The effect of transition metal substitution on the structural, elastic, optical, electrical and dielectric properties of M0.5Fe2.5O4 (M=Co and Mg) synthesized by the auto combustion method

Spinel nanoparticles M0.5Fe2.5O4 (M = Co,Mg) were elaborated by the auto-combustion method using glycine as a fuel. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy have been invested to investigate the structural and morphological properties of these compounds. The optical study reveals that these samples exhibit a strong absorption in the visible range. They possess intermediate gap energies 2.91 eV for Co0.5Fe2.5O4 and 3.16 eV for Mg0.5Fe2.5O4 which makes them good candidates in terms of photovoltaic applications. Electrical analysis demonstrates a semiconductor [300-520 K] -metallic [540-660 K] transition at 540 K. Correlated Barrier Hopping (CBH) and No Overlap Small Polaron Tunneling (NSPT) models dominate the conduction mechanisms in both compounds. The Nyquist diagrams are modelled by two series-connected circuits reflecting grain (Rg//Cg) and grain boundary effects (Rgb//CPEgb). Quantitative analysis of the dielectric constant is indicative that these compounds are promising at the level of electronic systems industry, LTCC devices and super capacitor applications.

Automated summary

Spinel nanoparticles M0.5Fe2.5O4 (M = Co, Mg) were synthesized by the auto-combustion method using glycine as a fuel. The structural and morphological properties of these compounds were investigated using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The optical study showed strong absorption in the visible range and intermediate gap energies (2.91 eV for Co0.5Fe2.5O4, 3.16 eV for Mg0.5Fe2.5O4), making them promising candidates for photovoltaic applications. The electrical analysis revealed a semiconductor-metallic transition at 540 K and the conduction mechanisms were dominated by Correlated Barrier Hopping (CBH) and No Overlap Small Polaron Tunneling (NSPT) models. The dielectric constant analysis indicated potential applications in the electronic systems industry, LTCC devices, and super capacitor applications.