Study of structural, elastic, optical, dielectric, and magnetic properties of sol-gel synthesized Li_0.2Co_0.3Zn_0.3Fe_2.2O₄ ferrite for optoelectronic and electrical applications

This work presents a detailed investigation of the structural, elastic, optical, dielectric, and magnetic properties of Li_0.2Co_0.3Zn_0.3Fe_2.2O₄ ferrite synthesized through the sol-gel process. The experimental structural parameters closely match the theoretical values, confirming the proposed cation distribution of the prepared sample. The FTIR spectrum and ultrasonic pulse transmission method analysis showed that the sample has brittle mechanical properties. According to UV-Vis optical absorbance analyses and based on Tauc's law, the sample exhibits a direct optical transition, with the band gap energy (E_g) determined to be 2.51 eV. The study of electrical conductivity showed that the sample exhibited a reduced activation energy (E_a= 0.154 eV) and remarkable electrical resistivity at room temperature (ρ_dc ∼ 10⁴ Ω.m), indicating the material's potential for microwave device applications. The conduction process of the sample aligns with the NSPT model. Additionally, the temperature coefficient of resistance (TCR) suggests that the sample is a promising candidate for infrared radiation detection. A low coercive field was also derived from the hysteresis loop, confirming the soft nature of the sample operating within a microwave frequency range of 8–9 GHz. Our results show that the Li_0.2Co_0.3Zn_0.3Fe_2.2O₄ compound offers advantages over the undoped Li_0.5Fe_2.5O₄ compound, including a lower band gap, reduced activation energy, and higher electrical resistivity. This suggests that substituting Co and Zn into Li_0.5Fe_2.5O₄ ferrites improves their performance in electrical and optoelectronic applications.