Synthesis and magnetic properties of hard/soft SrFe12O19/Ni0.7Zn0.3Fe2O4 nanocomposite magnets

• Published in: Journal of magnetism and magnetic materials Vol. 324; no. 19; pp. 3094 - 3098
• Main Authors: Radmanesh, M.A., Seyyed Ebrahimi, S.A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2012; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dipolar interaction; Exact sciences and technology; Exchange and superexchange interactions; Exchange coupling; Exchange spring behavior; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Materials science; Materials synthesis; materials processing; Nanocomposite magnets; Physics; Reduced remanence; Studies of specific magnetic materials; Dipolar interaction; Reduced remanence; Exchange coupling; Exchange spring behavior; Nanocomposite magnets; Hexagonal ferrites; Ferromagnetic materials; Strong coupling; XRD; Soft magnetic materials; Dipole interactions; Magnetic measurement; Hysteresis loop; Composite materials; Nanocomposites; Iron Strontium Oxides Mixed; Microstructure; Sol-gel process; Exchange interactions; Magnetic properties
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2012.05.008

Magnetic nanocomposite SrFe12O19/Ni0.7Zn0.3Fe2O4 powders with different weight fractions of the Ni0.7Zn0.3Fe2O4 soft ferrite were synthesized by a combination of the sol–gel self-propagation and glyoxilate precursor methods. The results of magnetic measurements revealed the higher Mr/Ms ratio for the nanocomposites than that for the single phase SrFe12O19 which proves the existence of the intergrain exchange coupling between hard and soft magnetic phases with the exchange spring behavior. The highest Mr/Ms ratio of 0.63 was obtained in the composite consisting of 80wt% of SrFe12O19 and 20wt% Ni0.7Zn0.3Fe2O4. The microstructural studies of this sample exhibited the average dimensions of hard and soft phases about 20nm and 15nm, respectively which are small enough for strong exchange coupling according to the theoretical studies. The variations of the reduced remanence (Mr/Ms) with increasing the weight fraction of the soft phase could be also explained by the role of the exchange and dipolar interactions in tuning the magnetic properties of the nanocomposites. ► In this work the effect of different weight fraction of soft phase on the exchange spring behavior of the SrFe12O19/Ni0.7Zn0.3Fe2O4 nanocomposite synthesized with a new method was investigated.