Luminescence Properties of Al 2 O 3 :Ti in the Blue and Red Regions: A Combined Theoretical and Experimental Study.

Using jointly experimental results and first-principles calculations, we unambiguously assign the underlying mechanisms behind two commonly observed luminescence bands for the Al 2 O 3 material. Indeed, we show that the red band is associated with a Ti 3+ d - d transition as expected, while the blue band is the combination of the Ti 3+ + O - → Ti 4+ + O 2- and V O • + e - → V O × de-excitation processes. Thanks to our recent developments, which take into account the vibrational contributions to the electronic transitions in solids, we were able to simulate the luminescence spectra for the different signatures. The excellent agreement with the experiment demonstrates that it should be possible to predict the color of the material with a CIE chromaticity diagram. We also anticipated the luminescence signature of Al 2 O 3 :Ti,Ca and Al 2 O 3 :Ti,Be that were confirmed by experiment.