07-12-2018, 06:43 AM
Actually, if we area going to allow the aluminum oxide passivation layer to count as transparent aluminum then we may as well go all in and include un-doped sapphire and aluminum oxy-nitride which also is transparent in bulk and used as armored glass in some military vehicles. It is pretty remarkable stuff but close to sapphire in properties and very hard to fabricate. Aluminium oxynitride.