Glass Breakthrough May Lead to New Sustainable Materials
by Tim McGee, Helena, MT, USA on 06.22.08
Photo by Duke LeNoir via flickr
Glass is a Molecular Traffic Jam
Is glass a liquid or a solid? An article published today in Nature Materials provides evidence that glass is actually more like a 'traffic jam'. It turns out the atoms in a glassy solid would 'like' to form a crystalline solid, or regular structure, but just aren't able to get organized enough. Instead the atoms loosely organize themselves into groups or relationships shaped like an icosahedron.
If you tried to stack many of these icosahedral shapes together in 3 dimensions you would not be able to form a solid surface where all the sides touch, a requirement for a crystalline solid. Yet, because they do form some shape, they get stuck in a 'traffic jam', so it is not a liquid either. This geometry gives glass unique materials properties.
Understanding this little bit of glass geometry may have a big impact on the type of glassy materials we can create. "For a long time, no-one has really shown what the structure of glass is," says Patrick Royall from the University of Bristol, UK, "but we have been able to show how the structure of a glass differs from that of a liquid."
Glass in Technology
Glass has been an important material throughout human history, from obsidian blades to optical fibers and sex toys. But, we are not the only species who uses glass. Scientists have shown that plants and animals can 'grow' glass at room temperature and pressure, like the sea sponges that have glass skeletons.
Understanding the physics of glass is a big step in developing our ability to produce materials in a more sustainable fashion. Royall argues that this basic understanding opens up new doors for creating a range metallic glasses that would be more resilient to structural failure, and potentially useful in a number of modern applications. You may see metallic glass wings on an airplane, or novel glass materials in the structure of a fuel efficient car in the not too distant future.
via: New Scientist
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A typically unsatisfying Treehugger post.
Transparent aluminum, here we come!
Transparent aluminum already exists. Or more specifically, transparent alumina, which is made of aluminum oxide. It was invented about a decade ago.
The sustainability of a material depends on how it is obtained and how it is recycled, not what it is made of. This article shows a breakthrough in understanding how glass is structured, but this development doesn't really offer anything in the way of sustainability.
i wonder if transparent bamboo might be made this way!
Cool
So, wait. Would metalic glasses be stronger than regular metals, lighter than regular metals, or is it more like they'd serve as a stronger alternative to regular silicon glass? Would they be transparent? Would they shatter like glass rather than bend?
The "glass is a liquid" confusion stems from a basic misunderstanding of the definitions of liquid and solid.
The everyday definition of a liquid is "something that flows or has viscosity" Glass does not flow at human or even at geologic time scales; if it did, the 8000 year old obsidian points found in Alaska would not still be razor sharp. There are many incorrect examples that glass does flow, notably the common wisdom that cathedral glass is thicker on the bottom than on the top, but this is explained by the fact that it was common practice to hang glass with the heavy side down...
Glass as a liquid is a semantic argument. Physicists define a liquid as a substance that lacks "long range order" or crystallinity. Their argument does not include viscosity.
Tin, which none would argue is a liquid, has a lower viscosity than silica glass...
Amorphous metals have been known since the 1950s. This work merely points out that there is short range order (10s of angstroms) in some glasses.
Metallic glasses lack grains, and hence lack grain boundaries. They thus have interesting tribological (wear) corrosion and magnetic properties. More at wikipedia:
http://en.wikipedia.org/wiki/Metallic_glass
Not sure how this ties in with green / sustainability though.