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, Mossbauer spectroscopy and magnetization measurements at various temperatures. EPR spectra of these samples comprise generally a broad and asymmetric EPR signal. The variation of g(eff) and peak-to-peak line width Delta H-pp, with Ti concentration and temperature are attributed to the variation of dipole-dipole interaction and the superexchange interaction. Mossbauer 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 H-eff 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. (C) 2007 Elsevier B.V. All rights reserved.