Rosensweig Instability Study of Iron Oxide Nano Fluid Under Uniform Magnetic Field

Abstract

We report the synthesis of magnetic nanofluids and the investigations on the formation of surface instabilities of ferrofluid when exposed to a normal uniform magnetic field. Ferrofluid of iron oxide particles with an average size of 9 nm, dispersed in a kerosene base is synthesized by a well-known chemical method. The structural analysis of the nanoparticles is carried out by employing X-ray diffraction technique. Fourier Transform Infrared Spectroscopy studies revealed the chemical binding with the surfactant. The Dynamic Light Scattering studies are performed to determine the hydrodynamic size of the suspended particles. The constancy in hydrodynamic size obtained for different particle concentrations is indicative of agglomeration-free suspension. The magnetic properties have been analyzed by the Superconducting Quantum Interference Device. The magnetization measurement signifies the superparamagnetic nature of particles. The temperature-dependent relaxation studies were carried out by field cooled (FC) and zero field cooled (ZFC) moment measurements at a constant applied field. We have demonstrated the Rosensweig instability experimentally and observed the pattern transition. The surface takes on a hexagonal pattern when the applied field surpasses the critical field, which shifts to a square pattern when the applied field reaches a second threshold. The surface tension of the fluid is measured by the pendant drop method and is correlated with the results obtained through instability measurement. The magnetic concentration of the sample is determined from the Thermo gravimetric analysis.