Open AccessTowards bi-magnetic nanocomposites as permanent magnets through the optimization of the synthesis and magnetic properties of SrFe12O19 nanocrystallites
Author(s) -
Pierfrancesco Maltoni,
Tapati Sarkar,
G. Varvaro,
G. Barucca,
С. А. Иванов,
Davide Peddis,
Roland Mathieu
Publication year - 2021
Publication title -
journal of physics. d, applied physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.857
H-Index - 198
eISSN - 1361-6463
pISSN - 0022-3727
DOI - 10.1088/1361-6463/abd20d
Subject(s) - coercivity , crystallite , materials science , annealing (glass) , nanocomposite , magnet , condensed matter physics , nanotechnology , transmission electron microscopy , nanoparticle , chemical engineering , magnetic anisotropy , remanence , magnetic nanoparticles , magnetization , composite material , magnetic field , metallurgy , physics , quantum mechanics , engineering
Sol–gel synthesis was used in order to obtain nanocrystallites of the SrFe 12 O 19 (SFO) hexaferrite in an efficient and reliable way. By optimizing the initial synthetic conditions, we were able to control the size of the nanoparticles (NPs), at lower annealing temperature. The x-ray powder diffraction, transmission electron microscopy (TEM), and magnetic measurements have demonstrated a significant relation between the morphology, size, and magnetic properties of the nanoscale SFO, revealing a definite dependence on the crystallite size along the c -axis. The obtained NPs appear almost isotropic, in the form of platelets and exhibit similar magnetic performance, in terms of the energy product (BH) MAX , thus, demonstrating the suitability of reducing the annealing temperature without any deterioration in the magnetic properties. Additionally, this work illustrates the feasibility of the sol–gel bottom-up approach to employ magnetic NPs as building-blocks for designing hard/soft exchange-coupled bi-magnetic nanocomposites, combining the high coercivity of a hard phase (SFO) and the high saturation magnetization of a soft phase (CoFe 2 O 4 ); in this regard, we discuss the tunability of the magnetic anisotropy by symbiotically restricting the growth of both phases.