Abstract: The present teachings are directed towards a thermolysis method of producing iron-containing nanoparticles by providing an iron-containing component, a colloid stabilizing component, and an amount of water. The iron-containing component, the colloid stabilizing component, and the amount of water form a mixture, which is then heated to a temperature sufficient to form iron-containing nanoparticles, which are then isolated from the mixture. Another method is also provided which involves a repetitive shell growth method of producing iron-containing nanoparticles by providing a first amount of an iron-containing component and a colloid stabilizing component; the iron-containing component and the colloid stabilizing component are then mixed and heated to a temperature sufficient to form iron-containing nanoparticles.