CRYSTAL-FIELD SPLITTING OF ENERGY-LEVELS OF RARE-EARTH IONS DY3-5(PO4)(3)F((4F(9)) AND YB3+(4F(13)) IN M(II) SITES IN THE FLUORAPATITE CRYSTAL SR)

We have calculated a set of crystal-field parameters, B-nm, for Dy3+ t hrough Yb3+ ions in M (II) sites in the crystal Sr-5(PO4,)(3)F (SFAP). The B-nm parameters were derived from lattice-sum calculations and fr om analyses of the optical spectra reported for Ho3+, Er3+, and Tm3+, individually doped into SFAP. These parameters were used to predict st arting values, which were then semiempirically fitted for the crystal- field splitting of the multiplet manifolds of the sextet states of Dy3 +(4f(9)), H-6(J) and F-6(J),and the doublet states of Yb3+(4f(13)) hav ing manifolds F-2(7/2), and F-2(5/2). The compared with an analysis of the absorption and fluorescence spectra of Dy3+ and Yb3+ individually doped into SFAP. The rms deviation between 44 calculated and observed Stark levels of Dy3+ in Dy:SFAP is 10 cm(-1). Without fitting of any parameters, the predicted crystal-field splitting of the Yb3+ multiple t manifolds is in reasonable agreement with the observed spectra for Y b:SFAP. (C) 1998 American Institute of Physics. [S0021-8979(98)06402-0 ].