Aligned Permanent Magnet Made in Seconds–An In Situ Diffraction Study

Abstract

The synthesis of a strontium hexaferrite magnet is studied using in situ synchrotron powder X-ray diffraction (PXRD) with a 16-ms time resolution. The precursor material is cold compacted shape-controlled goethite and strontium carbonate. The time evolution of the phases is modeled with sequential Rietveld refinements revealing that strontium hexaferrite forms within seconds at ≈1173 K. Texture analysis is performed on selected PXRD frames throughout the experiment, and the preferred orientation introduced by cold-pressing goethite prevails through the iron oxide phase transitions (goethite → hematite → strontium hexaferrite). Electron backscatter diffraction (EBSD) data on the final pellet confirms the preferred orientation observed with PXRD. The resulting magnet has respectable magnetic properties, considering the simplicity of the preparation method, with an energy product (BH_max) of 18.6(8) kJ m⁻³.