Sucrose as a sol-gel synthesis additive for tuning spinel inversion and improving the magnetic properties of CoFe2O4 nanoparticles

Abstract

Cobalt ferrite (CoFe2O4) nanoparticles were synthesized via the sol-gel method using varying quantities of sucrose as fuel. Thermal analysis shows the strong influence of the presence of the additive on the autoignition of systems. X-ray diffractograms indicate the successful formation of pure CoFe2O4 in all studied samples. As the sucrose concentration increased, crystallite sizes also increased, as shown via TEM, XRD and adsorption assays. TEM images also demonstrate the spherical tendency of the produced ferrites. Raman spectra show an increased tendency towards a normal configuration along increases in sucrose concentration. A redshift in the vibrational modes further indicates an increase in the number of vacancies in the structure, which were likely related to the reducing character of sucrose. These changes in the crystalline arrangement of the ferrites led to large variations in optical band gap energies, which increase with the addition of the carbohydrate. A maximum in coercivity of 1792 Oe was observed for the sample prepared with an initial sucrose concentration of 72 mmol L−1, which could be linked to the formation of single-domain nanoparticles. Magnetization increased with increasing sucrose additions. This phenomenon is a direct consequence of the cationic reshuffling caused by the presence of the carbohydrate.