the most use of the intrinsic function of an ultrahigh-voltage scanning transmission electron microscope. The methods enable us to realize a very high defect production rate at a localized area and create a spot or(More)
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