Hexagonal M-type strontium ferrite SrFe12O19 is widely used as permanent magnets, because of its high performance-to-cost ratio and good chemical stability.
The ferrite magnets are processed by powder metallurgy, that is, hexaferrite powders are first pressed (usually under magnetic field) and then sintered. This complex process can lead to variations in the properties of the finished products. During the sintering step, several parameters have to be taken into account, among which temperature, time and atmosphere. Many studies pointed out that the best sintering conditions are obtained with a 1200°C temperature under oxidative atmosphere.
Unfortunately, some applications imply to co-sinter hexaferrite with another material which may be sensitive to oxidation. It is known that sintering atmosphere may affect magnetic properties of ferrite. In this work, the influence of non-oxidative sintering atmosphere on hexaferrite crystallographic structure has been studied. Strontium hexaferrite samples have been sintered under vacuum, nitrogen, and argon.