The effect of strontium dissolution by milling in water on the magnetic properties of strontium hexaferrite

The milling in or the simple contact with water of strontium hexaferrite powders produces a loss of stromtium ions which amounted to about 10% from the total amount present in ferrite when the stoichiometric compound was wet milled for 10 h. The magnetic moment of these powders decreased by as much as 10% compared to the similarly milled samples in alcohol whose chemical composition was not effected by the milling medium. The Curie temperature of the Sr deficient samples was also lower than that of the stoichiometric ones. The experimental results are discussed in terms of the modications of the superexchange interaction between the octahedral iron on the 4f and 12k sublattices, brougth about by the possible loss of oxygen atoms from the 12K sites which leave the lattice together with the Sr ions in orfer to compensate for the electric charge.