Magnetic properties of (Co, Al) co-doped SnO2 nanoparticles

The desired size of pure SnO2 and Co (1, 3, 5 mol%) with constant 5 mol% of Al co-doped into SnO2 nanoparticles are synthesized by chemical co-precipitation method. The raw materials used in synthesis are SnCl2.2H2O, AlCl3, Co (C2H3O2).4H2O, aqueous NH4OH and Polyethyleneglycol (PEG) from AR grade. The XRD pattern of pure and co-doped samples confirm the formation of tetragonal rutile phase of SnO2 nanoparticles with average particle size 25 and 20 nm respectively. Micrographs of scanning electron microscope (SEM) for pure and (Co, Al) co-doped into SnO2 show that the prepared nanoparticles are agglomerate and spherical in shape. The EDAX spectra of prepared nanoparticles indicate the presence of Co2+, Al3+, Sn4+ and O2+ and also confirm stoichiometric proportions of raw material in the formation of SnO2. Transmission electron microscope (TEM) reveals that the surface morphology of pure and co-doped samples are spherical, and average size of particles is ~20 nm. Magnetization measurements from M-H curves of VSM show that the ferromagnetism at low concentration of Co and at higher concentration of Co shows weak ferromagnetism due to super exchange coupling among neighboring ions. The bound magnetic polarons model supports the observed ferromagnetic behavior.