Magnetic study of Ti-substituted NiFe2O4 ferrite

The Ni1+xTixFe2−2xO4 (0 ≤ x ≤ 0.1) ferrite systems prepared by a semi-chemical route, have been studied by electron paramagnetic resonance (EPR) at X-band, Mössbauer spectroscopy and magnetization measurements at various temperatures. EPR spectra of these samples comprise generally a broad and asymmetric EPR signal. The variation of geff and peak-to-peak line width ΔHpp, with Ti concentration and temperature are attributed to the variation of dipole–dipole interaction and the superexchange interaction. Mössbauer spectra comprise two sets of sextet attributed to Fe3+ at two distinct sites-A and -B. Ti4+ ions are concluded to occupy the octahedral B-sites. Magnetic moment is found to decrease with the increase of Ti4+ concentration. The effective magnetic field Heff at the A-sites also follows a similar trend. The reason is attributed to the canted structure of spins in the Ti-doped samples. An anomalous behavior at x = 0.015 is observed in the properties studied here and some sort of phase change is believed to occur at 473 K in these ferrites.