4f–5d Excitation Energy of Tb3+ in Solids

Excitation spectra of the D45 → 7F emission of Tb3+ were measured in Sc(or In) BO3, and Y (or Gd) BO3, Y3Ga5O12, Sc (or Y) PO4, and Sc2 (or Y2) O3 at room temperature. The 4f–5d excitation band is discriminated from the host lattice excitation band by inspecting the concentration dependences of the excitation spectra. The energy and the shape of the 4f–5d excitation band are almost the same in the lattices with the same structure. The band splittings are related to the symmetry of the crystalline field acting on Tb3+. The 4f–5d excitation band is extremely enhanced by lowering temperature to 77°K.