Ligand-Stabilized CoO and NiO Nanoparticles for Spintronic Devices with Antiferromagnetic Insulators.

Cobalt oxide (CoO) and nickel oxide (NiO) nanoparticles, coordinated by oleylamine, oleic acid and trioctylphosphine oxide, were prepared as antiferromagnetic materials in 1-octanol or 1-dodecanol by rapid synthesis under microwave irradiation. Structural analysis of the finally-obtained oxide nanoparticles was performed by means of X-ray diffraction, high-resolution transmission electron microscopy, and extended X-ray absorption fine structure measurements, which suggested that the higher temperature in 1-dodecanol (at 523 K) than in 1-octanol (at 463 K) enhanced the reaction efficiency in the preparation of NiO nanoparticles. The dependence of reaction condition (reaction temperature, starting organometallic precursor, solvent, additives, etc.) on the structure (particle size and polydispersity) was demonstrated. The magnetic properties of CoO and NiO were examined by means of a vibrating sample magnetometer, which indicated the antiferromagnetic structure of the pure CoO and NiO nanoparticles.