Transparent magnetic composites of ZnFe2O4 nanoparticles in silica

Uniformly dispersed zinc ferrite nanoparticles were successfully synthesize d in a silica matrix with both the magnetic properties and optical transpar ency designed in the visible wavelength region. The phases and morphologies of these zinc ferrite particles were examined using x-ray diffraction, Ram an spectroscopy and transmission electron microscopy. A much lower formatio n temperature of ZnFe2O4 in nanocomposites was observed in this study compa red to in conventional ceramic processing. The particle size of zinc ferrit e was found to vary with the initial drying temperature, suggesting that a well-established silica network provides more confinement to the growth of ZnFe2O4 particles. The magnetic properties, measured at both 78 K and room temperature, exhibit strong dependence on the particle size, and are relate d to the unusual cation distribution and the surface effect of nanoparticle s. The optical properties of the nanocomposites can be adjusted by varying the concentration of the zinc ferrite nanoparticles. Their absorption coeff icient remains below 400 cm(-1) in the red visible light region. (C) 2001 A merican Institute of Physics.