X-ray diffraction-based characterization of magnetite nanoparticles in presence of goethite and correlation with magnetic properties

Nanoparticles synthesized using co-precipitation technique from iron salt solutions at different pH and temperatures are found to consist of magnetite, magnetite–goethite mixtures and goethite particles depending on process conditions. The synthesized particles are characterized using X-ray diffraction (XRD) technique and their magnetic properties are evaluated using a vibrating sample magnetometer (VSM). As properties of these nanoparticles are essentially dependent on various phases present, a detailed phase analysis and quantification of the magnetite phase in magnetite–goethite mixed system has been carried out using XRD technique. For quantification, a calibration graph has been made using samples of magnetite and goethite mixed in different weight percentages. Using this calibration graph, magnetite weight percentages have been estimated in mixed particles produced by co-precipitation from iron salt solutions at various pH values. A good correlation between saturation magnetization values and magnetite weight percentage has been observed in these mixed particles. When the synthesized particles are pure magnetite, the saturation magnetization value is found to depend on the diameter of the particles, estimated using XRD and VSM data.