X-ray studies of nanoporous gold: Powder diffraction by large crystals with small holes

Abstract

X-ray diffraction studies of nanoporous gold face the poorly understood diffraction scenario where large coherent crystals are riddled with nanoscale holes. Theoretical considerations derived in this study show that the ligament size of the porous network influences the scattering, despite being quasi single crystalline. Virtual diffraction of numerically generated samples confirms the results but also shows a loss of long-range coherency and the appearance of microstrain due to thermal relaxation. Subsequently, a large set of laboratory x-ray investigations of nanoporous gold fabricated by different approaches and synthesis parameters reveal a clear correlation between ligament size and size of the coherent scattering domains, as well as extremely high microstrains in samples with ligament sizes below 10 nm.