Mössbauer Studies on Hyperfine Interactions in Titanium Substituted Lithium Ferrites

Mössbauer spectra of Li0.5so+0.5xTix Fe2.5-1.5xO4, with x ranging from 0 to 1.2 are obtained at 300 and 78 K. Well defined hyperfine Zeeman spectra are observed for samples with x ≦ 5 0.6 at 300 K and for x ≦ 0.8 at 78 K and resolved into two sextets corresponding to octahedral and tetrahedral sites. The samples with x = 0.2 to 0.6 show a central doublet a t both the temperatures which is attributed to the presence of superparamagnetic clusters. Relaxation effects are observed for the samples with r = 0.8 and 1.0 at 300 K and with x = 1.0 and 1.2 at 78 K, while the sample with x = 1.2 at 300 K exhibits paramagnetic behaviour. There is no change in isomer shift with increasing Ti4+ substitution. The decrease in the magnetic field at 57Fe nucleus is explained in terms of exchange interactions and a canted spin arrangement on the tetrahedral sublattice.