Defect-induced amorphization

Although most of the amorphous materials modelled by MD have been prepared by melting either a crystalline or random structure and quenching the resulting melt to generate the appropriate glassy structure, other methods of preparation have also been used such as pressure induced amorphization, defect induced amorphization, and radiation induced amorphization. Examples will be considered below. 

This approach, however, requires the absence of ill-defined carbon deposits originating from defect-induced soot formation on the surface of nanocarbons during their synthesis. Pyrolytic structures often counteract the control over activity and selectivity in catalytic applications of well-defined nanocarbons by offering an abundance of highly reactive sites, however, in maximum structural diversity. Although some nanocarbons are equipped with a superior oxidation stability over disordered carbons [25], such amorphous structures can further induce the combustion of the well-ordered sp2 domains by creating local hotspots. Thermal or mild oxidative treatment,... 

The effects of damage by ion implantation on the low-temperature diffusion of dopant can also be studied by implanting Si+ or Ge+ ions into predeposited layers in Si. Recently, Servidori et al. (58) studied the influence of lattice defects induced by Si+ implantation. Using triple crystal X-ray diffraction and TEM, they confirmed (1) that below the original amorphous surface-crystal interface, interstitial dislocation loops and interstitial clusters exist and (2) that epitaxial regrowth leaves a vacancy-rich region in the surface. 

Fecht, H.J. Defect-induced melting and solid-state amorphization. Nature 1992, 356, 133-135. 

Barone. M. E.. and Maroudas. D., Defect-induced amorphization of crystalline silicon as a mechanism of disordered-region formation during ion implantation. J. Comp.-Aid. Mater. Des. 4. 63-73 (1997). 

Massobrio et al. (1989, 1990) studied defect-induced amorphization in NiZr2 using a constant number of particles, constant pressure and constant temperature (NPT) MD and tight-binding potentials, by randomly exchanging a number of Ni and Zr atoms. They observed a volume increase in the system. The change in volume is more pronounced as the degree of chemical disorder introduced increases. The amorphous structure is similar to a structure obtained from a quenched liquid. 

Based on the preceding results, we can say that linearly polarized light from the band-gap absorption region can induce either transitory changes or crystallization transformation in amorphous Sbj Sei alloys. These two phenomena critically depend on exposure, show threshold behavior, and seem to arise from apparently different mechanisms defect states or some kind of structural units given preferential orientation under the action of linearly polarized light. 

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