Synthesis and analysis of low field high magnetostrictive Ni-Co ferrite for magneto-electric energy harvesting applications

•The cobalt substituted nickel ferrites with the compositional formula Ni1-xCoxFe2O4 (x = 0.0, 0.25, 0.5, 0.75 and 1) are synthesized by sol–gel technique successfully.•The optical properties of the prepared samples are good.•The systematic change in the M−O bands with Co substitution in Nickel ferrite samples. was observed in FTIR spectra.•The prepared samples are showing good magnetic properties especially showing high. magnetostriction values at lower fields. Low field high magnetostrictive cobalt substituted nickel ferrites with composition Ni1-xCoxFe2O4 (x = 0, 0.25, 0.5, 0.75 and 1) were synthesized by sol gel technique. The formation of cubic spinel structure of samples was confirmed by X-ray diffraction. Surface morphology and optical properties were studied by using scanning electron microscopy and Differential Reflectance spectroscopy. The systematic change in the Metal-Oxygen (M−O) bands with Co substitution in nickel ferrite samples was observed in Fourier Transform Infrared spectra. With Co substitution remanance and coercivity values were increased and Curie temperature values were decreased systematically. The magnetostriction was found to increase with the substitution of Co from 10 ppm to a maximum value of about 200 ppm. Ni0.5Co0.5Fe2O4 showed magnetostriction of ∼−63 ppm at 1500 Oe and ∼−85 ppm at 2000 Oe and strain sensitivity value 1.74x10-9A-1m at 1500 Oe.