Magnetic and magnetostrictive properties of Cu-doped cobalt ferrite

•Single phase cubic-spinel structure is formed by a facile auto-combustion method.•CCFO shows the tailored magnetostriction by variant ratio of Cu/Co, with a large saturation magnetostriction λS ∼ 240 ppm.•An enhanced low-field magnetostriction (λa ∼ 150 ppm@2 kOe) and a low magnetocrystalline anisotropy (K1 ∼ 3.7 × 106 erg/cm3) are obtained.•A high piezomagnetic coefficient (d33 ∼ 1.44 nm/A at 1.5 kOe) is achieved. The Cu-doped cobalt ferrites CuxCo1-xFe2O4 (CCFO) were synthesized by a glycine-nitrate sol-gel auto-combustion method and investigated for structural, magnetic and magnetostrictive properties. X-ray diffraction and scanning electron microscopy analysis revealed the formation of single cubic-spinel phase for all the as-prepared powders, followed by the sintered samples with grain sizes around 2.5 µm. The variation in stoichiometric composition can be used to tailor magnetic and magnetostrictive properties. Saturation magnetization MS decreases from 84.8 to 60.4 emu/g with increasing Cu content from x = 0.0 to x = 0.50, accompanied with a reduction in coercivity HC from 1.21 to 0.41 kOe. The introduction Cu into CFO is conductive to the decline in magnetocrystalline anisotropy, giving rise to an improvement in magnetostriction at low applied fields. An optimized composition in the CuxCo1-xFe2O4 ferrites is found to be around x = 0.30, achieving good magnetoelastic properties, i.e., a large saturation magnetostriction (–λS ∼ 240 ppm), a high strain sensitivity (–dλ/dH ∼ 1.44 nm/A), as well as a low magnetocrystalline anisotropy coefficient (K1 ∼ 3.7 × 106 erg/cm3). The excellent magnetoelastic properties and the combination in a facile synthesis process for sintered polycrystalline ferrites, suggest promising prospects in magnetostriction applications.