Comparative study of crystallite size and microstructural parameters of Fe ₃ O ₄ and CoFe ₂ O ₄ nanoparticles synthesized via sol–gel auto combustion method

This study investigates the structural and microstructural characteristics of magnetite (Fe₃O₄) and cobalt ferrite (CoFe₂O₄) nanoparticles synthesized via the sol-gel auto-combustion method using ferric nitrate and cobalt nitrate as metal precursors. X-ray diffraction (XRD) analysis confirmed the formation of single-phase crystalline nanoparticles with a cubic inverse spinel structure. Transmission electron microscopy further validated the nanocrystalline nature and morphological uniformity of the particles. To gain deeper insight into the crystallite size and lattice strain, multiple XRD-based analytical approaches Williamson-Hall, size-strain plot, and Halder-Wagner methods were employed. The novelty of this work lies in the first systematic side-by-side comparison of Fe₃O₄and CoFe₂O₄nanoparticles synthesized under identical conditions and evaluated using four complementary XRD models, ensuring cross-validated accuracy. The comparative evaluation of these models revealed slight discrepancies in size estimations, attributed to their varied assumptions regarding strain and instrumental broadening. Notably, CoFe₂O₄nanoparticles exhibited marginally larger crystallite sizes and higher lattice strain compared to Fe₃O₄, imply compositional influence on structural properties. The combined application of these analytical techniques enabled accurate estimation of crystallite size, microstrain, and energy density, providing insights into the mechanical stability and potential functional behavior of the synthesized nanoparticles.