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Transparent Aluminum

The news that there might be a way to make transparent aluminum — foretold, kindof, in Star Trek IV: The Voyage Home– has been around awhile. I was reading an article about it just now in New Scientist, and saw this quote:

“The substance itself is light-years ahead of glass,” said 1st Lt. Joseph La Monica, who heads the research.

I’m sure Lt. Monica is a smart man and a great engineer (as good as Scotty?), but he needs to read my website more.

Tip o’ the BA hat to Larry Kellogg for the link.

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December 30th, 2005 10:10 PM by Phil Plait in Astronomy, Debunking, Piece of mind, Science | 42 comments | RSS feed | Trackback >

42 Responses to “Transparent Aluminum”

  1. 1.   aiabx Says:
    December 30th, 2005 at 10:16 pm

    Was transparent aluminum foretold by Star Trek, or was it created, like flip-phones, because of Star Trek? If the latter, I have high hopes for FTL.
    -Andy B

  2. 2.   Wolverine Says:
    December 30th, 2005 at 10:42 pm

    I’d personally prefer this. Neat.

  3. 3.   KingNor Says:
    December 30th, 2005 at 11:02 pm

    this one time, i was only a few feet ahead of my time. that was a confusing day for me

  4. 4.   Jack Hagerty Says:
    December 31st, 2005 at 12:35 am

    Transparent aluminum has been used in industry for decades. We call it sapphire (AlO3). It is much more transparent than glass or quartz, in fact. It’s used for the viewports of plasma etching chambers because it is more transparent over a greater range of frequencies (from far IR to far UV) than any other common, well fairly common, material; plus etch products don’t stick to it.

    I’ve never understood how you can take an opaque metal, add some oxygen to it and have it turn completely clear. It’s also much cheaper than you’d expect. A 2.25″ (6 cm) diameter viewport costs about $275. That’s for a flawless, optically polished, single crystal sapphire weiging about half a pound (220 grams)!

    In non-crystalline form (actually microcrystalline form), AlO3 is used as ceramic, and also the protective coating on aluminum called “anodize.” It would seem that this new material is an offshoot of that with some nitrogen added.

    - Jack

  5. 5.   Thomas Siefert Says:
    December 31st, 2005 at 7:05 am

    aiabx, I don’t think that flip phones was created because of Star Trek, it’s just a design that makes good sense.
    In same ballpark though, I can’t help giggle every time I see a person with a blue-tooth phone headset. It’s just so.. eh.. so… Uhura.

  6. 6.   Archie Wayne Mangold II Says:
    December 31st, 2005 at 7:11 am

    Re: “he needs to read my site more.”

    It’s not uncommon for companies to describe themselves as “miles above the rest” or “miles ahead of the competition.” A simple goggle search reveals about 9,000 hits for the first phrase and 15,000 for the second. If miles, why not light years? It’s an exaggeration of more than five trillion, but I find no fault with the geammar.

    Curiously, the metric version (“kilometers above the rest”) seems much less common.

  7. 7.   Archie Wayne Mangold II Says:
    December 31st, 2005 at 7:14 am

    That’s “grammar,” not “geammar.” Sorry about that.

  8. 8.   Mark Martin Says:
    December 31st, 2005 at 7:17 am

    Jack, it’s funny you should mention sapphire as aluminum. Here’s some dialogue from “Moon Zero Two”:

    Whitsun
    “Too small to have either a name or a number, the asteroid was first photographed in 1998 when it happened to pass close to the earth. But it was never investigated or plotted.”

    Hubbard:
    “-Until two years ago.”

    Whitsun
    “This film was taken by Mr. Hubbard’s astronomical division. The asteroid is barely sixty feet by thirty by thirty. Estimated mass approximately six thousand tons.”

    Hubbard:
    “Do you read spectrograms Mr. Kempt?”

    Kempt:
    “Some of the easy ones. Looks… well it looks like Aluminum.”

    Hubbard:
    “Very good! It’s quite similar to aluminum, but an Aluminum that has been squeesed and roasted in the heart of an exploding planet hundreds of millions of years ago. What is the name again ?”

    Whitsun
    “A ceramic crystalline form of Corundum Aluminum Oxide.”

    Hubbard:
    “Yes. Sapphire, Mr. Kempt. Sapphire. Six thousand tons of the gemstone sapphire. That’s what’s so special about this asteroid.”

  9. 9.   Megan Says:
    December 31st, 2005 at 7:59 am

    Aluminum to me
    Aluminium to some
    You can shine like silver all you want
    But you’re just Aluminum….

    (From the songbook of BNL.)

  10. 10.   Richard Board Says:
    December 31st, 2005 at 8:00 am

    I agree with Archie Wayne Mangold II that the expression “light years ahead” of something or someone is not a grammatical error. I assume the user is suggesting a light year is a measure of distance, which it is – and not a measure of time. Imagine a marathon race in which the leading runner is 2 miles ahead of his nearest competitor. The metaphor is accurate when applied to being ahead of a business or social competitor as well.

    I know this is only semantics, but that’s the point. In colloquial conversation and correspondence, most people say many things that are not perfectly grammatically correct. Common errors are the misuse of data as a singular noun, or the comment that, “He is not as tall as me.”, instead of “He is not as tall as I (am).”

    What difference does it make in these constructions? As long as meaning is clear between the speaker/writer and his audience, accurate communication happens.

    And I still think that the use of “light years ahead” is a valid construction, when describing a lead over the competition or a comparison of where two or more things are in relation to each other. Isn’t that the definition of distance?

  11. 11.   collin nelson Says:
    December 31st, 2005 at 8:38 am

    this is pretycool. i would like to know how it holds up to intense heat. how far can this product be applied to future tecnologies?

  12. 12.   Nigel Depledge Says:
    December 31st, 2005 at 8:55 am

    Jack, thanks for the info on sapphire. I think that artificial sapphire is significantly cheaper than bits that have been dug out of the ground.

    When you say:
    “I’ve never understood how you can take an opaque metal, add some oxygen to it and have it turn completely clear,”

    The answer is reasonably strightforward. When aluminium and oxygen make chemical bonds, the way in which the electrons interact with photons of light changes. The consequence of this change is that it no longer absorbs the same wavelengths of light. A second effect that is also relevant is the way light is scattered. A particulate material or a material with a rough surface will scatter light (according to the size of the particles or the imperfections in its surface relative to the wavelength of the light). When the AlO3 is compressed into a single large crystal and polished, it no longer scatters as much light, so light can pass through it in straight paths.

    The two effects combine to make the material transparent.

    Quartz is also transparent when prepared in the right way (to UV and visible light), as is sodium chloride (transparent to IR and some visible).

  13. 13.   KingNor Says:
    December 31st, 2005 at 9:49 am

    generally people who say “light years ahead of its time” are trying to make the phrase “years ahead of its time” sound more scientific, or sci-fi.

    if he’d said “light years in front of the competition” then ok, but when i hear years and time in one sentance, i’m thinking clocks, not rulers.

    its like saying “i’m 20 feet ahead of 3:30″

    i vote for improper use of phrase.

  14. 14.   Tim G Says:
    December 31st, 2005 at 1:27 pm

    The phrase, “light-years ahead” doesn’t bother me that much. I put the phrase “miles ahead of the competition” into a search engine and got 15,700 web sites. “Years ahead of the competition” fared better, but not by magnitudes: 39,200 web sites.

    I’m fairly sure most people know that a light-year is a unit of distance.

  15. 15.   Tim G Says:
    December 31st, 2005 at 1:39 pm

    I wonder how this material compares to what is used on the space shuttle.

  16. 16.   Scott Moore Says:
    December 31st, 2005 at 1:51 pm

    “I wonder how this material compares to what is used on the space shuttle.”

    It’s light years as good!

  17. 17.   Marlayna Says:
    December 31st, 2005 at 2:17 pm

    LOL

    Tim, you’d be surprised how many people think a lightyear is a measure of time :( It’s a common misconception, and unfortunately I’ve seen it in literature as well as everyday life.

  18. 18.   Thomas Siefert Says:
    December 31st, 2005 at 2:48 pm

    A light-year is like a normal year, only with less calories.

  19. 19.   CR Says:
    January 1st, 2006 at 1:27 am

    Using a measure of distance as a measure of time… reminds me of a famous movie series. Hmm… maybe someone should use the term “parsecs ahead” instead. (It only takes 12 parsecs for Han Solo to make the Kessel Run!) :)

  20. 20.   marty light elliott Says:
    January 1st, 2006 at 2:27 am

    Happy New Lightyear
    Everybody

  21. 21.   Nigel Depledge Says:
    January 1st, 2006 at 7:21 am

    CR said:
    “Using a measure of distance as a measure of time… reminds me of a famous movie series. Hmm… maybe someone should use the term “parsecs ahead” instead. (It only takes 12 parsecs for Han Solo to make the Kessel Run!)”

    Or maybe he was referring to relativistic distance contraction, i.e. he travelled so fast that the distance contracted to less than 12 parsecs.

    No? Oh, well, never mind.

  22. 22.   Ick of the East Says:
    January 1st, 2006 at 8:09 am

    …..”A light-year is like a normal year, only with less calories.”

    Since we’re all being so pedantic, that should be “fewer” calories. (I read a book on grammar in only two parsecs.)

  23. 23.   James Buchanan (Doodler) Says:
    January 1st, 2006 at 8:22 am

    I read about this stuff a couple months ago when it was first announced they’d be using it in fighter jet canopy bubbles. Absolutely slick stuff. Though I guess it really did take’em years to figure out that matrix. :P

    As for the light year thing, I think its well established that its a bad application of the term, but if you see product development in terms of a race against competition, a distance based metaphor isn’t entirely out of line…so y’all stop floggin’ that poor dead horse or I’m calling PETA!! :)

  24. 24.   Thomas Siefert Says:
    January 1st, 2006 at 8:49 am

    On the Star Wars Episode IV DVD, George Lucas explains that the 12 parsec bummer was misunderstood by the audience. What Solo meant was that the navigation computer was so clever that it could find the shortest route for a FTL jump, i.e. the Kessel Run in 12 parsec, and thereby making the Millenium Falcon a fast ship.

    Yeah right George!

  25. 25.   Roy Batty Says:
    January 1st, 2006 at 10:23 am

    Lol.. yeah, Star Wars revisionist George as we affectionately know him as :-;

  26. 26.   SFwriter Says:
    January 1st, 2006 at 10:32 am

    And that’s Millennium, not Millenium… :-)

  27. 27.   Thomas Siefert Says:
    January 1st, 2006 at 12:56 pm

    SFwriter, Yeah I know about “millennium”, my spell checker has a YK problem.

  28. 28.   Ray Gray Says:
    January 1st, 2006 at 8:09 pm

    The capstone of the 555 foot Washington Monument is an aluminum pyramid. Now, take a dollar bill out of your wallet and look at The Great Seal of the United States of America that is printed on the reverse side.

    Looks to me like the pyramid (with the eye in it) is clear and transparent………there is nothing new under the Sun…. :*)

  29. 29.   Nigel Depledge Says:
    January 2nd, 2006 at 12:09 pm

    Ray, I have no dollar bills in my wallet – I live in the UK. I’ll take your word for it, though.

  30. 30.   Trevor Wood Says:
    January 2nd, 2006 at 4:26 pm

    Let’s keep the chemistry right here… alumina/aluminium oxide/sapphire/ruby is not aluminium, just as glass/silicon dioxide (mostly) is not metallic silicon. Both oxides are indeed transparent when pure. Synthetic ruby and sapphire are available from lapidary suppliers for around US$1.00 per gram…much cheaper than the dug ones!

  31. 31.   Jack Hagerty Says:
    January 2nd, 2006 at 4:36 pm

    Nigel -

    Thanks for the explanation. Now you know why I’m a mechanical engineer instead of a chemist :-)

  32. 32.   CR Says:
    January 2nd, 2006 at 11:39 pm

    Nigel said: “Or maybe he was referring to relativistic distance contraction, i.e. he travelled so fast that the distance contracted to less than 12 parsecs.
    No? Oh, well, never mind.”
    :)

  33. 33.   CR Says:
    January 2nd, 2006 at 11:43 pm

    Darn. That was supposed to be a :-) in response, not a :)

  34. 34.   CR Says:
    January 2nd, 2006 at 11:46 pm

    OK, something’s weird with the emoticons working at random… I’ll just mosey along now that I’ve wasted everyone’s time.

  35. 35.   Matt Opitz Says:
    January 3rd, 2006 at 7:22 am

    OK, I’m a materials engineer, specifically a ceramic engineer, and this whole “transparent aluminum” thing really irks me for some reason. Aluminum is a metal. Aluminum oxynitride is a ceramic. They are nothing at all alike or even “similar”. Saying that this armor material is transparent aluminum is like saying that rust, which is iron oxide, is merely “red steel”, or that the pigment they use for white paint (titanium dioxide) is actually “white titanium”. They’re completely different things! You will never have “transparent aluminum” because the metallic bonds in aluminum (and other metals) allow enough free electrons (well, free enough) in the structure to absorb any incoming photons due to resonance of the electrons with the incident electromagnetic fields. This is why metals are completely opaque. You CAN, however, have transparent ALUMINA (the common name for aluminum oxide, or sapphire) or aluminum oxynitride, which is what they talk about in the article. The ionic bonds in AlON not only don’t result in any free electrons that would resonate with the incoming light photons’ frequencies, but are also arranged such that they (the bonded ion pairs themselves) don’t resonate at those frequencies, either, making the material transparent at visible light frequencies for large single crystals of the materal or when the crystallite size is large enough for a polycrystalline version of the material (grain boundaries in polycrystalline ceramics act as scattering sites due to lattice mismatches at the boundaries).

    Oh and one more nitpicky thing, alumina is Al2O3, not AlO3…

  36. 36.   Irishman Says:
    January 3rd, 2006 at 3:22 pm

    Pssst, Phil, I think the guy’s name is Lt. La Monica.

  37. 37.   Irishman Says:
    January 3rd, 2006 at 3:26 pm

    Tim G Said:
    >I wonder how this material compares to what is used on the space shuttle.

    I imagine not very well. You’re thinking the durability and it being a ceramic, right? I think it’ probably still fairly heavy in comparison to shuttle tiles. About half the weight of glass for this new stuff? I’m not certain on the details, but glass is pretty heavy stuff, and shuttle tile material is interspersed with air to help with the weight and thermal mass issues.

  38. 38.   Wayne VanWeerthuizen Says:
    January 3rd, 2006 at 11:05 pm

    An loose analogy may help to explain how some substances are transparent. When the aluminum has its “hands” free, it can catch passing photons; but when it is holding on to adjacent oxygen atoms, it no longer has a free “hand” to catch the passing photon with.

    By “hand”, I rather mean available energy levels for its electrons. The molecule needs to have a particular energy level available to it in order to “catch” a particular frequency range of light. The formation of chemical bonds affects the energy levels that are available to each atom.

    Of course, reality is more complicated than this, but this should be enough to get the basic idea across. If you investigate it much deeper, you are likely to find yourself studying a subject called Quantum Electrodynamics, or QED.

  39. 39.   Matt Opitz Says:
    January 4th, 2006 at 9:43 am

    Space shuttle tiles (we had one we used for “show and tell” when I was at Penn State) are basically chunks of compressed glass foam. Now that doesn’t mean it’s “foamy” like soap, just that it’s more air than solid. The particulate part of the foam was very very fine, like chalk dust almost. We did a demonstration where one of us would stand with a space shuttle tile in our hand while another person blowtorched the opposite side for minutes at a time. You could feel the heat radiating from the top side of the tile and yet the bottom, where your hand was, would still be room temperature. Pretty cool stuff. But to answer the question, AlON armor is absolutely nothing at all like space shuttle tiles.

  40. 40.   JediBear Says:
    January 10th, 2006 at 4:55 am

    Pay attention to what the guy actually said.

    “The substance itself is light-years ahead of glass,”

    He’s not using light-years as a measure of distance or time but /technological progress/.

    There aren’t any units for that, or any firm measure for it, but in modernistic thought, we tend to think that technology gets better as time goes on — thus “years” might be an acceptable measure of progress — being a measure of time.

    What doesn’t fit is light-years. I can’t imagine any way to measure technological progress in terms of distance.

    There’s also the fact that what he said, with the word ‘light’ removed drops to the level of the fundamentally obvious — of /course/ it’s more advanced than glass. Glass has been in use for hundreds of years.

    A better sound bite might have been “This material is years ahead of even the most modern applications of glass.” Which would at least have left the poor guy sounding a little more educated.

    As an aside, I /have/ read a book in less than two hundred miles — I was on a car trip at the time.

  41. 41.   russell s Says:
    July 28th, 2006 at 12:42 am

    tranparent aluminium=Si6O12Al2
    i may not be a trekie
    but i made transparent aluminium in my lab
    it is strong and light waight…
    after it is heated …cool it with O2 gas
    to cause the SiO2 to bond in a crystal matricswith the Al..
    beware the cooling is some what expolsive.
    but the results are great.

  42. 42.   Ben Owen Says:
    April 16th, 2010 at 12:21 am

    Meanwhile, does it really say “sandwhiched” in that report? Livescience need to ease off the Cool-Whip…

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