Structural and Magnetic Properties of Different Shape Gold Nanoparticles

In this study, different shape of gold nanoparticles were prepared by seed-mediate growth method and investigated by the measurements of ultraviolet-visible (UV/Vis) spectrometer, transmission electron microscopy (TEM), X-ray diffractometer (XRD), and superconducting quantum interference device (SQUID). When the dosage of gold seed (DGS) is smaller than 0.03 mL or greater than 0.03 mL, the aspect ratio of gold nanorods will diminish, and the output of gold nanoparticles will also decrease. Therefore the optional condition for preparation of gold nanorod is DGS=0.03 mL. While DGS increases to 0.5 mL, the shape of the gold nanoparticles is changed form rod to sphere. There are weak ferromagnetism observed in the results of magnetization for gold nanorods and spherical nanoparticles under -2000 to 2000 Oe at 5K, and the coercive fields are 226 Oe and 66 Oe for the gold nanorods and spherical gold nanoparticles, respectively.