Growth and form of spherulites

Abstract

Many structural materials (metal alloys, polymers, minerals, etc.) are formed by quenching liquids into crystalline solids. This highly non-equilibrium process often leads to polycrystalline growth patterns that are broadly termed 'spherulites' because of their large-scale average spherical shape. Despite the prevalence and practical importance of spherulite formation, only rather qualitative concepts of this phenomenon exist. The present work explains the growth and form of these fundamental condensed matter structures on the basis of a unified field theoretic approach. Our phase field model is the first to incorporate the essential ingredients for this type crystal growth: anisotropies in both the surface energy and interface mobilities that are responsible for needle-like growth, trapping of local orientational order due to either static heterogeneities (impurities) or dynamic heterogeneities in highly supercooled liquids, and a preferred relative grain orientation induced by a misorientation-dependent grain boundary energy. Our calculations indicate that the diversity of spherulite growth forms arises from a competition between the ordering effect of discrete local crystallographic symmetries and the randomization of the local crystallographic orientation that accompanies crystal grain nucleation at the growth front (growth front nucleation or GFN). The large-scale isotropy of spherulitic growth arises from the predominance of GFN.

Estimation of polymer nucleation and growth rates by overall DSC crystallization rates

“…In fact, besides polymers, several substances form spherulites. 22 Moreover, three-dimensional spherulites can be observed by crystallizing polymers from a solution. 23 In the case of three-dimensional spherulites, it is only necessary to consider the volume…”

Rate-Dependent Morphology of Li2O2 Growth in Li–O2 Batteries

“…After the initial phase of Li 2 O 2 particle nucleation analyzed here, the particle morphology evolves from disc-like to toroid-like under certain conditions [53], that may be describable by our approach, e.g. by including electron transport and elastic strain.…”

Spherulitic Growth of Coral Skeletons and Synthetic Aragonite: Nature’s Three-Dimensional Printing

“…2,6,7 Received: January 6, 2017 Accepted: May 31, 2017 Published: May 31, 2017 Space-filling is the second key characteristic of spherulites, which distinguishes them from other crystals formed by dendritic or fractal growth. 7,13 To fill space a spherulite must contain crystals oriented in all possible directions, neighboring crystals must be slightly mis-oriented by NCB, therefore the two key characteristics are related to one another.…”

“…2,6,7 Coral skeletons are among the most important biominerals because they form coral reefs, the most biodiverse ecosystems in the ocean. These have received increased attention in recent decades because they are threatened by global warming and ocean acidification.…”