High Dielectric Constant Liquid Dielectrics Based on Magnetic Nanofluids

Magnetic nanofluids are increasingly finding new applications. They can be employed as liquid dielectrics. The advantage of having a liquid dielectric is that high dielectric constant can be achieved by a judicious choice of the base liquid. The dielectric constant can be tuned with the help of an external magnetic field too. Superparamagnetic iron oxide nanoparticles were dispersed in polar carriers, namely water, polyvinyl alcohol, ethylene glycol, and a nonpolar carrier like kerosene to obtain stable magnetic fluids after ensuring the crystallographic phase purity along with appropriate magnetic characteristics of the dispersant. The fluids were then subjected to dielectric studies using an automated homemade dielectric setup. The dielectric permittivity and dielectric loss at different frequencies with and without an external magnetic field were evaluated. The studies indicate that magnetic nanofluids based on polar carriers are excellent liquid dielectrics over a wide range of frequencies with the incorporation of iron oxide nanoparticles. The application of an external magnetic field enhances the dielectric constant considerably. These magnetic nanofluids can be employed as liquid dielectrics for applications. It has been found that kerosene based magneto fluids have a low dielectric constant while Polyvinyl alcohol based fluids exhibit the highest dielectric constant.