Dielectric and magnetic response of SrFe12O19–CoFe2O4 composites obtained by solid state reaction

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2016-05, Vol.207, p.47-55
• Main Authors: Hilczer, Andrzej, Kowalska, Katarzyna, Markiewicz, Ewa, Pietraszko, Adam, Andrzejewski, Bartłomiej
• Format: Article
• Language: English
• Subjects: Coercive force; Conduction; Cooling; Dielectric response; Dielectrics; Exchange spring behavior; Grain boundaries; Hexaferrite-spinel nanocomposite; Magnetic properties; Magnetization; Mathematical models; Solid state
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2016.02.003

•SrFe12O19–CoFe2O4 nanocomposites with exchange spring behavior are synthesized.•The exchange coupling is optimized for hard:soft magnetic wt. ratio of 4:1.•Dielectric response of the composites is similar to those of other ferrites.•Dielectric and electric properties are described within the Koops model. Nanocomposites of hard magnetic SrFe12O19 hexaferrite and soft magnetic CoFe2O4 spinel with exchange spring interaction were obtained by simple solid state reaction during 8h and 14h at 1050°C. The structure and morphology of the composites was characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Dielectric and electric response of the composites were found to be similar to the behavior of other ferrites and can be well described within the Koops model of the ceramic consisting of highly conducting grains separated by poorly conducting grain boundaries. Single-phase magnetic hysteresis loops obtained for SrFe12O19/CoFe2O4 composites with weight ratio 4:1 containing ∼1wt.% hematite. The difference in magnetization below the temperature of irreversibility, measured in field cooling and zero field cooling experiments in fields exceeding doubled coercivity, was found to be greater for composites synthesized during 4–14h than that obtained for 22h.