Corundum-based transparent infrared absorbers

Hypothetical corundum-based compounds are studied by electronic structure calculations. One quarter of the Al atoms in Al2O3 is replaced by a 3d transition metal from the M = Ti, … , Zn (d1, … , d9) series. Structure optimisations are performed for all the M–Al2O3 compounds and the electronic states are evaluated. Due to the M substitutes, narrow partially filled bands are formed at the Fermi energy. Beyond, for M = Ni and M = Cu the optical properties of Al2O3 in the visible range are conserved, while for M = Ti, … , Co the systems form high accuracy optical filters. Since the compounds absorb the infrared radiation, the M = Ni and M = Cu systems are good candidates for heat-protective coatings.