Aggregates grown from molten films

Crystals and Aggregates Grown from Molten Films, 94... 

CRYSTALS AND AGGREGATES GROWN FROM MOLTEN FILMS... 

Far more common are studies of two-dimensional spherulites typically grown in films of thickness d < 10 pm to avoid multiple aggregates being superimposed on one another in the thickness direction. When viewed from above in an optical microscope, such polycrystalline structures are circular in outline and have full rotational symmetry about the disk axis before impingement (see Fig. 3.4). Other microscopies and microdiffraction can be brought to bear to elucidate the fine-scale structure within the spherulite. With only minor qualifications, two-dimensional spherulites are equivalent to diametral sections of three-dimensional spherulites [76]. The adjective two-dimensional is technically incorrect, as mature spherulites such as those in Figure 3.5 have a disk thickness of about 5-10 pm (the assumed thickness of the molten film). Nevertheless, growth is two-dimensional after the spherulite diameter exceeds the film thickness. 

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