Nearly Monodispersed Multifunctional NiCo2O4 Spinel Nanoparticles: Magnetism, Infrared Transparency, and Radiofrequency Absorption

We report low temperature synthesis of nearly monodispersed NiCo2O4 nanoparticles by a combustion method utilizing glycine as a fuel and nitrate as oxidizer. An appropriate glycine-to-metal nitrate molar ratio favors the formation of nearly monodispersed NiCo2O4 nanoparticles. We discuss the relevant synthesis chemistry and their detailed characterization using different techniques such as X-ray diffraction, high resolution transmission electron microscopy, superconducting quantum interference device magnetometry, and Fourier transform infrared spectroscopy. We also show the interesting evolution of the phase and magnetic properties of such nanoparticles upon annealing treatment. Importantly, these nanoparticles show a high (∼83%) infrared transparency that is useful for specific solar and fuel cell electrode applications as well as significant radiofrequency (RF) absorption causing substantial heating of their aqueous dispersion that should have potential applications for magnetic hyperthermia.