Characterizing Crystalline-Vitreous Structures: From Atomically Resolved Silica to Macroscopic Bubble Rafts

Abstract

A two-part experiment using bubble rafts to analyze amorphous structures is presented. In the first part, the distinctions between crystalline and vitreous structures are examined. In the second part, the interface between crystalline and amorphous regions is considered. Bubble rafts are easy to produce and provide excellent analogy to recent research results on the atomic structure of silica glass. Ring statistics are employed to characterize the 2D structures and results from student bubble raft data are compared to results from atomically resolved images of amorphous 2D silica; the bubble rafts demonstrate good qualitative agreement. In these experiments, students learn how to characterize crystalline and amorphous materials and are introduced to current research results and analysis techniques for amorphous material structures

Growth and Atomic‐Scale Characterization of Ultrathin Silica and Germania Films: The Crucial Role of the Metal Support

“…2gives as ar esult 3, which is close to fulfilling the equation. [129] This subtle discrepancy is explained partially by the edge effect and by the non-perfectly regular polygons that constitute the film.…”

Assessing the amorphousness and periodicity of common domain boundaries in silica bilayers on Ru(0 0 0 1)

“…A sum which deviates from zero indicates a deformation of the flat 2D structure. Amorphous 2D silica comparably fulfills the requirement of Euler's theorem [45]. The ring neighborhoods introduced in 57 domain boundaries can be compared with those present in the amorphous phase.…”

“…Whether these phases represent distinct systems or a continuous transition of the same system with domain boundaries comprising an ever larger percentage of the film structure can be assessed by considering spatial distributions of rings across a crystalline-amorphous interface in comparison with domain boundary structures. Studies of the ring statistics across a lateral transition between crystalline and amorphous regions of the bilayer silica have shown that this transition is continuous [36,45]. In moving from crystalline to amorphous regimes, five-and seven-membered rings are introduced first while four-, eight-, and nine-membered rings appear later in the transition.…”

Crystalline thin films of silica: modelling, structure and energetics

“…Recently developed synthetic pathways have allowed thin films of SiO 2 to be deposited on either metallic [7][8][9][10][11][12][13][14][15][16] or graphitic [17] substrates, whilst advances in imaging techniques now allow for true atomic resolution of the surface structure. Some of the thinnest films deposited are interpreted as having structures based on bilayers of corner-sharing SiO 4 CP in which all of the Si and O atoms obtain their full (four-and two-respectively) coordination numbers.…”