AFM observation of nanocrystalline Au prepared by a gas deposition method

We investigate the surface morphology of nanocrystalline Au (n-Au) specimens prepared by a gas deposition (GD) method as well as the effect of 20 MeV proton irradiation at 1.5 K on the elastic properties of the n-Au specimen. It is suggested that small clusters of 10–20 ultrafine particles are simultaneously formed during the formation of the ultrafine particles above the Au melt. The large decreases in the low-temperature Youngʹs modulus (ΔE) after proton irradiation are found, where (ΔE/E)/CFP is 10 to 102 times larger than those reported for bulk metals (CFP, concentration of Frenkel-pairs). We give a brief statement for this reasoning that such a large (ΔE/E)/CFP reflects a diaelasticity associated with some modifications of the grain boundaries owing to irradiation-induced defects.