Flame synthesis of superparamagnetic Fe/Nb nanocomposites for biomedical applications

Iron/niobium nanocomposite particles are produced using the sodium flame and encapsulation (SFE) process. Ferrocene is added to the vapor-phase metal halide/sodium reaction to produce metallic iron particles encapsulated in niobium. To accomplish this, the ferrocene is combined with niobium chloride vapor and this mixture is injected as a turbulent jet into a stream of sodium vapor. The ferrocene is expected to decompose upstream of the flame to form iron particles, which pass through the niobium chloride-sodium reaction zone wherein they are encapsulated in niobium. The salt byproduct then encapsulates these particles, preventing oxidation. The as-produced Fe/Nb particles were found to contain Fe particles that are less than ∼15 nm in diameter and are superparamagnetic with a coercivity of 50 Oe and a saturation magnetization of over 200 emu/g of Fe. In addition to possessing a strong magnetic response and small remnant magnetization, the iron/niobium composite particles are expected to be biocompatible and X-ray opaque. Consequently, these materials hold promise for magnetic navigation in biomedical applications.