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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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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.

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