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Disappearing polymorph - Wikipedia

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In materials science, a disappearing polymorph is a form of a crystal structure that is suddenly unable to be produced, instead transforming into a different crystal structure with the same chemical composition (a polymorph) during nucleation.[2][3] Sometimes the resulting transformation is extremely hard or impractical to reverse, because the new polymorph may be more stable.[4] It is hypothesized that contact with a single microscopic seed crystal of the new polymorph can be enough to start a chain reaction causing the transformation of a much larger mass of material.[5] Widespread contamination with such microscopic seed crystals may lead to the impression that the original polymorph has "disappeared". In a few cases such as progesterone and paroxetine hydrochloride, the disappearance is global, and it is suspected that it is because earth's atmosphere is permeated with tiny seed crystals. It is believed that seeds as small as a few million molecules (about 10 − 15 grams) is suffi

Disappearing polymorph - Wikipedia Jump to content From Wikipedia, the free encyclopedia Phenomenon in materials science Needles of two different polymorphs of metanilic acid taken under a microscope at 20× magnification. Figure (a) shows Form II and (b) shows Form III; Form I was unable to be reproduced by researchers, an instance of a disappearing polymorph. [ 1 ] In materials science , a disappearing polymorph is a form of a crystal structure (a morph ) that is suddenly unable to be produced, instead transforming into a different crystal structure with the same chemical composition (a polym

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