Enhanced Magneto-Electric Properties of ZnAl2O4@NiFe2O4 Nanocomposites in Magnetic Sensor Applications

Ferrimagnetic substance-based Zn0.4Alx@Ni0.6-xFe2O4 (x = 0.0, 0.02, 0.04, 0.06, and 0.08) nanocomposite system was prepared by two-step seed implant polyacrylamide sol–gel method. The structural and frequency-dependent sensitivity of soft magnetic core materials was optimized by the substitution of Al3+ ions. The nonstoichiometric of the constituents has caused by the consisting of a small amount of two secondary phases (Zn-oxide and Zn-Al-oxide) which have been detected from the short intensity of XRD peaks using the Rietveld refinement program. The replacement of Ni2+ ions by Al3+ ions plays a major role in the rearrangements of Ni2+ and Fe3+ ions between octahedral A and tetrahedral B sites and is lead to optimization of magnetic behavior and impedance response. The maximum coercivity (493.73 Oe) and saturation magnetization (58.26 emu/g) observed at x = 0.08 and 0.02, respectively. The resulting magnetic permeability shows that the value is enhanced up to 6.411% within 1 Oe of applied magnetic field. In addition, the impedance value reaches maximum of 1.49 × 105 Ω at sample x = 0.02, reduced to minimum of 4.8 × 103 Ω at x = 0.08. The magnetic sensitivity of ZnAl-NiFe2O4-based core materials at room temperature under 0–5 log f with 0.01 T magnetic field has also been investigated. The magneto-impedance results can be used to substantiate the increase in sensitivity due to the rearrangement of Ni2+ and Fe3+ ions.