Insights into the optical, magnetic and dielectric properties of some novel polysulfone/NiFe2O4 composite materials

Novel polysulfone (PSU)/NiFe2O4 nanocomposites with good magneto-dielectric properties were prepared in a simple and cost-effective manner. Nickel ferrite nanoparticles exhibit a cubic spine! phase without any impurity phases according to X-ray diffraction characterization. Transmission electron microscopy images of the nanoparticles showed a tetragonal particle shape with average particle size of 17-30 nm. The thermal stability of PSU proved to remain unaffected by nanoparticle concentration in the composite material. The emission spectra of the PSU/NiFe2O4 nanocomposites present a broad emission band located at 370 nm due to free exciton recombination. The composites exhibit hysteresis loops of a ferrimagnetic nature and good dielectric properties. Coercivity value measured at room temperature is 20.64 and 24.98 Oe and the squareness (M-r/M-s) is 0.290 and 0.225 for both polymer composite samples (4 and 24 vol% Ni ferrite). The formalism of the dielectric loss has been used to estimate the dipolar relaxations expressed by gamma- and beta-relaxation processes. The presence of Ni ferrite nanoparticles in the PSU matrix increases the activation energy of secondary relaxations, which means a reduction of the molecular mobility in the nanocomposites as compared to PSU. (C) 2018 Society of Chemical Industry