The density and compressibility of nanoscale gold (both nanospheres and nanorods) and microscale gold (bulk) were simultaneously studied by X-ray diffraction with synchrotron radiation up to 30 GPa. Colloidal stability (aggregation state and nanoparticle shape and size) in both hydrostatic and nonhydrostatic regions was monitored by small-angle X-ray scattering. We demonstrate that nonhydrostatic effects due to solvent solidification had a negligible influence on the stability of the nanoparticles. Conversely, nonhydrostatic effects produced axial stresses on the nanoparticle up to a factor 10× higher than those on the bulk metal. Working under hydrostatic conditions (liquid solution), we determined the equation of state of individual nanoparticles. From the values of the lattice parameter and bulk modulus, we found that gold nanoparticles are slightly denser (0.3%) and stiffer (2%) than bulk gold: V₀ = 67.65(3) ų, K₀ = 170(3)GPa, at zero pressure.

中文翻译：

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金在纳米级的硬度

通过同步辐射高达 30 GPa 的 X 射线衍射同时研究纳米级金（纳米球和纳米棒）和微米级金（块状）的密度和可压缩性。通过小角度 X 射线散射监测流体静力学和非静力学区域的胶体稳定性（聚集状态和纳米颗粒形状和尺寸）。我们证明了由于溶剂固化引起的非流体静力效应对纳米颗粒的稳定性的影响可以忽略不计。相反，非流体静力效应在纳米颗粒上产生的轴向应力比在块状金属上产生的轴向应力高 10 倍。在流体静力学条件下（液体溶液），我们确定了单个纳米粒子的状态方程。从晶格参数和体积模量的值，V ₀ = 67.65(3) Å ³，K ₀ = 170(3)GPa，在零压力下。