Mössbauer spectroscopy study of the high energy ball milling (HEBM) synthesis & kinetics of CoFe2O4 from Co(OH) 2 and α-Fe2O3

Abstract

Room temperature mechanochemical synthesis of single phase nanosized particles of CoFe2O4 by HEBM of stoichiometric mixtures of Co(OH)2 and α-Fe2O3 under wet acetone was achieved after 25 hours of continuous ball milling. The particle size and lattice constant were 98.13 nm, and 8.398 after 10 hours, while 31.96 nm and 8.343 after 25 hours. The coercivity (25 hours state) was 12.78 mT with saturation and remanent magnetizations of 27.52 Am2/kg and 3.94 Am2/kg respectively due to small amount of a magnetic phase. Mössbauer spectroscopy measurements showed very limited reaction in 5 hours, with the single phase forming directly to superparamagnetic particles. The quadrupole splitting of the doublets was in the range of 0.24-1.14 mm/s, with corresponding isomer shift range of 0.80 -0.67 mm/s. The DSC measurements of the single phase material showed that it was metastable with characteristic stages whose activation energies were determined by the modified Kissinger kinetic analyses to be in the range of 3.51 kJ/mol to 11.89 kJ/mol. © 2010 IOP Publishing Ltd.