The Effect of 'Hydrogenation – Recalcination' Cycling on the Magnetic Properties of Strontium Hexaferrite

Abstract

Strontium hexaferrite powder synthesized conventionally was treated in a hydrogen atmosphere and then recalcined in air. This process had a marked effect on the microstructure and on the magnetic properties of the initial sample. The process was repeated several times and the effects investigated. The results showed that the products of the treatment prior to recalcination are Fe and Sr7Fe10O22 and this resulted in a change in magnetic properties from hard to soft. Consequent calcination, resulted in the reformation of strontium hexaferrite but now with a much finer grain size. This resulted in a significant enhancement of the coercivity. The variation of the coercivity with the number of cycles indicated a maximum value of 413 kA/m which then remained constant with subsequent cycling.