Characterization and structural analysis of nano-sized Ba-Zn ferrite powders prepared by using a self-propagating high-temperature synthesis reaction and mechanical milling

Nano-sized Ba(x)Zn(1-x)Fe(2)O(4) ferrites were prepared by using a self-propagating high-temperature synthesis (SHS) reaction, followed by mechanical milling. The combustion temperature and the propagating rate during the SHS reaction were in the ranges of 860-1208 K and 4.9-6.0 mm/s, respectively. The final products were crystalline Ba(0.23)Zn(0.77)Fe(2)O(4) and Ba(0.48)Zn(0.52)Fe(2)O(4) phases with an average particle size of less than about 100 nm. As the initial composition ratio of BaO/ZnO and the oxygen partial pressure during the SHS reaction changed from 0.5 to 2.0 and 0.025 to 0.1, the maximum magnetization (Ms), residual magnetization (Mr) and coercive force (iHc) changed by about 233%, 372% and 82%, respectively. The complex permeability decreases with an increase of the frequency, and its real value (mu(r)') has a peak value at about 0.3 GHz. Neutron diffraction revealed that the changes of the magnetic properties and permeability were related to the non-stoichiometries of the ferrite powders. (C) 2009 Published by Elsevier B.V.