Influence of Fe/Ba molar ratio on the characteristics of Ba-hexaferrite particles prepared by sol-gel combustion method

Nano-crystalline particles of barium hexaferrite (BaFe12O19) have been prepared by a sol-gel combustion technique using nitrate-citrate gels prepared from metal nitrates and citric acid solutions under various Fe/Ba molar ratios of 10, 11 and 12. The thermal decomposition process of the nitrate-citrate gels and as-burnt powders was investigated by XRD and DTA/TGA techniques. The results revealed that the nitrate citrate gels exhibit a self-propagating behavior after ignition and the single-phase barium hexaferrite formation temperature is significantly influenced by Fe/Ba molar ratio. The Fe/Ba molar ratio of 11 is more favorable for formation of barium hexaferrite. The SEM investigations revealed that the mean particle size of barium hexaferrite dramatically increases with increasing calcination temperature from 1000 to 1100 °C. The magnetic properties measured using a vibrating sample magnetometer (VSM) revealed that the sample synthesized under Fe/Ba molar ratio of 11, exhibits higher saturation magnetization in comparison with those synthesized under Fe/Ba molar ratios of 10 and 12.