Revealing thermally-activated nucleation pathways of diffusionless solid-to-solid transition

Abstract

Solid-to-solid transitions usually occur via athermal nucleation pathways on pre-existing defects due to immense strain energy. However, the extent to which athermal nucleation persists under low strain energy comparable to the interface energy, and whether thermally-activated nucleation is still possible are mostly unknown. To address these questions, the microscopic observation of the transformation dynamics is a prerequisite. Using a charged colloidal system that allows the triggering of an fcc-to-bcc transition while enabling in-situ single-particle-level observation, we experimentally find both athermal and thermally-activated pathways controlled by the softness of the parent crystal. In particular, we reveal three new transition pathways: ingrain homogeneous nucleation driven by spontaneous dislocation generation, heterogeneous nucleation assisted by premelting grain boundaries, and wall-assisted growth. Our findings reveal the physical principles behind the system-dependent pathway selection and shed light on the control of solid-to-solid transitions through the parent phase’s softness and defect landscape.

Enabling Reversible Reaction by Uniform Distribution of Heterogeneous Intermediates on Defect‐Rich SnSSe/C Layered Heterostructure for Ultralong‐Cycling Sodium Storage

“…It is confirmed that the defects within the crystal texture serve as the primary source of nucleation sites and tend to induce the homogeneous growth of atomic clusters, in terms of quantum‐dot‐level uniform distribution of heterogeneous intermediates. [ 38,40,41 ]…”

“…It is confirmed that the defects within the crystal texture serve as the primary source of nucleation sites and tend to induce the homogeneous growth of atomic clusters, in terms of quantum-dot-level uniform distribution of heterogeneous intermediates. [38,40,41] After that, the following diffraction peaks emerged at 19.1, 33.0, and 34.8° below 0.7 V are indexed to the multi-step alloy reaction products of K 9 Sn 4 (200), K 23 Sn 4 (220), and K 23 Sn 4 (510), respectively. [42] During the charging process, the reverse phase transformation is clearly observed by the disappearance of Na 2 S/Na 2 Se intermediates.…”

An overview into advantages and applications of conventional and unconventional hydro(solvo)thermal approaches for novel advanced materials design

“…In the last few decades, an enormous library of nanocrystals has been designed using the colloidal approach, which is essentially a phase separation process primarily associated with nucleation and crystal growth stages [116,[153][154][155][156][157][158][159][160][161]207]. In general, it is well known that colloidal systems are distorted solid structures primarily responsible for the nucleation step [208,209]. From this perspective, nucleation as a solute precursor occurs in systems that present their suspended solid phase with a high degree of dispersion, which contributes to the growth stage of nanoparticles [58,[210][211][212][213].…”

Multistep nucleation visualized during solid-state crystallization

“…4 Nucleation, the first and most critical step in crystallization, is commonly described by classical nucleation theory (CNT) in the past century, which states that nascent nuclei are directly assembled from atomic or molecular ions in supersaturated environments via a single-step pathway by overcoming a free energy barrier. 5,6 Despite CNT's success in describing a range of crystal nucleation scenarios, 7–10 considerable crystallization phenomena have been suggested to show qualitative and quantitative deviations from CNT; 11,12 e.g. even for single-component nonpolar fluids, there is a few orders of magnitude difference between the CNT predicted and measured nucleation rates.…”