Improving electron tomography of mesoporous silica by Ga filling

Abstract: Electron tomography (ET) offers nanoscale 3D characterization of mesoporous materials but is often limited by their low scattering contrast. Here, we introduce a gallium (Ga) intrusion strategy for mesoporous silica that dramatically improves imaging contrast – a key benefit that enables more accurate 3D reconstructions. By infiltrating Ga through a modified mercury intrusion porosimetry process, the high-angle annular dark-field (HAADF) STEM signal is enhanced by 5 times, resulting in a 34% improvement in reconstruction resolution and a 49% sharpening of interface definition. In addition, the increased sample conductivity simplifies focused ion beam (FIB) milling by reducing charging and drift. This approach facilitates precise segmentation and quantitative analysis of pore connectivity and size distribution, thereby extending the applicability of ET for light-element, non-conductive materials and advancing structure-property characterization of complex porous systems.