Facilitation of Nucleation of Polymorphic Solids due to the Presence of Multiple Metastable Phases: Effects of Nonclassical Surface Tension

Banerjee, Puja and Bagchi, Biman (2019) Facilitation of Nucleation of Polymorphic Solids due to the Presence of Multiple Metastable Phases: Effects of Nonclassical Surface Tension. In: JOURNAL OF PHYSICAL CHEMISTRY C, 123 (34, SI). pp. 21207-21212.

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Abstract

Surface tension plays an integral part in our discussions on the formation of new phases from melt, although a quantitative understanding of the surface tension is almost completely lacking, especially in the synthesis of polymorphic solids. This lacuna can be appreciated if we realize that even a semiquantitative understanding of the celebrated Ostwald's step rule does not exist. A dramatic lowering of the surface energy of a growing nucleus happens when the stable phase grows from melt in the presence of several amorphous metastable phases. The later phases have characteristics intermediate between the initial and final phases. This reduction in surface tension may dictate the rate of both nucleation and growth in a manner hitherto unexplored. In this work, an order parameter-based approach is developed and applied to quantify the effects of such metastable phases. Interestingly, the total surface energy between melt and stable solid phases displays a fractional dependence on the number of metastable phases (N-MS). At higher temperature, this effect is observed to be much stronger. This fractional dependence of surface energy is related to the curvature of free-energy surface (that varies with temperature, pressure, etc.), assumed plausible ordering of metastable phases in the interface, and has consequence in nanomaterial synthesis.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY C
Publisher:	AMER CHEMICAL SOC
Additional Information:	copyright for this article belongs to AMER CHEMICAL SOC
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	18 Oct 2019 10:01
Last Modified:	18 Oct 2019 10:01
URI:	http://eprints.iisc.ac.in/id/eprint/63693

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