LITHIUM FERRITE NANOCRYSTALS EMBEDDED IN A NONMAGNETIC GLASS MATRIX

Nanocrystalline LiFe5O8 particles embedded in an amorphous matrix were obtained by heal treatments of the nonmagnetic oxide glass 32Li(2)O-8 FeO(3)-60B(2)O(3), between 200 and 770 degrees C. The X-ray spectra re veal the formation of the spinel phase of Li-ferrite in the initially amorphous materials only for annealing temperatures higher than 440 de grees C and the hybrid structure becomes more evident with the increas e 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 compou nds in terms of annealing temperature was investigated. The magnetic p roperties (sigma(s), H-c) are correlated with the average size of the LiFe5O8 nanoparticles dispersed in the glass matrix. The X-ray diffrac tion data indicated an evident increase in the average crystal block s ize from 3.5 to 50 nm with the increase of annealing temperature from 440 degrees to 770 degrees C.