EFFECT OF ALUMINUM SUBSTITUTION ON THE DIFFUSION-COEFFICIENT AND JUMPLENGTH OF ZINC FERRITE

Polycrystalline samples of mixed ferrite ZnAlxFe2-xO4, where x = 0, 0. 3, 0.6, 0.9 and 1.2 have been prepared. The jump length of electrons i n the octahedral site and conductivity were studied as a function of a luminium substitution. The decrease of the jump length and decrease of bulk density with aluminium concentration is attributed to the substi tution of Fe3+ for Al3+ which has a smaller atomic radius and lower at omic weight than Fe3+. The nonmagnetic Al3+ ions substitute Fe3+ ions and reduce the exchange electrons between ferric and ferrous ions and thereby reduce the conductivity and mobility. The increase of aluminiu m concentration decreases the diffusion coefficient of vacancies which is the predominant role for densification during sintering.