Luminescence of the Bi3+ Ion in Compounds LiLnO2 and NaLnO2    ( Ln = Sc ,  Y  , La , Gd , Lu )

The luminescence properties of the Bi3+ ion as an activator in the series of compounds and vary considerably with the host lattice composition. The Stokes shift of the emission varies from 1500 cm−1 in the case of to 12,800 cm−1 in the case of . The large variation of the position of the emission band is ascribed to a Jahn‐Teller effect in the excited state of the Bi3+ ion resulting in different kinds of minima on the 3P APES. The internal pressure on the Bi3+ ion, caused by the differences in the ionic radii of the trivalent cations, can explain the variation in the relative depths of the minima. The Stokes shift of the emission is inversely proportional to the energy difference between the and the excited levels. For small Stokes shifts we observed vibrational structure in the spectra. The vibrational modes involved are ascribed to more or less localized modes of the octahedron.