Measurement of exchange interaction in Ti-substituted Ni-ferrites

A series of Ni1+xTixFe2−2xO4 ferrites (x=0.0, 0.05, 0.1, 0.15, 0.2) were prepared by standard ceramic technique. The X-ray diffraction results confirm the presence of an fcc phase. The variation of lattice constant with Ti concentration follows Vegardʹs law. The magnetic susceptibility of Ni1+xTixFe2−2xO4 ferrites was measured over a temperature range of 250–573 K using mutual inductance technique. Above the Curie temperature (Tc), the susceptibility follows a Curie–Weiss law with a negative characteristic temperature. Below the paramagnetic Curie temperature, all the samples show a deviation from the Curie–Weiss law. The effective magnetic moment, Peff, the characteristic temperature, θ, the exchange interaction, J/K, decreases with the increase in the Ti concentration, which is attributed to the weakening of the A–B interaction due to the presence of triangular spin arrangements of the Y–K type on the B-sublattice.