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  (Source: Flawless Facets)
Sapphire would be three times as hard as Gorilla Glass

For centuries mankind has enjoyed brilliant blue sapphire gemstones.  Now scientists have learned to grow transparent sapphires and could soon use the lab-made stones to form smartphone screens.

Sapphire is the world's second hardest material, and is tougher than even the strongest Gorilla Glass.  Sapphire's crystalline structure is formed of a network of aluminum and oxygen atoms in a 2-to-3 ratio.

In a new report by the MIT Review, it is suggested that screens of the hard synthetic crystal could soon hit the market, improving the rigidity (drop resistance) and screen integrity (scratch resistance) of smartphones.  The report suggests that a sapphire screen would currently cost $30 USD/unit, versus $3 USD/unit for a Gorilla Glass screen.

That cost would make a sapphire screen to expensive for all but the most premium of flagship smartphones.  It's clear why Corning Inc.'s (GLW) Gorilla Glass has dominated sales to date, selling over 1 billion units.  However, given that sapphire is three times as hard as Gorilla Glass, the MIT Review report argues that some OEMs may feel compelled to make the switch.

Currently a few OEMs -- including Apple, Inc. (AAPL) use smaller sheets of sapphire glass as a cover to their smartphone camera lenses.

Eric Virey, an analyst for the French market research firm Yole Développement, said in an interview that the cost of sapphire screens could eventually drop to $20 USD/unit.  He comments, "I'm convinced that some (manufacturers) will start testing the water and release some high-end smartphones using sapphire in 2013."

Gorilla Glass
The current market leader is Corning's Gorilla Glass.

Corning spokesman Daniel Collins responded to the report, saying he is not convinced that sapphire units will be able to cannibalize the market for his company's product, nor compromise its growth.  He comments, "It is unclear to us if this could provide better overall performance than actual glass.  There also are the questions about cost and product weight that must be addressed before sapphire would be a serious consideration for mass market applications."

The latest Gorilla Glass, Gorilla Glass 3, is twice as hard as its predecessor (Gorilla Glass 2).

GT Advanced Tech
GT Advanced Tech aims to supplement smartphone glass, not necessarily replace it.  
[Image Source: GT Advanced Tech/ExtremeTech]

Ultimately the two technologies may coexist in some smartphones, though.  GT Advanced Technologies, Inc. (GTAT), a New Hampshire device startup, is aiming to produce a clear sapphire layer for smartphone and tablet that's as thick as a human hair (~0.1 mm), which would be added a strengthener/supplement to the currently used Gorilla Glass.  Synthetic glass and sapphire may soon be vying for market dominance, but ultimately they may do their best work as a team.

Sources: MIT Review, CNN [Corning Response]

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By futrtrubl on 3/21/2013 7:09:22 PM , Rating: 2
Now scientists have learned to grow transparent sapphires and could soon use the lab-made stones to form smartphone screens.

Synthetic clear sapphire has been around for a very long while now, mainly in watches. So while the ability to make large enough sheets for large phone screens may be new, the quoted sentence is incorrect.

RE: Incorrect
By chµck on 3/21/2013 8:30:25 PM , Rating: 2
yup, most discount jewelry has lab-created stones.

RE: Incorrect
By Souka on 3/22/2013 11:13:24 AM , Rating: 2
Sapphire is the world's second hardest material, and is tougher than even the strongest Gorilla Glass

So do we have actual numbers? or percentage improvement?

How does "tougher" and "hardest" equate to "rigidity (drop resistance) and screen integrity (scratch resistance)"

Only actual information I see is that the saphire screens will add at least $20 cost per phone... (cost to make the screen is not how much more the consumer will pay)

Anyhow... I want a saphire screen for my Acura's windshield... I keep getting rock chips and cracks in it, but none in my Prius! :)

My $.02

RE: Incorrect
By ati666 on 3/27/2013 10:20:35 AM , Rating: 2
dont tell that to your girlfriend

RE: Incorrect
By bhigh on 3/21/2013 8:40:37 PM , Rating: 2
Sheets of sapphire have been used in grocery store scanners for a while. I'm pretty sure they're at least as large as a phone's screen.

RE: Incorrect
By jimbojimbo on 3/22/2013 12:02:28 AM , Rating: 2
I think the main problem is making it thin enough to be viable for a cell phone and not diminish the touch capabilities.
My Omega watch has a sapphire face and I've had it for over 10 years now and accidentally smacked in on several brick walls but not a scratch. Love it.

RE: Incorrect
By ShieTar on 3/22/2013 3:58:52 AM , Rating: 2
I don't think so. I have been using 0.5mm thin sheets of synthetic single crystal sapphire in my PhD thesis, more than a decade ago. I think what really happened is just that somebody found a way to make the process cheaper.

Now if just somebody could do the same for synthetic diamond. 10.000$ per cm² is probably a bit much for a smartphone screen.

RE: Incorrect
By deksman2 on 3/22/2013 5:21:54 AM , Rating: 2
I agree with this assessment.
The technology is not new.
But, I would have preferred they used synthetic diamonds (which also can be produced in abundance since decades ago, and it was in the mid 90-ies it became practical for electronic chip use and overall usage in computers).

Technologies/materials like this are decades old actually.
The core difference is that the market takes time to find monetarily cheap ways of using them (which has nothing to do with our technological ability to create something in abundance with high energy/resource/technology efficiency, from the get go).
Market based economy is holding us back severely... and to top it off, many won't even use new technologies from the get go because its more profitable to 'milk' outdated technologies and make revisions for as long as they can.

That and the artificial notion of 'cost' is coming down at much faster pace the more automated our production is (which is nearly everything), so the rate of new materials/technologies trickling down to others even in the monetary system is accelerating (but the present socio-economic system is stupid/unsustainable since it creates large amounts of waste and doesn't recycle nearly anything - we had the ability to use all the landfills for material/tool/technology creation since the late 19th century, and there would be 0 need to extract new ones from the Earth since we knew back then to create synthetic materials with superior properties using less energy and raw material overall).

RE: Incorrect
By deksman2 on 3/22/2013 5:22:39 AM , Rating: 2
I would say this is a step in the right direction.

RE: Incorrect
By Solandri on 3/22/2013 6:18:44 AM , Rating: 5
1) They're also used as bulletproof glass panes in attack helicopters. And I guarantee you those are bigger than a smartphone screen.

2) Al2O3 is called corundum. To pick up the characteristic blue color of sapphires, it has to have certain impurities. Different impurities give it a red color, which we call rubies. But the pure, colorless variety is called corundum.

3) Corundum is more or less the natural state of aluminum (though usually not in crystalline form). Elemental aluminum is at a high energy state and reacts easily with oxygen, so is almost impossible to find in nature. The aluminum foil you have in your home is actually aluminum with a very thin layer of corundum surrounding it. The aluminum reacts with oxygen in the air to form this layer, which seals it off from the air and prevents further corrosion. (A similar thing happens with iron, except iron oxide, aka rust, doesn't seal the iron from the air, and so the rusting continues.)

4) Synthetic corundum crystals are relatively easy to make. You melt a bunch of Al2O3, put in a seed crystal, and let it slowly grow much like how silicon wafers are made. Synthetic diamonds are made much the same way, except you need pressures of about 50,000x atmospheric pressure before the crystals will form. That increases the cost tremendously and limits the size of the crystals you can grow. Mostly all you can make are industrial size diamonds (i.e. powder for coating drill bits and such). There's a vapor deposition method widely being researched, but with limited success.

RE: Incorrect
By othercents on 3/22/2013 8:29:24 AM , Rating: 2
Can you grow a whole phone out of it?

RE: Incorrect
By ShieTar on 3/22/2013 10:39:37 AM , Rating: 3
2) Technically correct, but synthetic corundum is almost exclusively sold as "sapphire" anyways.

4) There is a difference between poly-crystalline and mono-crystalline Al2O3, both in ease of production and in optical/mechanical properties. Poly-crystalline is much cheaper, but also breaks easier along the crystal barriers.

RE: Incorrect
By tng on 3/22/2013 8:24:31 AM , Rating: 3
make large enough sheets for large phone screens may be new
It is not new, but it is expensive. Sapphire wafers for semiconductor applications have been around for decades. These are mainly used in radiation hardened ICs used in many military uses, satellites, and oddly enough green/blue/white HI LEDs.

The problem is that a 150mm sapphire wafer at .7mm thick was $600 the last time I checked. That is an expensive screen.

RE: Incorrect
By 3DoubleD on 3/22/2013 10:11:13 AM , Rating: 3
Well non-semiconductor grade sapphire could be less expensive than semiconductor grade sapphire, the problem being that if you relaxed the "cleanliness" of your process to save money, you might end up with impurities causing the sapphire to turn blue or red. But so long as those specific impurities are eliminated, I'd expect that you could have relatively impure, clear sapphire at a reduced cost compared to semiconductor grade.

My major problem with this announcement is that while sapphire is the second hardest substance, that doesn't mean it isn't extremely brittle. Diamond may be the hardest material on earth, but even diamonds can break or chip readily if dropped the wrong way.

[If anyone reading this has worked with semiconductor sapphire substrates and could chime in as to how easy/difficult it was to cleave that would be appreciated]

Any single crystal material is prone to catastrophic failure by cleavage along certain crystal planes. One crack can propagate through the entire crystal. In materials like your average steel product, you have thousands of grains (crystals) between two surfaces. Each grain can be slightly or highly mis-oriented with respect to its neighbors, so a crack in one grain won't readily propagate across the entire material. Metals are also extremely ductile and the combination gives a material that does not shatter under normal conditions (but dents, scratches, and both readily elastically and plastically deforms without catastrophic failure).

In a single crystal, one crack will propagate through the entire material. There is nothing to stop it once enough force was delivered along a cleavage plane (and there are many possible cleavage planes). Gorilla Glass is just that, a glass. It's an amorphous matrix of their special blend of material. Amorphous materials can still crack, but crack propagation is SIGNIFICANTLY deterred due to the lack of crystalline order.

Sapphire also has a slightly higher refractive index than glass (including Gorilla Glass): ~1.7 vs ~1.5. This will lead to worse glare. I'm assuming they don't place any anti-reflective coatings over the sapphire or Gorilla Glass, since that would defeat most of the purpose of using such a hard, scratch resistant material in the first place.

RE: Incorrect
By tng on 3/22/2013 10:23:17 AM , Rating: 2
[If anyone reading this has worked with semiconductor sapphire substrates and could chime in as to how easy/difficult it was to cleave that would be appreciated]
Yes, most of the sapphire wafers that I have seen are fragile for just the reason you mention above. The structure of a single crystal wafer means that even a small hit on the edge can cause a fracture line straight across the whole wafer. The same hit on a glass wafer would cause a chip. Silicon wafers behave the same way.

I have also worked with sapphire with a silicon backing that seem to be tougher, but still fragile. The worst I seen was gallium arsenide wafers, heavy, soft and fragile.

RE: Incorrect
By 3DoubleD on 3/22/2013 3:36:03 PM , Rating: 2
Ya, I love cleaving GaAs wafers, it is so easy... you basically just have to stare at it the right way and it's done and the cleave lines are generally very clean. I hear InP wafers are similar. In my experience Si is much tougher, you have to do a much better job at scribing and notching the edges of the wafer. Even then, sometimes the Si wafers have a mind of their own and cleave in seemingly random directions (I sometimes get square pieces from a Si(111) wafer, which shouldn't be possible given the three dominant cleave directions).

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