Spectroscopic and crystal field studies of LiAlO2:Mn2+ single crystals

LiAlO2:Mn2+ high-quality single crystals were grown by Czochralski technique. Room-temperature excitation and emission spectra were recorded in the spectral range from 220 to 750 nm. For the first time, detailed crystal field analysis (based on the exchange charge model of crystal field) has been performed for Mn2+ ions in this host. Calculated crystal field parameters were used for diagonalization of the crystal field Hamiltonian in the basis set consisting from all wave functions of the LS terms of Mn2+ ions. Calculated positions and splittings of the Mn2+ energy levels are in good agreement with main peaks in the experimental excitation and emission spectra and widths of the observed spectral bands. It was established from the symmetry analysis of the Li+ and Al3+ positions that the former can be described by the C2 point group, whereas the latter by the D2 point group.