Synthesis of Sn(1−x)Fex@FeySn(1−y)Oz nanohybrids via a simple programmed microfluidic process

Abstract

Core–shell Sn_(1−x)Fe_x@Fe_ySn_(1−y)O_z nanohybrids are synthesized via a simple programmed microfluidic process. Characterization by high resolution transmission electron microscopy, energy dispersion X-ray spectroscopy and X-ray diffraction indicates that their sizes, shapes, compositions and crystal structures can be conveniently tuned by reaction temperatures. Different from the orientated growth to rod shaped Sn_(1−x)Fe_x@Fe_ySn_(1−y)O_z nanorods (x ≪ 0.1, y < 0.5) with tin-rich crystalline cores and amorphous shells mixing with tiny Fe@FeO_x nanoparticles at a low reaction temperature (e.g., 30 °C), the Sn_(1−x)Fe_x@Fe_ySn_(1−y)O_z nanospheres (x < 0.5, 0.5 ＜ y < 1) with crystalline tin-rich FeSn alloy cores and surface oxidized tin ferrite shells can be formed at an elevated reaction temperature (e.g., 90 °C). A blue-shift was found in the photoluminescence spectrum due to the existence of Fe in Sn_(1−x)Fe_x@Fe_ySn_(1−y)O_z nanospheres compared with those Sn@SnO₂ nanohybrids. The superparamagnetic property observed in the nanospheres can be attributed to the SnFe alloy cores and amorphous tin ferrite shells. As to the portion of Fe doping of Sn@SnO₂ nanorods mixed with Fe@FeO_x nanoparticles formed at 30 °C, they exhibit paramagnetic properties with increased saturated magnetic fields.