In this study, calcium-doped manganese nano ferrites of composition Ca x Mn 1−x Fe 2 O 4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) were synthesized using a flexible, high-purity, and environmentally friendly hydrothermal method. The cubic single-phase spinel structure was verified by X-ray diffraction (XRD) analysis. The crystallite size was observed to be in the range between 22.8 and 32.7 nm and the lattice strain decreased from 1.1 × 10 − 3 to 2.0 × 10 − 3 with an increase in calcium concentration. Potential stretching analysis was employed to extract the functional groups using Fourier transform infrared spectroscopy (FTIR), which revealed the presence of frequency bands corresponding to the tetrahedral and octahedral sites in all samples. An “S”-shaped curve in the Vibrating Sample Magnetometer (VSM) analysis illustrates the low coercivity values for every sample in the 1.10–2.37 kOe range. The obtained impedance spectra showed the contribution of grain boundary for x = 0.4 and 1.0, whereas the contribution of grains for other compositions. Additionally, the electrochemical behaviour of the samples was examined by cyclic voltammetry (CV), which predicted an excellent specific capacitance stability of all the samples over 10 cycles at each scan rate. The optimal Ca₀.₄Mn₀.₆Fe₂O₄ composition exhibited a specific capacitance of 0.143 F/g at 25 mV/s and coercivity of 0.63 kOe. The synthesized material can be used in radio frequency applications, sensors, and transformers.
Nancy et al. (2026) studied this question.