Crystalline-amorphous interface boundaries

Generally, three to four lifetime components are resolved in polymers, and their attribution is as follows. The shortest lifetime component ri with intensity h is attributed to contributions from free positron annihilation (inclusive of p-Ps lifetime). The intermediate lifetime component Z2 with intensity 12 is considered to be due to the annihilation of positrons trapped at defects present in the crystalline regions, or those trapped at the crystalline-amorphous interface boundaries. The longest-lived component T3 with intensity 1, is due to pick-off annihilation of the o-Ps in the free volume cavities present mainly in the amorphous regions of the polymer [42,43]. The simple model of a Ps atom in a spherical potential well of radius R leads to a correlation between o-Ps hfetime and R [70,128-130] ... 

There are different criterion of how to classify solid-solid interfaces. One is the sharpness of the boundary. It could be abrupt on an atomic scale as, for example, in III-IV semiconductor heterostructures prepared by molecular beam epitaxy. In contrast, interdiffusion can create broad transitions. Surface reactions can lead to the formation of a thin layer of a new compound. The interfacial structure and composition will therefore depend on temperature, diffusion coefficient, miscibility, and reactivity of the components. Another criterion is the crystallinity of the interface. The interface may be crystalline-crystalline, crystalline-amorphous, or completely amorphous. Even when both solids are crystalline, the interface may be disturbed and exhibit a high density of defects. 

Based on conceptions of work [105] the specific dielectric relaxation in PPX with M nanoparticles is supposed to be connected with reorientation of dipoles in polymer environment of M nanoparticles that accompanies the electron transfer between M nanoparticles of percolation cluster. Dipole centers in PPX are (Tv-units of polymer chains on a surface of lamellar PPX crystallites. Such centers are characteristic, in particular, for extended polymer defects (dislocations, grain boundaries, interfaces between amorphous and crystalline areas) where, most probably, M nanoparticles are formed. 

D less than 4 suggest that the boundary is not smooth, due to some degree of interpenetration between the amorphous and crystalline phases at the interface. 

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