Synthesis of Nickel Ferrite Doped with Cr3+ Ions

Abstract

   Nickel ferrite is widely used in memory devices, computer, and satellite technologies because of its unique combination of a high magnetic susceptibility, semiconductor properties, chemical stability, and mechanical hardness. The NiFe₂O₄ compound is a solid solution that allows the introduction of various metal ions, thereby affecting the magnetic, mechanical, and dielectric properties of this material. Nanocrystalline powders of nickel ferrite doped with Cr³⁺ ions with a degree of substitution x = 0.1–1.5 have been obtained by autocombustion. According to the X-ray diffraction analysis, the prepared substances have the structure of nickel ferrite. When they are doped, a solid substitution is formed, accompanied by a decrease in the parameters of the cubic lattice and interplane distances. The morphology and size of the undoped nickel ferrite particles significantly differ from the chromium substituted samples. The scanning electron microscopy data have shown that the average particle size of doped nickel ferrite is about 40 nm, while as the calcination temperature increases, particles agglomerate and, as a consequence, increase in size. It has been found that chromium ion doping reduces the phase formation temperature of nickel ferrite.