Magnetostrictive properties of nanocrystalline Co–Ni ferrites

Nanocrystalline Co–Ni samples were prepared using the co-precipitation technique. X-ray diffraction technique was used to check the phase purity of the samples. Surface morphology was studied using atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques. Nanosized grains of the samples were seen in AFM images of ultrasonicated powders. The nanocrystalline powders were shaped into pellets of desired size and used to record magnetostriction in the samples. The strain gauge method was used to record magnetostriction as a function of magnetic field in the range 0–10 kOe. The parallel and perpendicular magnetostrictions are of opposite signs. Maximum value of magnetostriction varies systematically with change in Co–Ni content. Magnetic hystersis (M–H) curves were recorded using the VSM technique.