Point-charge approximation of trigonal Tm2+and Yb3+centres in crystals of CaF2structure
- 2 February 1978
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 11 (4) , 725-734
- https://doi.org/10.1088/0022-3719/11/4/016
Abstract
The point-charge approximation is extended to trigonal centres of Tm2+ and Yb3+ (both 4f13) in fluorite-type crystals: Tm2+ in CaF2, SrF2 and BaF2; Yb3+ in CaF2, SrF2, BaF2, CeO2 and ThO2. The perturbation to the cubic field at the incorporation rare-earth ions is treated as a Coulomb field of a compensating point charge. The wavefunctions of trigonal centres are calculated by diagonalising an approximate 3*3 perturbation matrix of the compensating ion. Calculated g-values for Yb3+ with the nearest neighbour and next nearest neighbour compensation, respectively, are in reasonable agreement with experimental results, whereas g-values for Tm2+ are in good agreement with experiment provided that unestablished compensation is due to a divalent ion at the next nearest neighbour site. Expressions for axial g-values are also obtained in terms of power-series expansion of the perturbation and are compared with experimental g-values.Keywords
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