Effect of Fe/Co Double-Loaded ZnO Nanopowder on Magnetic and Dielectric Properties for Energy Storage and Spintronic Devices

This study uses the sol-gel process (SGP) to produce cobalt (Co) and iron (Fe) double-loaded zinc oxide (ZnO) nanostructures. The percentages of Co ions considered in this work are 0.2, 1, 3, 4, and 7 mol%, and the percentage of Fe ions is still unchanged at 5 mol%. We evaluated the specimens to determine their structural, dielectric, and magnetic behaviors. The X-ray diffraction (XRD) illustrations proved that the crystallite sizes got bigger as the Co concentration levels rose. The XRD result also confirmed the hexagonal (wurtzite) crystal nanostructure of ZnO and the effective incorporation of Co²⁺ and Fe²⁺ ions into the lattice coordinates of Zn²⁺ ions. X-ray photoelectron (XPS) spectroscopy was presented to examine the chemical composition of the samples. Photoluminescence analysis (PL) indicated that the incorporated ions generate characteristic emission bands and structural defects in the prepared nanopowder. The HR-TEM photographs demonstrate that the particle sizes vary, with the average being between 44 and 54 nm. The Maxwell-Wagner Model has helped us fully understand how the dielectric loss (tan δ), the ac conductivity (σ_ac), and the real and imaginary permittivity constants (ε’, ε’’) change with frequency and cobalt concentrations. The dielectric investigation indicated that both dielectric constant and electrical conductivity enhance with the loading of Cobalt ions into ZnO nanostructure. All the double-loaded specimens exhibit room-temperature ferromagnetism (RTFM). The increase in oxygen vacancies causing the formation of bound magnetic polarons explains this phenomenon. It is recommended that Fe/Co double-loaded ZnO be used in spin-based electronics and high-frequency storage devices.