Enhancement of L10 phase formation in FePt nanoparticles by nitrogenization

FePt particles 6 nm in size are produced by argon/nitrogen sputtering and gas-phase condensation. Marked changes in the atomic structure and morphology of the particles occur upon addition of nitrogen to the sputter gas. Electron energy loss spectroscopy and x-ray absorption spectroscopy show that nitrogen is incorporated in the particles in molecular and compound form. In situ sintering of the particles drives out the nitrogen causing enhanced diffusion leading to the preference of the L1(0) structure over the multiply twinned icosahedral structure, which forms in the absence of nitrogen in the sputter gas.