This study investigated the production of Cu²⁺-doped CoFe₂O₄ nanoparticles (CFO NPs) using a facile sol−gel technique. The impact of Cu²⁺ doping on the lattice parameters, morphology, optical properties, and electrical properties of CFO NPs was investigated for applications in electrical devices. The XRD analysis revealed the formation of spinel-phased crystalline structures of the specimens with no impurity phases. The average grain size, lattice constant, cell volume, and porosity were measured in the range of 4.55–7.07 nm, 8.1770–8.1097 Å, 546.7414–533.3525 ų, and 8.77–6.93%, respectively. The SEM analysis revealed a change in morphology of the specimens with a rise in Cu²⁺ content. The particles started gaining a defined shape and size with a rise in Cu²⁺ doping. The Cu_0.12Co_0.88Fe₂O₄ NPs revealed clear grain boundaries with the least agglomeration. The energy band gap declined from 3.98 eV to 3.21 eV with a shift in Cu²⁺ concentration from 0.4 to 0.12. The electrical studies showed that doping a trace amount of Cu²⁺ improved the electrical properties of the CFO NPs without producing any structural distortions. The conductivity of the Cu²⁺-doped CFO NPs increased from 6.66 × 10⁻¹⁰ to 5.26 × 10⁻⁶ ℧ cm⁻¹ with a rise in Cu²⁺ concentration. The improved structural and electrical characteristics of the prepared Cu²⁺-doped CFO NPs made them a suitable candidate for electrical devices, diodes, and sensor technology applications.

Spinel ferrites are widely investigated for their widespread applications in high-frequency and energy storage devices. This work focuses on enhancing the magnetic and dielectric properties of Ni_0.25Cu_0.25Zn_0.50 ferrite series through non-thermal microwave plasma exposure under low-pressure conditions. A series of Ni_0.25Cu_0.25Zn_0.50 ferrites was produced using a facile sol–gel auto-ignition approach. The post-synthesis plasma treatment was given in a low-pressure chamber by sustaining oxygen plasma with a microwave source. The structural formation of control and plasma-modified ferrites was investigated through X-ray diffraction analysis, which confirmed the formation of the fcc cubical structure of all samples. The plasma treatment did not affect crystallize size but significantly altered the surface porosity. The surface porosity increased after plasma treatment and average crystallite size was measured as about ~49.13 nm. Morphological studies confirmed changes in surface morphology and reduction in particle size on plasma exposure. The saturation magnetization of plasma-exposed ferrites was roughly 65% higher than the control. The saturation magnetization, remnant magnetization, and coercivity of plasma-exposed ferrites were calculated as 74.46 emu/g, 26.35 emu/g, and 1040 Oe, respectively. Dielectric characteristics revealed a better response of plasma-exposed ferrites to electromagnetic waves than control. These findings suggest that the plasma-exposed ferrites are good candidates for constructing high-frequency devices.

This research work employs a sol–gel process to prepare Ni _{1− x} Ce _x Fe ₂ O ₄ ( x = 0.00, 0.05, and 0.10) samples.

This study produced nanofluids via a two-step method by dispersing copper–nickel–zinc (CuNiZnFe2O4) ferrite nanocomposites in transformer and kerosene oils. A sol–gel auto-combustion approach was adopted to synthesize ferrite nanoparticles. The prepared nanoparticles were analyzed through scanning electron microscopy, photoluminescence spectroscopy, and x-ray diffraction. The measured crystallite size varied between 11 and 13 nm. The SEM images show that the structures of the developed CuNiZn nanoparticles are irregular. The photoluminescence results give a bandgap of 1.91 eV and the emission lines of the nanoparticles. Transient hot wire analysis was performed to determine the thermal conductivity of the base fluid and the prepared nanofluids. It is observed that nanoparticles in the nanofluid enhance the heat transfer rate. It has been proven that CuNiZn/kerosene-based nanofluids have greater thermal conductivity than CuNiZn/transformer oil-based nanofluids. The viscosity of transformer oil-based nanofluids at room temperature is 12.53 mm2 s−1, which decreases to 12.49 mm2 s−1 at 40 °C. Similarly, the viscosity of kerosene-based nanofluids is 1.49 mm2 s−1 at room temperature and 1.16 mm2 s−1 at 40 °C. The sedimentation method revealed that CuNiZn/transformer oil-based nanofluids have greater stability than CuNiZn/kerosene-based nanofluids.

In this study, a sol–gel auto-combustion technique was adopted to synthesize La ³⁺ -substituted CoFe ₂ O ₄ ( x = 0.00, 0.05, and 0.10) nanoparticles for use in electronic device applications by modifying the dielectric loss control of CFO nanoparticles.