Crystalline Fields of Pr, Nd and Yb from Paramagnetic Susceptibilities

Abstract

Calculations are made on the temperature variation of the paramagnetic susceptibilities of various salts of the rare earth group, employing the ideas of the crystal field developed in previous papers. It is shown that good agreement can be obtained with the experimental results on the salts ${\mathrm{Pr}}_2$ ${\left(\mathrm{S}{\mathrm{O}}_4\right)}_3$, ${\mathrm{Nd}}_2$ ${\mathrm{O}}_3$ and ${\mathrm{Yb}}_2$ ${\mathrm{O}}_3$, if the crystalline field is assumed to have the form ${\Sigma }_i\{A{x_i}^2+B{y_i}^2-(A+B\left)\mathrm{}{z_i}^2\right\}$. This type of field, however, allows no agreement to be had for the experimental data on ${\mathrm{Pr}}_2$ ${\left(\mathrm{S}{\mathrm{O}}_4\right)}_3$·8${\mathrm{H}}_2$O; instead for the octahydrated sulphates, the assumption of a field of cubic symmetry $D{\Sigma }_i({x_i}^4+{y_i}^4+{z_i}^4)$ is necessary. The various crystalline fields we find necessary to account for the magnetic data are in good accord with the few facts known on the crystal structure of the different compounds.