Thermophysical and Magnetic Properties of Carbon Beads Containing Nickel Nanocrystallites

Abstract

Ferromagnetic and superparamagnetic nickel nanocrystallites, stabilized in a carbon matrix, were prepared by a three-step procedure including formation of a Ni acrylamide complex, followed by frontal polymerization and pyrolysis of the polymer at various temperatures. It was found that the procedure applied enables fabrication of magnetic beads containing metallic nanocrystallites embedded in a carbon matrix. The size of the crystallites, their morphology, volume fraction, and magnetic properties can be tailored by the pyrolysis temperature. The size of the crystallites affects their behavior in an external magnetic field, i.e., a heating process is the most effective for a sample pyrolyzed at 873 K. The revealed H n -type dependence of the temperature increase rate, (dT /dt) t=0 , on the amplitude of the magnetic field indicates the presence of both superparamagnetic and ferromagnetic particles in all the samples studied since n > 2. For the superparamagnetic particles, the heating mechanism is associated with Néel relaxation. For the lower values of the magnetic field amplitude, H < H 0 , the relaxation losses dominate whereas for the opposite case, H > H 0 , the magnetic hysteresis is the main source of thermal energy losses. The composites containing magnetic Ni nanocrystallites entrapped in a carbon matrix can be potentially applied for hyperthermia treatment.

Polymer-Assisted Synthesis, Structure and Magnetic Properties of Bimetallic FeCo- and FeNi/N-Doped Carbon Nanocomposites

“…The subsequent controlled thermolysis of the resulting metallopolymers or the controlled transition of FP to the combustion mode leads to the formation of metal-polymer nanocomposites. Previously, we synthesized monometallic M@N-doped carbon nanocomposites with a core-shell structure based on Co(II), Ni(II), Fe(III) acrylamide complexes as precursors, in which the carbonized polymer shell protects the metal core from oxidation and aggregation [57,58].…”

Phase Structure and Heat Generation in the Co-Precipitated Magnetite Nanoparticles

“…However, there are safety limits concerning both applied magnetic field and frequency range. So that amplitude of the magnetic field H should not be higher than 15 kA/m, while the frequency has to be in the range 0.05 MHz < f < 1.5 MHz [4].…”

Magnetic nanocomposites for biomedical applications

“…It might turn out particularly useful for biomedical in vivo applications in diagnostic applications such as MRI [1] and therapies such as sitespecific drug delivery [2,3] and magnetic particle hyperthermia [4,5]. MCNCs, in a form of microparticles (or microspheres), with embedded magnetic cores are especially proposed for in vitro applications [6,7] e.g.…”