Aluminum oxynitride spinel(A1ON)which exhibits excellent optical and mechanical properties has been obtained increased attention as leading candidate for transparent armor.The incorporation of nitrogen into an aluminum oxide stabilizes a spinel phase.Due to its cubic crystal structure,A1ON is an isotropic material that can be produced transparent as a polycrystalline material.Transparent AlON ceramics is normally manufactured by Alon powder,which is synthesized by carbon thermal reduction of Al2O3.