Revealing the Cluster‐Cloud and Its Role in Nanocrystallization. Issue 16 (7th March 2019)

• Record Type: Journal Article
• Authors: Jin, Biao; Wang, Yanming; Liu, Zhaoming; France‐Lanord, Arthur; Grossman, Jeffrey C.; Jin, Chuanhong; Tang, Ruikang
• Is Part Of: Advanced materials. Volume 31:Issue 16(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-03-07
• Subjects: cluster‐cloud -- crystallization -- LC‐TEM -- nanoparticle -- out‐and‐in relaxation; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201808225
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Elucidating the early stages of crystallization from supersaturated solutions is of critical importance, but remains a great challenge. An in situ liquid cell transmission electron microscopy study reveals an intermediate state of condensed atomic clusters during Pd and Au crystallizations, which is named a "cluster‐cloud." It is found that nucleation is initiated by the collapse of a cluster‐cloud, first forming a nanoparticle. The subsequent particle maturation proceeds via multiple out‐and‐in relaxations of the cluster‐cloud to improve crystallinity: from a poorly crystallized phase, the particle evolves into a well‐defined single‐crystal phase. Both experimental investigations and atomistic simulations suggest that the cluster‐cloud‐mediated nanocrystallization involves an order–disorder phase separation and reconstruction, which is energetically favored compared to local rearrangements within the particle. This finding grants new insights into nanocrystallization mechanisms, and provides useful information for the improvement of synthesis pathways of nanocrystals. Abstract : Liquid cell transmission electron microscopy reveals a new nanocrystallization pathway. The nanoparticle crystallization is mediated by an important intermediate phase of condensed atomic cluster aggregates, which is defined as a cluster‐cloud. Specifically, it follows three fundamental steps: formation of the cluster‐cloud through the aggregation of clusters; condensation of the cluster‐cloud to a poorly crystallized nanoparticle; and multiple out‐and‐in relaxations toward a single crystal via order–disorder phase separation.