Novel iron oxide–silica coreshell powders compacted by using pulsed electric currentsintering: Optical and magnetic properties

Abstract

The properties of the bulk materials consolidated of silica coreshell powders with iron oxide core have been studied. Iron oxide nanoparticles smallerthan 20nmin sizewere synthesized by a reverse co-precipitation processin ambient atmosphere.Coreshellstructureswith various amounts of iron oxide were prepared via a modified Stöber method. The powders were compacted by using pulsed electric current sintering (PECS) at 1373K. The morphologies, microstructures, phases, optical, and magnetic properties of the samples were studied by using transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), UV–visible spectroscopy (UV–Vis), and vibrating sample magnetometer (VSM). Transmittance valuesin the 250–800nm range varied with the amount of iron oxide. Sample with the lower content was transparent while the sample with the highest content was opaque withmicroporosity.The compact with the highest iron oxide contentshowed the ferromagnetic behaviour at 300K. The phase transformationsin the coreshell powders during the sintering process are discussed.