Bizarre Properties of Glass Allow Creation of "Metallic Glass" 265
VindictivePantz writes to mention that scientists have discovered some bizarre properties of glass and are already applying that knowledge to create what is being called "metallic glass." "The breakthrough involved solving the decades-old problem of just what glass is. It has been known that that despite its solid appearance, glass and gels are actually in a 'jammed' state of matter — somewhere between liquid and solid — that moves very slowly. Like cars in a traffic jam, atoms in a glass are in something like suspended animation, unable to reach their destination because the route is blocked by their neighbors. So even though glass is a hard substance, it never quite becomes a proper solid, according to chemists and materials scientists."
Get the terminology straight ... (Score:5, Informative)
Scotty... (Score:5, Informative)
Perpetuating old myths (Score:5, Informative)
This is crap. [wikipedia.org] There have been windows of old buildings "sagging" upwards. The old technology of making windowpanes resulted in glass of uneven thickness, and it makes sense to install it the thick side down. Sometimes the installers did not care enough.
misleading (Score:3, Informative)
Re:Perpetuating old myths (Score:5, Informative)
For larger sheets, you put the thicker (stronger) end of the glass sheet at the bottom, because the bottom of the sheet has to carry the weight.
Re:Don't we already know this? (Score:5, Informative)
Glass does not "flow". Perhaps you've read such articles, and they are assuredly all bullshit.
Materials scientists call glass an amorphous solid.
Re:Don't we already know this? (Score:5, Informative)
It's widely known and widely taught, but it's not so. Glass does not flow at any measurable rate at room temperature. Glass at room temperature is an amorphous solid, not a liquid.
Re:Don't we already know this? (Score:2, Informative)
http://en.wikipedia.org/wiki/Glass#Behavior_of_antique_glass [wikipedia.org]
Re:Don't we already know this? (Score:5, Informative)
Except, as noted above, that's not true at all [wikipedia.org]. You learned it in high school because you had a bad science teacher, and shame on "livescience.com" for perpetuating such nonsense. Glass is an amorphous solid, not a 'slow liquid.' It shares one or two characteristics with supercooled liquids [wikipedia.org], but it is different in several important ways.
terrible summary of not great science (Score:5, Informative)
Second of all, I don't really like the experiment that these people conducted. They simulated atoms during solidification, but they used microspheres within ANOTHER medium. With glasses, during there is no matrix material within which other molecules are moving. I find their model and extrapolation to be questionable. We are still trying to thermodynamically understand the glass transition and the solid amorphous state compared to the solid crystalline state.
Re:Perpetuating old myths (Score:5, Informative)
And not only that, the nonsense about glass not being solid because it isn't crystalline is another oft repeated chestnut that is incorrect. There are plenty of non-crystalline solids, like wood, bone, cement, and pink and white iced animal cookies. Also pancakes. A soft solid, yes, but solid nonetheless.
You could even make a case that silicon in its pure, glassy state is already a form of "metallic glass". It certainly looks like it.
Re:Perpetuating old myths (Score:5, Informative)
There is another distortion effect that myth attributes to liquid flow of glass... if you observe old architectural glass, you may note "waviness" in the glass. This is cause by how sheet glass was made.
A leader is dipped into molten glass, then raised slowly. While the glass is pretty much of uniform thickness, there is distortion caused by variations in temperature as the sheet cools.
If you're looking at old houses, it's interesting to note what kind of distortion is present in the windows -- this can tell you how the glass was made, which in turn can tell you if it's likely that the glass is original to the house. One needs knowledge of the history of window fabrication, which is often regional... but I digress.
This is yet another example of something making sense, but not being accurate. Yes, glass is technically liquid. But, the flow rate is such that the effects we attribute to the liquidity of glass would take millions and millions of years to occur at STP. Typically any effects in glass that are due to liquid flow occurred during the hardening stage.
Transparent Aluminum... (Score:4, Informative)
Transparent Aluminum isn't fiction and never was.
Al(2)O(3) is sapphire. Personally I wear a watch made of Titanium and Sapphire.
Re:Perpetuating old myths (Score:0, Informative)
Maybe you should A) Read the article you quote and B) be a bit more skeptical of the WEAKipedia, which often contradicts itself. From the article you just quoted:
Some glasses have a glass transition temperature close to or below room temperature. The behaviour of a material that has a glass transition close to room temperature depends upon the timescale during which the material is manipulated. If the material is hit it may break like a solid glass, however if the material is left on a table for a week it may flow like a liquid.
TFA is sensationalistic (Score:5, Informative)
Aside from repeating the old myth that glass can actually sag over hundreds of years, the article says very little. Perhaps a bad summary.
The jist of linked the story is:
A group of scientists in Bristol, Canberra and Tokyo used a material (doesn't say what) analogous to glass, not glass. This material is easier to study. Using this material they claim they were able to understand better what happens on the atomic level as it solidifies, and why it never really becomes a crystal. Nowhere in the article does it explain why this will lead to "metallic glass"
Here [nature.com] is an abstract for the original article. Pretty complex wording, but nothing about metallic glass.
Re:Perpetuating old myths (Score:2, Informative)
As a further nit-pick, I'd note that icosahedrons are not made from pentagons. I think they mean dodecahedrons, the faces of which are pentagons:
Re:Perpetuating old myths (Score:5, Informative)
The article is full of meaningless or incorrect statements. Like: As a researcher in the field, I can assure you that this isn't a controversial statement. We all agree that glasses are not at equilibrium. We all agree that the low-energy state for glasses is to crystallize, and that (in principle), if you wait long enough they will crystallize. The questions revolve around details like "how far from equilibrium?", "what are the implications of being non-equilibrium (e.g. on phase transitions)?", "what are the kinetics and dynamics?", "how long would it ~actually~ take for a given amount of change/flow/reconstruction/etc.?"...
Also, equating "equilibrium" with "being a solid" is total nonsense. (Solids, liquids, and gases can all be at equilibrium or far from equilibrium...)
In short, don't waste your time with this ridiculously hyped review of some otherwise interesting (but not revolutionary) science.
Re:Perpetuating old myths (Score:3, Informative)
Glass does not sag, at least not on a historical scale. Maybe to a geologist it sags.
Re:Don't we already know this? (Score:5, Informative)
Re:Transparent Aluminum... (Score:5, Informative)
Please, no.
Single crystals of alumina (Al2O3) are transparent. They are known as sapphire if clear or blue. With slight chromium impurities, they are known as ruby. They are a ceramic, not a metal. There are three oxygen atoms for every two aluminum atoms, which makes it 60%at oxygen. It is not aluminum. It would make more sense to say your watch is made of oxygen, but not by much.
Just saying "aluminum" implies the metallic structure, which will never be transparent despite the fervent hopes of many a Star Trek fan. The inherent availability of free electrons in the conduction band of metallic aluminum will ensure that is will not be transparent in any thickness greater than a few hundred nanometers. Truly transparent, metallic aluminum would be a breakthrough on par with a working transporter.
IAAPhDMS (I Am A PhD in Materials Science), and this has been your Pedantic Slashdot Rant from a Expert(TM) for today.
Back on topic. These metallic glasses (Vitraloy and the like) have been around for a decade now and have very interesting properties. They are not, however, transparent. Not even a little bit.
Icosahedron has triangular faces (Score:2, Informative)
From TFA:
An icosahedron has triangular faces. You were thinking of a dodecahedron, perhaps, which has pentagonal faces? The icosahedron's only relation to anything pentagonal (that I'm aware of) is that its dual polyhedron happens to be a dodecahedron.
Re:Tiger Woods would live this. (Score:1, Informative)
The only reason it can is because all metal drivers have to conform to a specific standard set by the Golfing industry in order to be qualified for use in tournaments.
He probably made it without regards to this standard, so obviously yes it probably did hit it farther.
Glass is not "technically" liquid. (Score:5, Informative)
Glass is not a liquid of any kind, "technically" or otherwise.
Glass is a solid.
Glass is not a crystalline solid.
Glass is an amorphous solid.
Yes, I am a materials engineer.
Re:Transparent Aluminum! (Score:3, Informative)
Re:LIQUID ALUMINUM??????? (Score:5, Informative)
I thought this was an urban legend:
"The deceptively liquid-like behavior of glass can be seen when you look at glass in the windows of an old building. The glass begins to sag and distort internally over the centuries, due to the effect of gravity."
This was because old glass making techniques used a spinning wheel to flatten and cool the glass so that one edge was slightly thicker when it was cut into the desired pieces. The whole sagging myth was made up. A common citation for rebuffing the myth is egyption glass that has held its form for much longer than the old english buildings.
Re:terrible summary of not great science (Score:5, Informative)
Oy gevalt (Score:1, Informative)
Unmitigated crap. I hope to god that this was due to the journalist liberally spicing the thing up with his/her own misconceptions. Glass is not a liquid, it does not flow measurably over any reasonable time period, and metallic glass has been around a while. Furthermore, metallic glass does have ceramic properties. Metals are largely useful due to weldability, machinability, ductility, and malleability. Mettalic glass does not generally share these properties. The article is written terribly - "particles called colloids"? Come on, how did this get on slashdot?
Re:LIQUID ALUMINUM??????? (Score:2, Informative)
Metallic Glass Not Equal to Transparent Aluminum (Score:5, Informative)
Glass is Silcon based,
Transparent Aluminum is Aluminum based, it is also known as the gemstone White Sapphire and looks much like diamonds. In fact it has been used for diamond like effects, but doesn't have the brilliance of diamonds (due to different reflective indexes).
Glass MOHS: ~ 5.5
Transparent Aluminun: MOHS = 9. Much harder, better crystaline structure, denser.
And as far as the article's claims, all solids move, but glass definitely is an abnormal material.
Re:LIQUID ALUMINUM??????? (Score:5, Informative)
they also placed the glass with the thicker area on the bottom because it was heavier, and it's a better idea to put the heavier part of the glass nearer the bottom of the frame. This led to practically all of those panes being installed thicker-side-down. So I suppose you could say gravity was responsible for the pane thickness variance... indirectly.
Re:LIQUID ALUMINUM??????? (Score:1, Informative)
Because the invention came from a plexiglass company in San Francisco in the 80's.
Re:New band names. (Score:5, Informative)
I know these posts are not serous, but the term metallic glass does not refer to transparent metals, but rather metals with an amorphus structure. Metallic glass lacks the fracture points associated with the crystal lattice of metals. This means that metallic glass does not fagigue over time as normal metals would. I believe that metallic glasses were first discovered by rapidally cooling laminants of titanium (I think I read somewhere that a WW2 nazi scientist fisrt discovered them).
Re:Perpetuating old myths (Score:5, Informative)
I can't believe this stuff still gets repeated.
It gets repeated because this particular tidbit of misinformation happened to make it into a very popular undergrad chemistry textbook:
College Chemistry with Qualitative Analysis, Sixth Edition, Nebergall, Holtzclaw, Robinson. p743, section 27.12
It didn't take much of a stretch, no pun intended, for the explanation of thickening of the bottom of cathedral windows to include this little tidbit.
This is far from new (Score:1, Informative)
Re:Aluminium glass (Score:5, Informative)
or this? [wikipedia.org]
Re:Perpetuating old myths (Score:3, Informative)
Re:LIQUID ALUMINUM??????? (Score:3, Informative)
If it is metallic then it can't be transparent. You know "sea of electrons" stuff. Electromagnetic fields wont penetrate it due to the skin depth [wikipedia.org] of metallic solids. Unless the conduction is anisotropic, then it would be much more interesting that "transparent aluminium".
Re:Gel (Score:3, Informative)
If you discount the medium gel could be considered a, -for lack of a better term- jammed precipitate. The whole point of TFA was that gel can be used to model the particle-interaction that takes place in glass because both can't settle into a more stable state.
Re:misleading (Score:2, Informative)