Preparation of strontium hexaferrite based materials by solution combustion: the effect of charges arising in precursors and an external magnetic field

Abstract

The formation of electric charges during the synthesis of complex oxide materials based on strontium hexaferrite SrFe12O19, including doped with lanthanum and cobalt ions, via the combustion of nitrate-organic precursors has been established. Precursors included polyvinyl alcohol or glycine as organic component. The intensity of charge generation was lower for precursors containing a larger amount of organic component. Data on the magnetic characteristics of the samples were obtained: magnetization, coercive force. The influence of an external magnetic field during the synthesis of hexaferrites significantly affected the coercive force of the samples and allowed to increase its values due to the formation of extended ensembles of nanoparticles. At the same time, such an effect on samples with a relatively low level of charge generation during precursor combustion was more effective. The relationship between the factors influencing the formation of extended aggregates is analyzed. The Sr0.8La0.2Fe11.8Co0.2O19 samples had the maximum coercive force. One of the techniques for increasing the coercive force is a two-stage thermomagnetic treatment, including a low-temperature stage. The formation of branched extended structures at the macro- and micro-levels was found during the combustion of glycine-containing precursors.