Energetic and magnetic directional aggregation properties of KPA@Fe₃O₄composite particles prepared via a microcrystalline co-precipitation route

The development of new electromagnetic interference materials has attracted much attention in the information warfare. Herein, a novel KPA@Fe3O4 composite particle was synthesized via a microcrystalline co-precipitation method. X-ray diffractions, scanning electron microscopes and vibrating sample magnetometer measurements were used to characterize the products. The results indicated that the surface of the potassium picrate (KPA) crystals was covered by magnetic Fe3O4 nanoparticles, and composite particles exhibited excellent magnetic properties. Furthermore, the thermal behavior of the composite particles was investigated by differential scanning calorimetry, which showed that the composite particles inherited the energetic property of pure KPA crystals when the mass fraction of magnetic component was 50%, or 65%. As for the composite particles with 75% magnetic component, the thermal stability of was poor. In addition, the magnetic directional aggregation performance of composite particles was analyzed by dynamic simulation, which moved toward the magnetic source. For the composite particles with 50% magnetic component, the maximum concentration was about 63 times of the initial concentration, and the peak velocity was 0.63 m s-1. With the mass fraction of magnetic component increasing to 65%, the concentration and velocity of the composite particles generally increased at the corresponding moment. As the mass fraction of magnetic component increased to 75%, the change of them was not obvious. Therefore, the composite particles with F3O4/KPA mass ratios of 65/35 had the best comprehensive properties. The excellent energetic and magnetic directional aggregation properties can allow the composites to be used in many potential applications in the information warfare.