Enhancing the strain sensitivity of CoFe₂O₄ at low magnetic fields without affecting the magnetostriction coefficient by substitution of small amounts of Mg for Fe

Abstract

Attaining high magnetostrictive strain sensitivity (dλ/dH) with high magnetostriction strain (λ) is desirable for sintered polycrystalline cobalt ferrite for various applications. It is shown that substitution of a small amount of Fe(3+) by Mg(2+) in CoMgxFe2-xO4 (x < 0.1) gives a comparable maximum magnetostriction coefficient to that of the unsubstituted counterpart, with large improvement in the strain sensitivity at relatively low magnetic fields. A large increase in the magnetostriction coefficient is obtained at low magnetic fields for the substituted compositions. The magnetostriction parameters are further enhanced by magnetic field annealing of the sintered products. The results are analyzed based on powder XRD, Raman spectroscopy, XPS and magnetic measurements and based on the results from these studies, the changes in the magnetostriction parameters are correlated with the changes in the cation distribution, magnetic anisotropy and microstructure.

Atomic-scale mechanisms for magnetostriction in CoFe2O4 and La0.5Subı́as1, Cuartero2, García3 et al. 2019Phys. Rev. B9030View full textAdd to dashboardCite

“…4(a)) corresponds to the longer interatomic distance detected by EXAFS, that is the Co-Fe Td one (Table I). Moreover, the sign of all the magnetostrictive strains is negative in agreement with that of the macroscopic measurements [21][22].…”

“…S4(b and DR FeOhCo(Fe)Oh /R FeOhCo(Fe)Oh ≈ -200×10 -6 . The sign of all the magnetostrictive strains is also negative in agreement with that of the Co atom and the macroscopic measurements [21][22]. At room temperature, the magnitude of the magnetostrictive strains for the Fe atoms is reduced by a factor around 2.2.…”

“…This value is markedly higher than those obtained from the macroscopic measurement in single crystals either at room temperature λ 100 ≈ -500 ppm or at 2 K, λ 100 ≈ -730 ppm [7]. However, the values of the DiffEXAFS strains DR/R for higher-order coordination shells around Co decrease with increasing the interatomic distance yielding values much more comparable to the macroscopic magnetostriction for polycrystalline CoFe 2 O 4 that is reported to vary between -200 and -400 ppm [21,22].…”

Magnetic and spectroscopic properties of Ni–Zn–Al ferrite spinel: from the nanoscale to microscale

“…Further, the highest magnitude of magnetostriction, l max ¼ À10 ppm, was achieved for sample annealed at 1200 C. The magnetostrictive properties depends upon the processing parameters such as synthesis method, applied pressure while making pellets, sintering atmosphere, temperature and sintering time. 65 However, the observed porous nature may be responsible for the decrease of magnetostrictive coefficient in nanoparticle samples. Also, another possibility is that the increase in the magnetostriction with sintering temperature can be due to the minor changes in the degree of inversion in the ferrite, which can be attributed to the increase super-exchange and the direction deection of the magnetic domain would, therefore, result in a higher magnetostriction.…”

Dynamic Magnetostriction of CoFe2O4 and Its Role in Magnetoelectric Composites

“…This can be done by magnetic annealing [11][12][13][14][15], magnetic-field-assisted compaction [16,17], or reaction under uniaxial pressure [18]. Another way to tune magnetostrictive properties of CoFe 2 O 4 is by substitution of the Fe atoms by Mg, Al, Ti, Mn, Ni, Cu, Zn, Ga, Zr, Nb, In, etc., or even rare-earth elements [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Moreover, there is an increasing interest in synthesizing cobalt ferrite from recycled Li-ion batteries to use it in magnetostrictive applications [25,[34][35][36].…”