Paramagnetic Scattering of Neutrons by Rare Earth Oxides

The magnitude and angular dependence of the paramagnetic scattering of neutrons has been studied for the trivalent ions in the rare earth oxides, ${\mathrm{Pr}}_2$ ${\mathrm{O}}_3$, ${\mathrm{Nd}}_2$ ${\mathrm{O}}_3$, and ${\mathrm{Er}}_2$ ${\mathrm{O}}_3$. These rare earth ions have large angular momentum contributions to their magnetic moments and one object of the investigation was to obtain a better understanding of the magnetic scattering in such cases. The angular distribution of the scattering for samples at room temperature is compared with the theoretical results of Trammell which are given in the following paper. The calculations based on screened hydrogenic wave functions give results in reasonably good accord with the measurements when the screening constant is taken as an adjustable parameter which is then determined, within limits, by the data. Scattering measurements were also made at liquid nitrogen and liquid hydrogen temperatures, and within a few percent no changes and, hence, no crystalline field or exchange effects were observed.