PARAMAGNETIC-SUSCEPTIBILITY SIMULATIONS FROM CRYSTAL-FIELD EFFECTS ONRARE-EARTH ANTIMONATES R3SB5O12

The magnetic susceptibilities of polycrystalline rare earth antimonate s R3Sb5O12 (R = rare earth), with cubic structure, space group (I) ove r bar 43m (No. 217), where the point site symmetry of R is S-4, have b een measured from 4.2 to 800 K. Using the wave functions and energy le vels derived from standard free ion and crystal field parameters deduc ed from the analysis of the optical spectra of purl and/or doped Pr, N d, Eu and Er compounds, the calculation of the temperature dependent p aramagnetic susceptibility has been carried out according to the Van V leck formalism. The same calculation through crystal field parameters resulting from the ab initio simple overlap model over the entire R3Sb 5O12 series has been performed. Curves of both kinds were very similar for each configuration, with the exception of those for the Pr compou nd. Very good agreements with experimental data are found, especially below around 400 K, even when the approximate D-2d (near S-4) potentia l is considered. The standard crystal field treatment of 4f(N) configu rations is shown to explain the magnetic properties of these compounds with no need to consider any sort of magnetic interaction between the magnetic ions.