Remember Star Trek IV, The Voyage Home and Scottys formula for - TopicsExpress

Remember Star Trek IV, The Voyage Home and Scottys formula for Transparent Aluminum? It turns out that a 1980 patent for Aluminium oxynitride is a close match. (AlN)x·(Al2O3)1-x, 0.30 ≤ x ≤ 0.37 Denser than Glass at 3.19, Refractive Index of 1.79. 4 times harder than fused silica glass and as hard as sapphire (Al2O3). The only problem is that it is almost as expensive as synthetic sapphire. And being a ceramic, it is probably brittle. It turns out, there is some real stuff. Aluminium oxynitride en.wikipedia.org/wiki/Aluminium_oxynitride