Effect of Nb3+ ion substitution on the magnetic properties of SrFe12O19 hexaferrites

• Published in: Journal of materials science. Materials in electronics 2019-06, Vol.30 (12), p.11181-11192
• Main Authors: Almessiere, M. A., Slimani, Y., Güner, S., van Leusen, J., Baykal, A., Kögerler, P.
• Format: Article
• Language: English
• Subjects: Anisotropy; Bohr magneton; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coercivity; Crystal structure; Fourier transforms; Hard materials; Infrared analysis; Infrared spectroscopy; Magnetic domains; Magnetic permeability; Magnetic properties; Magnetic storage; Magnetism; Magnetization; Materials Science; Optical and Electronic Materials; Permanent magnets; Recording; Recording instruments; Sol-gel processes; Substitutes
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-019-01464-0

The crystal structure and magnetic properties of SrNb x Fe 12– x O 19 (0.00 ≤  x  ≤ 0.08) nanohexaferrites (NHFs) fabricated using a sol–gel technique is presented in this study. The X-ray powder diffractometry (XRD) and Infrared spectroscopy (FT-IR) confirmed the formation of M-type hexaferrite phase. The analyses of magnetization versus applied magnetic field, M(H), were performed at room (300 K; RT) and low (10 K) temperatures. The Bohr magneton number ( n B ), saturation ( M s ) and remanent ( M r ) magnetization values increase slightly with increasing Nb 3+ content. The room-temperature values of the magnetic parameters M r  = 31.41–33.28 emu/g, M s  = 57.10–60.14 emu/g and coercivity ( H c ) between 4274 and 4540 Oe, at 10 K, magnetization data were detected that are much higher with respect to RT values: M r  = 45.96–51.06 emu/g, M s  = 94.42–95.99 emu/g. The magnetic results indicate that the samples are magnetically hard materials at both considered temperatures. The squareness ratio (SQR) is found to be around 0.50, implying single-domain NPs with uniaxial anisotropy for pristine and substituted samples. With exception, the x = 0.0 sample indicated the formation of multi-domain structure with uniaxial anisotropy at 10 K. Field cooling (FC) susceptibility measurements were applied in temperature range of 5–350 K for pristine sample and samples that contained some Nb 3+ ions. The analyses of dc susceptibility data also proved that Nb 3+ ion substitution increases the magnetization and, additionally, allows for an easier alignment of the magnetic domains. The obtained magnetic results were investigated deeply with relation to structural and microstructural properties. The observed remanent magnetization ( M r ) and coercivity ( H c ) render the products are useful for permanent magnets and high-density recording media.