MOSSBAUER AND MAGNETIC STUDIES OF TI-4+-SUBSTITUTED NI-ZN FERRITES

In the present work we make Mössbauer and magnetization studies of the Ti4+-substitution effect in the Ni1-yZnyFe2O4 ferrite (y=0.3 and 0.4). In this range the Mössbauer spectra are not relaxed and may be used to get an insight into the Ti4+ distribution process as well as the microscopic mechanism of anomalous magnetization. It is observed that Heff(B) remains almost constant and Heff(A) decreases as the concentration of Ti4+ ions increases in the lattice. Evidently, Ti4+ ions occupy only the octahedral B site. The nonlinear behavior of magnetization with the increase of Ti4+ ions is explained by the presence of canted spin structure. It is found that the change of the canting angle is basically due to the change in the exchange constant JNi2+(B)-Ni2+(B). This is a consequence of the positional readjustment of various cations after the entry of Ti4+ ions into the lattice. © 1990 The American Physical Society.