Morphological and topological analysis of coarsened nanoporous gold by x-ray nanotomography

Abstract

We used x-ray nanotomography to characterize the three-dimensional ͑3D͒ morphology and topology of dealloyed nanoporous gold after coarsening. The interface shape distribution obtained from the nanotomography measurement shows that the coarsening does not proceed by bulk diffusion. The surface normal distribution shows that the morphology of the nanoporous gold is anisotropic. The topology of nanoporous gold is similar to that of other bicontinuous structures created by phase separation, despite the radically different method used to produce the structures. This work opens the door to time-resolved, in situ studies of coarsening of nanoporous gold in 3D.

Nanoporous Gold Electrodes and Their Applications in Analytical Chemistry

“…This method is an ideal way to see the inner pore network, the bicontinuous nature of nanoporous gold, and quantitatively evaluate the curvature and the average diameter of the ligaments and nanopore channels [91,92]. Transmission X-ray microscopy using a synchrotron X-ray source has also been used to examine the 3D microstructure of a coarsened sample tens of microns thick [93]. Recently, this method has been used to study the coarsening of nanoporous gold at different temperatures [94].…”

Effect of thermal coarsening on the thermal conductivity of nanoporous gold

“…Dealloying [2,3] is commonly used to fabricate NPG by dissolving a less noble constitution from the initial alloy, leaving a three-dimensional bicontinuous porous Au network structure. To meet various needs, different NPG structures have been made, including the film on substrate [4][5][6], freestanding beam [4,7], cantilever [4], thin foils [2,3,[8][9][10][11][12], and micro/ nanowires [13,14]. In these structures, the porous morphology varies with the different dealloying processes or geometric boundary conditions [4], and the precise control of microstructural morphology is difficult.…”

Image reconstruction from sparse data in synchrotron-radiation-based microtomography

“…1 Today, both commercial micro-CT systems and synchrotronradiation-based CT systems can achieve around 1-μm resolution without x-ray optics, [2][3][4][5][6] and sub-50-nm resolution with x-ray optics. [6][7][8][9] In terms of microtomography, a thirdgeneration synchrotron radiation source provides partially coherent x-ray beam with enough brilliance to image a millimeter-sized sample at better than 10/micropixel resolution in a few seconds with high sensitivity. [10][11][12] In comparison to other nondestructive inspection techniques, such as magnetic resonance imaging, conventional micro-CT, and confocal microscopy, synchrotron-radiation-based micro-CT (SR-μCT) provides the unique capability of performing 3D dynamic studies.…”