Mossbauer Spectroscopy of Thulium Oxide-Hematite Nanoparticle System

Mixed oxide nanoparticles of the type xTm₂O₃ *(1-x)α-Fe₂O₃ were synthesized by mechanochemical activation using high energy ball milling for time periods of 0-12 hours and molarities x=0.1 and 0.5. The samples were characterized by transmission Mossbauer spectroscopy using Co⁵⁷ gamma ray source and a constant acceleration spectrometer. The spectra were analyzed by least squares fitting in the assumption of Lorentzian line shapes. The 0 hour sample was fitted with a sextet having a magnetic hyperfine field of 51.9 Tesla characteristic to hematite. The milled sample spectra were deconvoluted using 2-4 sextets with decreasing values of the hyperfine magnetic field corresponding to thulium ions substituting iron in the hematite lattice. A quadrupole split doublet was added to the fits to account for thulium iron perovskite formation or the presence of superparamagnetic particles in the system. Our results support the formation of solid solutions in the milled specimens.