Affiliation:
1. Honorary Prof. School of Mechanical, Materials Mechatronic and Biomedical Engineering University of Wollongong NSW 2522 Australia
2. Dept. of Materials Science Faculty of Science Srinakharinwirot University Bangkok 10110 Thailand
3. School of Mathematical and Physical Sciences University of Technology Sydney PO Box 123 NSW 2007 Australia
Abstract
AbstractThe formation of mesoporous gold sponges by explosive decomposition of ‘knallgold’ (also known as ‘fulminating’ gold) is studied. Proof‐of‐principle experiments are conducted and then the phenomena are further investigated using ‘toy physics’ molecular dynamics simulations. The simulations invoked various ratios of a volatile Lennard–Jones element G and a noble metal element N. In both experiment and simulation the morphology of the resulting sponge is found to depend on the stoichiometry of the starting material. As the mole fraction of G (χG) is increased from 0.5 to close to 1.0 in the simulations, the morphology of the sponges changes from closed to open, with a corresponding increase in the average mean curvature from 0 to +0.12 inverse Lennard–Jones length (L) units. The average Gaussian curvature of the simulated sponges is always negative, with the minimum value of 0.05 L−2 being found for χG≈0.65. In broad agreement with experiment, sponge formation in the simulations is bounded by stoichiometry; no sponges form if χG is <0.52, for χG between 0.52 and 0.70 the sponge is characterized by vermicular cavities whereas classic bicontinuous fibrous sponges form for 0.70<χG<0.85 and, finally, discrete particles result if χG>0.85.