Researchers have discovered structural regularity hidden in silica glass. Image: Motoki Shiga.Glass – whether used to insulate our homes or as the screen in our computers and smartphones – is a fundamental material. Yet, despite its long usage throughout human history, the disordered structure of its atomic configuration still baffles scientists, making understanding and controlling its structural nature challenging. This disordered structure also makes it difficult to design efficient functional materials made from glass.
To uncover more about the structural regularity hidden in glassy materials, a research group has focused on ring shapes in the chemically bonded networks of glass. This group, including Motoki Shiga from Tohoku University's Unprecedented-scale Data Analytics Center in Japan, created new criteria for quantifying the rings' three-dimensional structure and structural symmetries, which they termed ‘roundness’ and ‘roughness’.
Using these indicators, the group was able to determine the exact number of representative ring shapes in crystalline and glassy silica (SiO2), finding a mixture of rings unique to glass and rings that resembled those in the crystal. Additionally, the researchers developed a technique for measuring the spatial atomic densities around the rings by determining the direction of each ring.
This revealed that there is anisotropy around each ring – i.e. the regulation of the atomic configuration is not uniform in all directions – and that the structural ordering related to this ring-originated anisotropy is consistent with experimental evidence, like the diffraction data from SiO2. It also revealed that there were specific areas where the atomic arrangement followed some degree of order or regularity, even though the arrangement of atoms in glassy silica appeared to be a discorded and chaotic.
"The structural unit and structural order beyond the chemical bond had long been assumed through experimental observations but its identification has eluded scientists until now," says Shiga. "Furthermore, our successful analysis contributes to understanding phase-transitions, such as vitrification and crystallization of materials, and provides the mathematical descriptions necessary for controlling material structures and material properties." The group reports its findings in a paper in Communications Materials.
Looking ahead, Shiga and his colleagues will use these techniques to come up with procedures for exploring glass materials, based on data-driven approaches like machine learning and artificial intelligence.
This story is adapted from material from Tohoku University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.