Tuning of the magnetostrictive properties of cobalt ferrite by forced distribution of substituted divalent metal ions at different crystallographic sites

Abstract

Comparative studies have been made to understand the role of different crystallographic site preferences of the substituted non-magnetic divalent metal ions in the magnetostrictive properties of cobalt ferrite, by substitution of Zn2+ and/or Mg2+ for Fe3+ in CoMgxFe2−xO4, CoZnxFe2−xO4, and CoMgx/2Znx/2Fe2−xO4 (0.0 ≤ x ≤ 0.2). Detailed Raman spectral and magnetic characterizations are made to extract the information on the tetrahedral/octahedral site preferences of Zn and Mg in the spinel lattice of cobalt ferrite. The structural, microstructural, magnetic, Raman spectral, and magnetostrictive parameters of the studied compositions show distinguishable variations for x < 0.1 and x ≥ 0.1. Co-substitution of a small amount of Mg and Zn for Fe in CoMgx/2Znx/2Fe2−xO4 (x < 0.1) showed relatively larger strain sensitivity, [dλ/dH]max (−2.6 × 10−9 mA−1 for x = 0.05), higher than that for the Mg-substituted samples (−2.05 × 10−9 mA−1 for x = 0.05) and comparable to that for the Zn-substituted samples (−2.47 × 10−9 mA−1 for x = 0.05), without much drop in the maximum value of magnetostriction, λmax (−189 ppm for x = 0.05) compared to that for the unsubstituted counterpart (−221 ppm). The results show that it is possible to obtain high strain sensitivity (at fields <50 kA/m), along with high magnetostriction strain at low magnetic fields (∼250 kA/m), by tuning the distribution of the substituted cations in the tetrahedral and octahedral sites of the cobalt ferrite lattice.

Enhanced piezomagnetic coefficient of cobalt ferrite ceramics by Ga and Mn doping for magnetoelectric applications

“…Namely, magnetostriction is negative along the magnetization easy axis that dominates response in the low field regime (negative coefficient), while it is positive along the hard axis that gives an opposite contribution that only becomes apparent above a certain field (positive coefficient). 25,42 Overall, magnetostriction is larger along the easy axis and thus, a final contraction result. Maximum magnetostriction and its corresponding magnetic field both decreased with doping, either Ga or Mn, which is in accordance with previously reported results.…”

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].…”

The Cation Distributions of Zn-doped Normal Spinel MgFe2O4 Ferrite and Its Magnetic Properties

“…The direct imaging of atomic structures, especially in the site preference of substituted ions, is vital for magnetic materials to correctly explain their magnetic performance and provide guidance for potential commercial applications, including microwave devices, magnetic storage media, ferrofluids and biomedical devices [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. It is known that the structural, electrical and magnetic properties of materials are highly sensitive to the conditions of their preparation, compositions and magnetic interactions, which strongly depend on the distribution of cations [ 8 , 9 , 10 , 11 , 12 ].…”