Reversible Phase Changes In Ge-Au Nanoparticles

We demonstrate a reversible phase transition in nanoparticles composed of a binary eutectic alloy, Ge-Au. The structure, 9 nm diameter nanoparticles embedded in silica, can be switched from bilobe to mixed using a 30 ns ultraviolet laser pulse. The structure can be switched back to bilobe by heating at 80 degrees C. The bilobe/mixed switching can be performed on the same sample at least ten times. Synchrotron X-ray diffraction studies reveal that the bilobe structure contains crystalline Ge and Au while the mixed structure consists of crystalline Ge and beta Ge-Au. (C) 2011 American Institute of Physics. [doi:10.1063/1.3584850]