Multi-model XRD peak profile analysis of magnetite nanoparticles synthesized from placer magnetite ore

A multi-model X-ray diffraction (XRD) peak profile approach was applied to characterize the crystallographic and microstructural properties of magnetite nanoparticles (MNPs) synthesized from placer magnetite mineral ore as an alternative to synthetic precursors. For this purpose, eight analytical models, e.g., Scherrer-based methods, Williamson-Hall variants (UDM, USDM, UDEDM), the size-strain plot, and the Halder-Wagner method, were employed. The MNPs exhibit a single-phase cubic spinel structure with a lattice parameter of 8.33 Å and a unit cell volume of 577 Å 3 . The comparative study revealed significant variations in crystallite size, lattice strain, and residual stress depending on the analytical model. The crystallite size of MNPs ranged from 17 nm to 49 nm (average of 32 nm), with lattice strains of 1.30–4.9 × 10 −3 and residual stresses of 251–289 MPa. All estimated crystallite sizes were smaller than the FESEM derived particle size of 25–64 nm (average 42 nm), validating the multi model peak profiling for this material system. Further, FTIR spectra confirmed the prominent Fe-O stretching vibration bands, verifying the inverse spinel phase of the MNPs. The findings suggest a framework for interpreting model dependent variations in XRD derived microstructural parameters for future MNPs characterization.