Structural, Optical and Dielectric Properties of Holmium-Doped Nickel-Cadmium Ferrite Nanoparticles Synthesized by Sol-Gel Auto-Combustion Method

Nanoparticles where holmium was substituted with nickel-cadmium Ni0.5Cd0.5HoxFe2-xO4 (X = 0, 0.02, and 0.04) ferrites were synthesized through a sol-gel auto-combustion process to reveal their structural and physical properties. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), a scanning electron microscope (SEM), Fourier transform infrared ray (FTIR) spectroscopy, and impedance spectroscopy techniques. XRD revealed the formation of the cubic crystal structure had a preferential orientation along (311). By including holmium, the lattice constant was reduced, while the average crystallite size was increased. SEM analysis revealed that the nanoparticles exhibited regular shapes, and the average grain size increased with the holmium content. FTIR spectroscopy determined that all the organic and inorganic materials had an absorption range of 400 to 4000 cm−1. The dielectric properties were measured between the frequency ranges of 1 kHz and 2 MHz. This shows that the tangent loss and the dielectric constant were raised when the concentration of holmium was increased.