Lanthanide 4f-level location in AVO(4):Ln(3+) (A = La, Gd, Lu) crystals.

The spectral properties of LaVO(4), GdVO(4) and LuVO(4) crystals doped with Ce(3+), Pr(3+), Eu(3+) or Tb(3+) have been investigated in order to determine the position of the energy levels relative to the valence and conduction bands of the hosts along the trivalent and divalent lanthanide series. Pr(3+) and Tb(3+) ground state levels are positioned based on the electron transfer energy from those states to the conduction band, the so-called intervalence charge transfer (IVCT). This approach is compared with an alternative model that is based on electron transfer from the valence band to a lanthanide.