Structure and Magnetic Properties of (Ni_1 – xZn_x)Fe₂O₄ Ceramics with a Spatial Change in the Composition

Abstract

Samples of homogeneous (x = 0, 0.1, and 0.2) and multilayer ceramics based on solid solutions of nickel–zinc ferrites (Ni_1 – xZn_x)Fe₂O₄ with a “contrary” composition gradient (x = 0.2 → 0 → 0.2) have been prepared by the thick-film technology. The use of the two-step sintering mode enables the ceramics synthesis and the conservation of the regular–inhomogeneous distribution of chemical elements over the thickness of the gradient samples. The microstructures and the crystal structures of the materials have been studied. The unit cell volume is shown to increase with the zinc content and, in this case, the grain size is changed only slightly. The features of the magnetization of the multilayer structures are studied for two variants of applying an external magnetic field: parallel and perpendicular to the sample plane. The resulting hysteresis loop of the multilayer gradient sample can be obtained by the “summation” of the loops of homogeneous layers of the structure. No internal fields leading to the shift and the distortion of magnetic hysteresis loops have been observed.