CLUSTER AND MAGNETIC-STRUCTURES OF THE LI-TI-ZN FERRITE SYSTEM STUDIED BY POLARIZED NEUTRONS

The magnetic structure of Li-Ti-Zn ferrite when annealed and slowly co oled down exhibits the presence of magnetic clusters which arise due t o thermal diffusion of Li, Fe, and Ti ions. The same material annealed above 1300 K and rapidly cooled down has no clusters. The polycrystal line sample with chemical formula Li0.673Zn0.3Mn0.05Ti0.695Fe1.282O4 i s studied by the polarized neutron diffraction and low-angle scatterin g methods. The cation distributions are determined for samples with an d without cluster structure. The mean cluster diameter and their magne tic moment are evaluated as D = (6.6 +/- 0.1) nm and M(c) = (880 +/- 1 20) mu(B), respectively. Basing on the neutron diffraction reflections (220) and (400) the magnetization process is studied for both samples . Analysis of the cluster structure magnetization is carried out using a modified Langevin function containing the magnetic cluster interact ion. The value of the cluster magnetic moment determined in this way b y a fitting procedure is equal to M(c) = (800 +/- 10)mu(B).