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

• Published in: Advanced electronic materials 2024-09, Vol.10 (9), p.n/a
• Main Authors: Laursen, Amalie P., Frandsen, Jens P., Shyam, Priyank, Mørch, Mathias I., Gjørup, Frederik H., Vijayan, Harikrishnan, Jørgensen, Mads R. V., Christensen, Mogens
• Format: Article
• Language: English
• Subjects: Chemical Sciences; combined texture and Rietveld analysis; electron backscatter diffraction; in situ X-ray diffraction; Kemi; Materialkemi; Materials Chemistry; Natural Sciences; Naturvetenskap; permanent magnets; strontium hexaferrite; ultrafast sintering
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.202400077

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 (BHmax) of 18.6(8) kJ m−3. The formation of a strontium hexaferrite magnet from cold compacted goethite and strontium carbonate is studied using in situ synchrotron powder X‐ray diffraction (PXRD) with a 16‐ms time resolution. Texture with the c‐axis parallel to the pressing direction prevailed through the iron oxide phase transitions. Strontium hexaferrite formed within seconds at 1173 K. The resultant magnet has an energy product (BHmax) of 18.6(8) kJ m−3.