Hydrothermal Temperature Influence On Magnetic And Fmr Properties Of Hematite Nanoparticles

Investigation of the role of hydrothermal temperature on hematite nanoparticles structural, magnetic, and ferromagnetic resonance (FMR) properties was done. Ferric chloride and sodium hydroxide were used as the starting precursors. The hydrothermal temperature was varied in the range of 140–200∘C by a step of 20∘C. XRD, SEM, VSM, and FMR analyses were used to check the particles’ properties. The prevailing strongly phase was hematite with some small peaks related to other phases. A reduction in lattice constant and increase in the crystallite size to more than 27nm is observed. The particles’ morphology exhibited polygon particles down to spherical particles as the average particle size gets larger up to 45nm. The hysteresis loops showed unsaturated curves with rising coercivity up to 150Oe. The antiferromagnetism permeability, magnetization saturation, and dipole moment were found by Langevin fitting to the experimental hysteresis loops, where all of them have the same behavior represented by an initial drop followed by increase in their values. The FMR spectra are characterized by low intensities and low linewidths accompanied by very low blue shift in the resonance field. All samples showed Lorentzian distribution as checked by the Lorentz function. Landé g-factor has values very close but less than 2 due to the effect of crystal field and particle magnetic moment variations.