The discovery of Giant Magneto Resistance (GMR) in Co-Cu multilayers, granulate composites and alloys have led to much interest in the synthesis and studies of such materials.
Here we describe Co-Cu nano-composites, synthesized via a solution route using balanced redox reactions during heat-treatment under inert atmosphere. It is an inexpensive, versatile route using simple salts and organic complex formers that allows for preparation of porous powders, as well as of films on various substrates e.g. glass, metals and ceramics. The materials were characterized using X-ray diffraction (XRD), electron microscopy (SEM and TEM) energy dispersive X-ray spectrometry (EDX) and SQUID measurements.
Films were prepared by spin-coating, and subsequent heat-treatment to 500°C. Grazing incidence XRD showed very weak and broad peaks from fcc Co and Cu, indicating that the films consisted of small sized nano-crystallites. SEM studies of the film surface showed a smooth, dense structure.
Powders were prepared by evaporation of the solutions to form a viscous concentrate, followed by heating to 500°C. The XRD showed fcc Co and Cu, with no evidence for alloy formation. Electron microscopy studies showed a highly porous microstructure with a wide range of pore sizes.
The composite was composed of ca 20 nm Cu particles and 3-6 nm Co particles. Magnetic measurements indicate a decrease in transition temperature and magnetic saturation with increasing amount of Cu particles.
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