RELAXATION-TIME STUDIES ON NI0.07ZN0.3ALXFE2-XO4 AND NI0.7ZN0.3CRXFE2-XO4

The effect of substitutions of Al3+ and Cr3+ on tau(m) in Ni-Zn ferrit es prepared using usual ceramic technology has been investigated. The relaxation time tau(m) for the system of ferrites Ni0.7Zn0.3AlxFe2-xO4 and Ni0.7Zn0.3CrxF2-xO4 increases with the increase in the Al3+ and C r3+ content. This is attributed to an increase in the resistivity. An increase in tau(m) with Al3+ and Cr3+ suggests that the response of th e material to the field variation is slowed down, i.e. these substitut ions cause hinderance to the domain wall motion. From the observation that the rate of change of tau(m) with Al3+ substitutions is greater t han that with Cr3+ substitutions, it can be concluded that Al3+ causes more hinderance to the domain wall motion than Cr3+ ions. (C) 1998 El sevier Science S.A.