The Effect of Annealing Temperature on the Magnetic Properties of Mn x Co1−x Fe2O4 Ferrites Nanoparticles

Tailored design of CoxMn1−xFe2O4 nanoferrites: a new route for dual control of size and magnetic properties

“…To the best of our knowledge, the particle sizes are even smaller than those of nanoferrites with a similar Co(II) : M(II) stoichiometry (x ¼ 0.3 or 0.7) prepared by other methods reported in the literature. 22,32,36,41,42,46 These results are in accordance with those recently reported for simple MFe 2 O 4 MNPs prepared by coprecipitation using alkanolamine bases, 50 conrming the potential role of MIPA in the reduction of the particle size not only of simple but also of mixed nanoferrites.…”

“…In fact, the potentialities of this strategy to improve the structure, surface disorder and/or magnetic properties have been highlighted for the synthesis of other mixed spinel systems such as Zn x Mn 1Àx Fe 2 O 4 , Zn x Fe 1Àx Fe 2 O 4 , 30 Ni 1Àx Zn x Fe 2 O 4 , 31 etc. Various methods have been reported for the synthesis of Co x Mn 1Àx Fe 2 O 4 mixed ferrites such as the ceramic method, 32,33 calcination of layered double hydroxide precursors, 34 thermal decomposition, 35 sol-gel combustion, 36 chemical autocombustion, 37,38 the polyol method, [39][40][41][42][43] a hydrothermal route, 44,45 solidstate reactions 46 and the nonhydrolysis/seed-mediated growth method. 22 However, most of these routes required harsh conditions (high temperatures, organic solvents, and posttreatment) or originated Co-Mn ferrites featuring large particle size (typically ranging from 20 nm to large grain sizes) and/or ferromagnetic properties.…”

Effect of Silica Embedding on the Structure, Morphology and Magnetic Behavior of (Zn0.6Mn0.4Fe2O4)δ/(SiO2)(100−δ) Nanoparticles

“…The low Hc, values for the NPs with δ = 25, 50% calcined at 700 • C, indicating that these samples can be easily demagnetized in technical applications [12]. The higher H C values are related with Zn atoms, while the presence of Mn atoms in the ferrite results in a decrease of the coercive field [16,27,28]. The variation of the coercivity H c with increasing Zn-Mn ferrite content in the SiO 2 matrix is related with the change of the anisotropy constant, particle size distribution and with the magnetic domains structure of the NPs [30].…”

“…The hysteresis loops indicate low coercivity (Hc) values suggesting that the coalescence of the crystallites results in enhanced magnetic coupling and higher magnetization [16]. The H C of the spinel nano-ferrites is mainly dictated by the magnetocrystalline anisotropy, particle-particle interaction, strain, morphology and the grain sizes [27]. The M S , as well as the magnetic anisotropy of the NPs calcined at 700 and 1100 • C, increase with increasing of the Zn 0.6 Mn 0.4 Fe 2 O 4 content in the SiO 2 matrix.…”

“…The SiO 2 matrix generates stress on the surface of the ferrite particle, which will hamper the rotation of the magnetic moments from the dead layer at the surface contributing in this way to the reduction of the coercivity [13]. The magnetic anisotropy constant depends on the lattice crystalline symmetry, the crystalline anisotropy, and on particles size and shape [13,27]. The magnetocrystalline anisotropy is also affected by the distribution of the magnetic ions on the surface of the nanosized particles.…”