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

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.