Magnetic NiFe$_2$O$_4$ nanoparticles functionalized for magnetic powder imaging (MPI)

The properties of NiFe$_2$O$_4$ magnetic nanoparticles (MNPs) synthesized by the hydrothermal method, as well as the dependence of the properties on the functionalization (coating) of the particles with citric or polyacrylic acids by the coprecipitation method are studied. The properties of the obtained MNPs are studied by X-ray diffractometry (XRD). The magnetic properties of the samples and the phase state of the MNPs are studied using the physical property measurement system (PPMS) and Mössbauer spectroscopy. It is found that when NiFe$_2$O$_4$ MNPs are functionalized, citric or polyacrylic acids cover individual particles with shells, which reduces segregation and interaction of MNPs with each other, as a result of which the nanoparticles acquire superparamagnetic properties, which is extremely necessary for the latest technique of magnetic powder visualization of human organ diseases.