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Thermal annealing-induced recrystallisation in Fe ion-implanted Si was investigated by transmission electron microscopy. Single crystals of Si(111) were implanted with 120 keV Fe ions to a fluence of 1.0×1017 cm-2 at cryogenic temperature. A buried amorphous Fe-Si layer in an amorphous Si matrix was formed in the as-implanted sample. Nanobeam electron diffraction revealed that metastable α-FeSi2 precipitates embedded in the amorphous Si matrix were formed after annealing at 350 °C for 8 h. The formation of this α-FeSi2-derived phase was unusual, because it has been observed only in epitaxially grown thin films. Based on the Fe1-xSi (02 in the amorphous matrix. [ABSTRACT FROM AUTHOR]

We have synthesized iron silicides on a Si(111) substrate using an electron-beam evaporation technique in combination with thermal annealing. The microstructures, as a function of heating rate on annealing, were characterized by transmission electron microscopy (TEM). Bright-field plan-view TEM observations revealed that a discontinuous thin film is formed in the sample annealed rapidly, while complete separated nanoparticles were obtained in the specimen annealed slowly. Selected-area and nano-beam electron diffraction patterns indicated that the former and latter specimens mainly consist of iron monosilicide ( ɛ-FeSi) and iron disilicide ( β-FeSi2) phases, respectively. [ABSTRACT FROM AUTHOR]

Atomistic structures of as-deposited and laser-induced-crystallized Ge-Sb-Sn layers have been examined using high-resolution electron microscopy (HREM) and nanobeam electron diffraction (NBED). Cross-sectional observations were performed on Ge-Sb-Sn thin films embedded in a multi-layered structure. Crystalline clusters were frequently observed in the HREM images of the as-deposited amorphous Ge-Sb-Sn thin film. Autocorrelation function analysis of the HREM image indicated a similarity between the structures of the crystalline clusters and that of rhombohedral Sb. Atomic pair-distribution functions obtained from the halo NBED intensity of the as-deposited amorphous Ge-Sb-Sn films also showed development of local structure whose atomic configuration is similar to that of the rhombohedral Sb. NBED revealed that the structure of the crystallized Ge-Sb-Sn thin film is also close to that of rhombohedral Sb. The atomistic structures of Ge-Sb-Sn thin films were compared with those of Ge-Sb-Te thin films and the rapid crystallization mechanism of these materials was discussed. [ABSTRACT FROM AUTHOR]

This paper describes the results obtained in respect of typical human errors together with their information-processing phases, causal factors and situational factors found commonly among incidents analysed at domestic nuclear power plants (NPPs). The Central Research Institute of Electric Power Industry has been conducting detailed and structured analysis of all incidents reported during the last 31 years and has stored them in a database. At first, all case studies were classified into several categories. Next, multivariate analysis was applied. These results suggested that there were several occurrence patterns that were identified how errors occurred at NPPs in the past. [ABSTRACT FROM AUTHOR]

Structural changes taking place during the tempering proceed in four stages. At the preliminary stage taking place below 370 K, interstitial carbon atom clusters are formed below 270 K, rearrange to make a modulated structure between 270 and 360 K, and disappear at about 370 K. A long period ordered phase with respect to the interstitial carbon atoM or interstitial vacancies also appears between 330 and 350 K. With the disappearance of these structures, the first stage takes place between 370 and 470 K, where η-FeC is formed in the matrix of low carbon martensite. The second stage o°Curs around 550 K with the retained austenite decomposing to θ-FeC and α iron. At the su°Cession of the first stage, the third stage appears in a temperature range from 470 to 900 K, where θ-FeC, X-FeC and also higher carbides θ-FeC intergrow microsyntactically in the particles precipitated below 720 K, but only θ-FeC is formed above this temperature. [ABSTRACT FROM AUTHOR]

The ground state energy of nano particles of the CuAu alloy is calculated by utilizing the modified embedded atom method(MEAM), and a computer simulation is made of the order-disorder transition therein by Monte Carlo method with the many-body potential obtained by MEAM. The calculations have been made for three kinds of model crystals of nano particles with 2 nm and 3 nm in diameter, containing 321 and 1061 atoms, respectively, and of a bulk with a size of 5 × 5 × 5 unit cells, on which the periodic boundary condition is imposed. As a result, it is found that the difference in ground state energy between perfectly ordered and disordered states becomes less in nano particles than in the bulk, and that the critical temperature T decreases markedly with decreasing particle size. According to our previous experiments, there seems to be a certain critical size for the atomic ordering in the nano particles, and T is depressed remarkably in the nano particles. These experimental results appear to be accounted for by the present calculated ones qualitatively. [ABSTRACT FROM AUTHOR]