Luminescence in the System Al[sub 2]O[sub 3]-AIN

Aluminum nitride and aluminum oxide are mutually soluble at high temperatures. A number of solid solutions and reaction products of various compositions in the system have been prepared at about 2000°C, which can be described by one general formula where represents the number of nitrogen atoms. Five phases were observed: (i) of corundum structure with negligible solubility of ; (ii) a phase similar to δ‐alumina, found when the content was about 5.5 mole %; (iii) a spinel phase with an content up to 50 mole %; (iv) a phase obtained when the content was between 50 and 67 mole % (this phase always occurred mixed with phase iii); (v) of wurtzite structure with up to about . Phases (ii) to (v) show no observable fluorescence, but broad band phosphorescence in the blue when excited with 2537Aå radiation. Manganese activation produces a green or a red luminescence which is attributed to transitions of Mn 2+ and Mn 4+ at different lattice sites. Electroluminescence in the visible is observed in all phases when suitably activated.