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Transparent Aluminum Is Here
Alien54 writes "Scientists in the US have developed a novel technique to make bulk quantities of glass from alumina for the first time. (link includes a picture of samples) Anatoly Rosenflanz and colleagues at 3M in Minnesota used a "flame-spray" technique to alloy alumina (aluminium oxide) with rare-earth metal oxides to produce strong glass with good optical properties. The method avoids many of the problems encountered in conventional glass forming and could, say the team, be extended to other oxides (see also: A Rosenflanz et al. 2004 Nature 430 761). Scotty would be pleased."
Yes. It seems that he didn't pollute the time-line after all.
A programmer is a machine for converting coffee into code.
The whales will have a safe journey home!
Now I can watch as the food in the fridge turns green... Ye-hah!
Glass breakthrough
11 August 2004
Scientists in the US have developed a novel technique to make bulk quantities of glass from alumina for the first time. Anatoly Rosenflanz and colleagues at 3M in Minnesota used a "flame-spray" technique to alloy alumina (aluminium oxide) with rare-earth metal oxides to produce strong glass with good optical properties. The method avoids many of the problems encountered in conventional glass forming and could, say the team, be extended to other oxides (A Rosenflanz et al. 2004 Nature 430 761).
Glass is formed when a molten material is cooled so quickly that its constituent atoms do not have time to align themselves into an ordered lattice. However, it is difficult to make glasses from most materials because they need to be cooled -- or quenched -- at rates of up to 10 million degrees per second.
Silica is widely used in glass-making because the quenching rates are much lower, but researchers would like to make glass from alumina as well because of its superior mechanical and optical properties. Alumina can form glass if it is alloyed with calcium or rare-earth oxides, but the required quenching rate can be as high as 1000 degrees per second, which makes it difficult to produce bulk quantities.
Rosenflanz and colleagues started by mixing around 80 mole % of powdered alumina with various rare-earth oxide powders -- including lanthanum, gadolinium and yttrium oxides. Next, they fed the powders into a high-temperature hydrogen-oxygen flame to produce molten particles that were then quenched in water. The resulting glass beads, which were less than 140 microns across, were then heat-treated -- or sintered -- at around 1000C. This produced bulk glass samples in which nanocrystalline alumina-rich phases were dispersed throughout a glassy matrix. The new method avoids the need to apply pressures of 1 gigapascal or more, as is required in existing techniques.
Click to enlarge
Aluminate glasses
The 3M scientists characterised the glasses using optical microscopy, scanning electron microscopy, X-ray diffraction and thermal analysis, and tested the strength of the materials with hardness and fracture toughness tests. They found that their samples were much harder than conventional silica-based glasses and were almost as hard as pure polycrystalline alumina.
Moreover, over 95% of the glasses were transparent (see figure) and had attractive optical properties. For example, fully crystallized alumina-rare earth oxide ceramics showed high refractive indices if the grains were kept below a certain size.
Author
Belle Dumé is Science Writer at PhysicsWeb
who doesn't know the difference between Alumina and Aluminum.
What next, suggesting people use the silicon in their computers as a breast implant?
Athletic Scholarships to universities make as much sense as academic scholarships to sports teams.
Aren't many jewels aluminum compounds?t s/13.html
google search of rubies and aluminum:
http://pearl1.lanl.gov/periodic/elemen
One of the great things about sci-fi as a thematic backdrop (be it literature or movies/tv) is that it alone of all the genres has the possibility of inspiring a tangible effect upon the real world.
I remember an interview with James Doohan where he said his greatest pride that came from his career was that he inspired other people to pursue careers where they could make a difference to the world. How many engineers became engineers or went into sciences because of Star Trek?
I'm familiar with the Arthur C Clarke suggesting satellites; I doubt a similar cause/effect with Star Trek IV happened here. However, the similarities are cool, and at least with this genre there is the POSSIBILITY of changing the world for the better.
PS Fortunately such transitions from sci-fi fantasy to real world are few and far between. 90%+ of tv SF and pulp SF is dreck, and I myself and not looking forward to a Brave New World...
John Maynard Keynes: "When the facts change, I change my mind. What do you do?"
A common misconception caused by the old "spun" method of making glass which makes sheets which are thicker at the bottom than the top. People have often assumed that old glass has "flowed" into that shape. It hasn't: it was made that way. Glass does not in fact flow, not even slowly.
Search on Google for "glass flow" for lots and lots of stuff about this.
TWW
"Encyclopedia" is to "Wikipedia" what "Library" is to "Some people at a bus stop"
There is some debate, the scientific consensus at the moment is that (ordinary) glass is NOT a liquid. Wikipedia has some interesting background info on this discussion.
In general, the composition of glass makes a huge different in properties such as hardness, inertness, transparancy and color. In ordinary glass, CaO is added to lower solubility in water and various other solvents.
"Attractive optical properties" must be nerd talk for "pretty"...
Seems a couple other people beat me to rebuking this, but I figured I'd throw another link in just in case there is any lingering doubt.
Glass is not a liquid. Glass is an amorphous solid.
All editorial writers ever do is come down from the hill after the battle is over and shoot the wounded.
"actually, communicators are more like radio communication ... you don't dial any number ..."
Why more like radio?
My email is smart enough that if I start typing the first 2 or 3 letters of an email, it can guess at who I want to send it to and be accurate most of the time. I don't need to know the email addresses of anyone involved these days unless I don't have them in my address book which is sync'd between my phone, 2 PCs and 3 Macs. All work about the same.
So you don't dial a number, but you do say "Sulu, Can We Get A Fix On..." and the internal processing realizes that since he didn't refer to a specific Sulu, he must mean the default one and routes it appropriately.
My Cell is smart enough that if I hold a button on the side and say the name it can dial about a dozen numbers. Battery life and processing speeds preclude it from listening all the time.
So, are you saying that because our technology isn't very sufficient today, theirs too must be as unadvanced. I've seen attainable advancements in 10 years that make 20 years ago look like the stone ages. In another 10 years, maybe we will just speak into a phone, and it will wait until it figures out who we are talking too and route accordingly. Who knows. Maybe we will all be back to fighting wars with sticks and stones.
Transparent Aluminum Is Here
NO IT ISN'T! Commercially developed transparent Alumina (think clear ruby/sapphire) is here, HUGE difference. Sorry Trek fans, you will have to wait longer. There will be no clear planes, no clear cases made of Alumina. If cases were transparent Alumina then they would have the same properties as silica glass and you would have a nice greenhouse effect going on slowly (or not so slowly) frying your computer.
Alumina is a mineral/glass/ceramic, Aluminum is a metal!
Somehow, I get the feeling that Apple is going to use this for the next gen of PowerBooks.
(It's a joke -- all the materials scientists don't need to correct me.)
-"Zow"
As If a million Startrek geeks cryed out in joy.
You have 5 Moderator Points!
Which Helpless Linux zealot/MS basher do you want to mod down today?
Sure it's been said but bears repeating.
If you have a high quality watch it is likely that the crystal is made from polycrystalline alumina (i.e. corundum...in this case synthetic corundum). The alumina glass is different however in the fact that it is a glass and therefore lacks crystal structure.
Since it doesn't have to be crystallized it is likely that it will be able to be produced in large sizes. However, being a glass it is not going to have the malleable properties of aluminum metal and will probably shatter if hit hard enough.
Sort of....
A better way of explaining it would be that for a photon to be absorbed by an electron, there must be an empty higher energy state for the electron to move to (E = Eo + hv, where Eo is the energy state of the electron and hv is the energy of the photon). In solids with metallic bonding, there are many electrons floating around and many free electronic states for them to move to, so any photon that enters the solid can be absorbed by an electron that will then jump to a higher energy state (which will be free, because there are so many free energy states).
In the case of insulating and semiconducting materials, there is a gap in the energy states, so some transitions are not allowed. For pure, single crystal Al2O3, (aka white sapphire), there are (essentially) no transitions available that correspond to the energy of photons of visible light. If you start substituting in Cr3+ ions for the Al3+ ions, your sapphire will turn red and we call it "ruby". In this case, the Cr impurities provide transitions that can absorb wide ranges of visible light, but not red light. What is more is (if this is fairly pure), the ruby will not only absorb light of other wavelengths, but it will emit red light as well. Try putting a synthetic ruby under a UV light, it will glow red.
However, it should be noted that other defects can scatter and absorb light as well. Grain boundaries, voids, inclusions, etc. will affect your light transmittance. It has been possible for some time now to make polycrystalline alumina that is translucent (Lucalox), but polycrystalline alumina can never be transparant, so there are two ways to make alumina transparant: make it single crystal (only one grain, so no grain boundaries) or amorphous (no grain boundaries, because there is no long range crystal order).
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The internet is the greatest source of biased information in the history of mankind.
I once knew a guy who had this great idea to use aluminum oxide on DVDs and CDs to prevent scratching. He said the disks could be bulletproof, scratchproof, and unbreakable, although I think he was exagerating...
If that was the case, that would be an AWESOME application for this. Although the MP/RIAA would see that as a reason for preventing backup copies of your media. I mean, if the disk can't be damaged, why would you need a backup? Although you could still lose it or have it stolen...
...spike
Ewwwwww, coconut...
"Rosenflanz and colleagues at 3M in Minnesota" One of those colleagues wouldn't happen to be named Guildenstein, would they?
This news should not be surprising to anyone, since it's essentially a dupe! http://science.slashdot.org/article.pl?sid=02/02/2 0/0358206&tid=126&tid=14 [slashdot.org]
The amusing thing, is that American scientists are given credit here, but if you look at the original article from 2+1/2 years ago, it was the Germans who discovered it. Hmmm...
You could argue that this article is just a 'refinement' of the previous article. I could believe that only if a link had been provided to the original article. Ah well... Odd that the article itself doesn't mention previous work by the Germans either...
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Come on, what kind of geek are you?
"The amount of intelligence on this planet is a constant. The population is growing." -Cole's Axiom