Luminescence properties of Pr3+ and Sm3+ ions in natural apatites

The luminescence spectra of Pr3+ and Sm3+ ions in apatite Ca-5[Fa (PO4)(3)] pound crystals from Spain and Russia have been compared with those for phosphate glasses doped with Pr3+, Sm3+ and Pr3+, Sm3+ ions. Time-resolved spectra measurements confirm that, in apatites, samarium ions occupy two non-equivalent crystal sites; the same is assumed for praseodymium ions. For the first time in minerals, the Stark splitting energy levels Delta E for H-3(6) and D-1(2) of Pr3+ ion and H-6(7/2) of Sm3+ ion were determined. Some small differences in Delta E values for the Spanish and Russian apatite are discussed. The decay times of the excited levels of Pr3+, Sm3+ and Pr3+, Sm3+ doped in phosphate glass were measured at room temperature and at 77 K. The energy transfer process between samarium and praseodymium ions was observed and the energy transfer rate was calculated.