Lithium ferrite nanocrystals embedded in a non-magnetic glass matrix

Nanocrystalline LiFe5O8 particles embedded in an amorphous matrix were obtained by heal treatments of the nonmagnetic oxide glass 32Li(2)O-8FeO(3)-60B(2)O(3), between 200 and 770 degrees C. The X-ray spectra reveal the formation of the spinel phase of Li-ferrite in the initially amorphous materials only for annealing temperatures higher than 440 degrees C and the hybrid structure becomes more evident with the increase of temperature. The occurrence of the magnetic spinel phase (LiFe5O8) was proved by magnetization and Curie temperature measurements too. The evolution of the magnetic properties of these glass-ceramic compounds in terms of annealing temperature was investigated. The magnetic properties (sigma(s), H-c) are correlated with the average size of the LiFe5O8 nanoparticles dispersed in the glass matrix. The X-ray diffraction data indicated an evident increase in the average crystal block size from 3.5 to 50 nm with the increase of annealing temperature from 440 degrees to 770 degrees C.