Mӧssbauer Spectroscopy and X-ray Powder Diffraction Study on the Milled Gallium Oxide-hematite Nanoparticles

Abstract

Samples in the milled gallium oxide-hematite nanoparticles system were synthesized by mechanochemical activation using ball milling times of 0, 2, 4, 8, and 12 hours.  The specimens were characterized using Mӧssbauer spectroscopy and X-ray powder diffraction (XRPD).  The Mӧssbauer spectra were deconvoluted by least squares fitting using 2 sextets and a doublet.  Lorentzian lineshapes were used in the assumption of thin absorbers approximation.  The sextets were assigned to hematite and gallium-doped hematite.  The relative area of doublet that represented gallium iron perovskite (gallium orthoferrite), increased with the milling time.  The hyperfine magnetic fields decreased as a function of the substitution level according to the model of local atomic environment. The particle size was determined using the Scherrer method for XRPD.  The crystallite dimensions were found to be in the tens of nanometers range.  These structural and magnetic properties of the milled gallium oxide-hematite nanoparticles system depend on the ball milling times and molar concentrations.