Magnetic properties and heating efficacy of magnesium doped magnetite nanoparticles obtained by co-precipitation method

Abstract Ferrofluids based on magnesium substituted magnetite nanoparticles Mg x Fe 3−x O 4 (x = 0.1; 0.2; 0.4) were synthesised by a chemical co-precipitation method. Their physical properties have been compared with those of the magnetite based ferrofluid obtained by the same synthesis route. Both XRD and TEM studies showed particle size decrease with the increased Mg content while DLS experiments pointed to the more prominent aggregation of Mg-containing nanoparticles. Magnetic properties investigation conducted on the powder (i.e. dried) specimens showed decrease of magnetization values with increased Mg content except for the lowest concentration of x = 0.1 where substantial saturation magnetization rise of about 40% was recorded at room temperature. Heating abilities of the studied ferrofluids under the applied AC fields (SAR values) also showed decreasing trend with the increased Mg content even for x = 0.1 sample despite its elevated magnetization value. This trend has been understood as a consequence of the changed intrinsic nanoparticle properties such as size and magnetic anisotropy, as well as contribution of a collective behaviour due to an increased nanoparticle aggregation in Mg-doped systems.