Energy level location of divalent and trivalent lanthanides in calcium aluminosilicate materials

Ca 2 Al 2 SiO 7 (CAS) doped with Eu 3+ , Ce 3+ , and Tb 3+ ions (1 mol%) were synthesized by solid-state reaction at 1280 °C and spectroscopic studies of the prepared samples were performed by photoluminescence and photoluminescence excitation spectra at room temperature. Energies of the lowest f-d transition of Ce 3+ ions and charge transfer process of Eu 3+ ions obtained from photoluminescence excitation spectra were used to predict the energy levels of all divalent and trivalent lanthanides relative to the valence and conduction bands of CAS host lattice and to construct the host referred binding energy and vacuum referred binding energy schemes. The predicted energies for Tb 3+ ions are in good agreement with experimental energies indicating the obtained energy level scheme provides a better understanding of the luminescent processes in Ca 2 Al 2 SiO 7 material.