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The Relation between Chemical Bonding and Ultrafast Crystal Growth
Author(s) -
Lee Tae Hoon,
Elliott Stephen R.
Publication year - 2017
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201700814
Subject(s) - lone pair , materials science , supercooling , chemical physics , amorphous solid , chemical bond , electron localization function , covalent bond , phase (matter) , crystallography , charge (physics) , nanotechnology , electron , molecule , thermodynamics , chemistry , physics , organic chemistry , quantum mechanics
Glasses are often described as supercooled liquids, whose structures are topologically disordered like a liquid, but nevertheless retain short‐range structural order. Structural complexity is often associated with complicated electron‐charge distributions in glassy systems, making a detailed investigation challenging even for short‐range structural order, let alone their atomic dynamics. This is particularly problematic for lone‐pair‐rich, semiconducting materials, such as phase‐change materials (PCMs). Here, this study shows that analytical methods for studying bonding, based on the electron‐charge density, rather than a conventional atomic pair‐correlation‐function approach, allows an in‐depth investigation into the chemical‐bonding network, as well as lone pairs, of the prototypical PCM, Ge 2 Sb 2 Te 5 (GST). It is demonstrated that the structurally flexible building units of the amorphous GST network, intimately linked to the presence of distinctly coexisting weak covalent and lone‐pair interactions, give rise to cooperative structural‐ordering processes, by which ultrafast crystal growth becomes possible. This finding may universally apply to other PCMs.