High concentration of hematite nanoparticles in a silica matrix: Structural and magnetic properties

摘要: Abstract The α-Fe2O3/SiO2 nanocomposite containing 45 wt% of hematite was prepared by the sol–gel method followed heating in air at 200 °C. so-obtained composite iron(III) nanoparticles dissolved glassy silica matrix investigated X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID) magnetometry. XRPD confirms formation a single-phase sample, whereas TEM reveals spherical particles with an average diameter 10 nm. DC magnetization shows bifurcation zero-field-cooled (ZFC) field-cooled (FC) branches up to room temperature blocking TB=65 K. Isothermal M(H) dependence displays significant hysteretic behaviour below TB, data were successfully fitted weighted Langevin function. particle size obtained from this fit is agreement findings. small shift TB value magnetic field strength, narrowing hysteresis loop low applied field, frequency AC susceptibility point presence inter-particle interactions. analysis results suggests that system consists single-domain intermediate strength