An easy and cost-effective route is demonstrated to grow spongy-network-like polyaniline (SpN-PANI) thin films on stainless steel (SS) by galvanostatic electrodeposition. Through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) characterizations, the physicochemical properties of the SpN-PANI thin films were fine-tuned for supercapacitor application. The hydrophilic nature of SpN-PANI thin films was examined by using contact angle measurements. Next, the capacitive behavior of the SpN-PANI thin film was assessed by using cyclic voltammetry (CV), galvanostatic charging-discharging (GCD), and electrochemical impedance spectroscopy (EIS). Specifically, these results show that SpN-PANI thin films can exhibit a maximum specific capacitance of 580 F.g⁻¹ at a scan rate of 5 mV.s⁻¹ in a 0.5 M Na₂SO₄ electrolyte solution, as well as superior cycling stability (84% capacity retention after 1000 cycles). Thus, the strategy presented here can be applicable to produce a SpN-PANI-based thin film which has prospects as an active electrode material for supercapacitor devices.

The highly desirable properties of lithium ferrite and various metal ion substituted lithium ferrite make it a useful material for many electronic and magnetic applications. This research used a simple sol-gel auto-combustion method for the synthesis of Cr substituted Li _0.5 Fe _2.5 O ₄ ferrite. Here, in the B-site, Fe ³⁺ ions were swapped by non-magnetic Cr ³⁺ ions at different concentrations. All the samples of Cr substituted Li _0.5 Fe _2.5 O ₄ were confirmed through X-ray diffraction patterns to have a single-phase spinel-type structure with cubic symmetry, which was thereafter confirmed by its refinement through Rietveld. An increase in the substitution of Cr ³⁺ instead of Fe ³⁺ ions in the spinel ferrite system results in an increased nanocrystalline size. The average crystallite size decreased from 30 nm to 10 nm with an increase in Cr ³⁺ content. Analogous particle size was evaluated through transmission electron microscopy (TEM) analysis. Fourier transform infrared spectroscopy (FTIR) provides an overview of the structural distortion of the lithium ferrite lattice with the substitution of Cr ³⁺ ions. The Semiconducting (NTCR) nature of the Cr substituted Li _0.5 Fe _2.5 O ₄ nanoparticles was confirmed through the temperature-dependent DC resistivity. The evaluated trend of the dielectric properties ( ε ′, ε ″, and tan δ ) strengthens the facts observed in the electrical conduction mechanism.