Structure Analysis and Magnetic Properties of Nano-Sized Lithium-Copper Ferrite Particles Classified by Using Ultrasonic Floating-Sedimentation Method

Abstract

Ultrasonic floating-sedimentation (UFS) method was applied to classify nano-sized lithium-copper ferrite particles with about 30 nm in size. The nano-sized ferrite particles were prepared by self-propagating high temperature synthesis (SHS) reaction with different initial composition ratio of lithium peroxide to copper oxide followed by mechanical milling, which combustion temperature and combustion rate at 1.0 MP of oxygen pressure were in the ranges of 870 degrees C to 930 degrees C and 4.2 to 5.5 mm sec(-1), respectively. Neutron diffraction analysis revealed that the final products of the SHS reaction with initial molar ratios of lithium peroxide to copper oxide of 0.5 and 1.0 were mainly Li0.29Cuo.61Fe,2O4 and Li0.42Cu0.58Fe2O4 with Fd3m structure, which lattice parameters were 0.8340 nm and 0.8332 nm, respectively. As the molar ratio of lithium peroxide to copper oxide increased from 0.5 to 1.0, the maximum magnetization (Ms), residual magnetization (Mr) and coercive force (iHc) were increased about 35%, 18% and 17%, respectively, which were related to non-stoichiometry of the ferrites. Complex permeability of the ferrite-rubber composites specimen decreased with the increase of frequency with peak real value of at about 0.8 GHz, and their dielectric constant were epsilon'r = 10.9 and epsilon'r" = 0.2, respectively.