Luminescence of Some Impurity Magnetic Ions in A1N

Abstract

The luminescence properties of A1N: Mn and A1N: Eu²⁺ have been investigated under laser and non-laser excitation. The excitation spectra of powders of A1N: Mn consist of a broad band and several narrow bands in the visible range. We have connected these narrow bands to transitions among energy levels of the 3d electrons, while the broad UV band is caused by transfer of excitation energy from oxygen centres to Mn centres. Emission and excitation spectra of all powdered samples of A1N: Eu²⁺ consist of broad bands in the visible or UV regions, respectively. We have ascribed these bands to the 4f⁷ ⇄ 4f⁶5d transitions of the Eu²⁺ ions. The luminescence properties depend strongly on Eu2+ concentration, so the luminescence of the samples with concentrations below and above 0.3 mol % is quite different. There probably exist three Eu²⁺ sites in A1N which have the same Eu²⁺ central ions, but a different environment. For example, the nitrogen ions can be replaced by oxygen ions; this would result in various splittings of the 5d level.