Precipitation of zinc ferrite nanoparticles in the Fe 2O 3–ZnO–SiO 2 glass system

Abstract

Glass materials in the ZnO–Fe 2O 3–SiO 2 system, containing zinc ferrite nanoparticles, were prepared by the sol–gel method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, AC- and DC-magnetization techniques. The gel samples, dried at 130 °C, were further heat treated in air at 500 and 800 °C. At 500 °C zinc ferrite and hematite nanoparticles, with an average size of approximately 24 nm, were precipitated in the brown and opaque 10ZnO–10Fe 2O 3–80SiO 2 and in the ruby colored transparent 5ZnO–5Fe 2O 3–90SiO 2 and 2.5ZnO–2.5Fe 2O 3–95SiO 2 glass matrices. In the 5ZnO–5Fe 2O 3–90SiO 2 sample the nanoparticles exhibited ferro or ferrimagnetic interactions combined with superparamagnetism with a blocking temperature of approximately 14 K. Heating at 800 °C seems to cause partial dissolution of the zinc ferrite and hematite particles in all the investigated compositions. Accordingly at 800 °C the 5ZnO–5Fe 2O 3–90SiO 2 glass shows a paramagnetic behavior down to 2 K.