Chemical synthesis of air-stable manganese nanoparticles.

Elemental manganese has a complex crystal structure and unusual magnetic properties, making it an intriguing target for exploration in nanocrystalline form. However, because of its oxophilicity and the difficulty in reducing soluble metal salts to elemental Mn using the most common solution-phase reducing agents, it has been challenging to synthesize and stabilize elemental Mn nanoparticles using solution chemistry methods. Here we report the chemical synthesis of alpha-Mn nanoparticles using n-butyllithium as a reducing agent. The nanoparticles have been characterized by powder XRD, TEM, electron diffraction, infrared spectroscopy (DRIFT), XPS, and SQUID magnetometry. An amorphous manganese oxide layer bound by oleate ligands helps to render the nanoparticles air-stable. The oxide-coated alpha-Mn nanoparticles are paramagnetic.