Formation of lead-bearing ferrite in aqueous suspension by air oxidation

Abstract

A Pb-bearing ferrite with spinel-type structure, Pb_0.19Fe_2.75O_4.0, was obtained by air oxidation of an aqueous suspension, with an initial Pb²⁺: Fe_tot. mol ratio of 0.30 : 1, at pH 12 and 65 °C. This Pb-bearing ferrite is formed by the transformation of an intermediate compound, which is stable in a nitrogen atmosphere, during air oxidation. The Curie point of the Pb-bearing ferrite was estimated to be ca. 400 °C. When the Pb²⁺: Fe_tot. mol ratio in the initial reaction solution was <0.20 : 1 at pH 12, α-FeO(OH) was formed together with the Pb-bearing ferrite.