Biphasic lithium iron oxide nanocomposites for enhancement in electromagnetic interference shielding properties

There is a great demand for efficient electromagnetic interference (EMI) shielding materials due to exponential growth in wireless telecommunication devices. These devices emit electromagnetic radiation that can disrupt electronic devices, and cause health hazards. Therefore, it is crucial to develop materials that can shield devices and humans from exposure to electromagnetic radiation. In this context, nanocomposite materials offer huge advantages due to the dual possibility of tailoring the interfaces as well as using the complementary properties of magnetic and dielectric components in the nanocomposite to enhance the EMI shielding performance. This work shows that by a careful tuning of the synthesis parameters, we can grow biphasic lithium iron oxide (ferrimagnetic α-LiFe5O8 and paramagnetic α-LiFeO2) nanocomposite with different relative fractions of the two phases. The variation of the phase fraction and the simultaneous growth of the two phases allow us to control the interfaces between the two phases as well as the physical properties of the nanocomposite, which have a direct effect on the EMI shielding performance. Detailed structural (X-ray diffraction), compositional (Raman spectroscopy), and morphological (high-resolution transmission electron microscopy) characterization is presented to understand the effect of the synthesis conditions on the EMI shielding parameters. Improved dielectric and magnetic properties together with an increased number of interfaces in the sample with nearly equal amounts of the two phases results in the best performance. This work demonstrates the significant potential of using biphasic magnetic oxide nanocomposites with controllable interfaces and physical properties for EMI shielding, which can form the base for more complex triphasic systems in the future.