Crystal-field splitting of energy levels of rare-earth ions Dy3+(4f9) and Yb3+(4f13) in M(II) sites in the fluorapatite crystal Sr5(PO4)3F

We have calculated a set of crystal-field parameters, B-nm, for Dy3+ through 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 from analyses of the optical spectra reported for Ho3+, Er3+, and Tm3+, individually doped into SFAP. These parameters were used to predict starting 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)) having 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+ multiplet manifolds is in reasonable agreement with the observed spectra for Yb:SFAP. (C) 1998 American Institute of Physics. [S0021-8979(98)06402-0].