Structural analysis of rattle-type hollow mesoporous silica spheres using electron tomography and energy filtered imaging

Rattle-type hollow mesoporous silica spheres including an internal Fe2O3-containing particle were prepared using a carbon-iron template method. Elemental distribution of the silica spheres was analyzed using an energy-filter transmission electron microscopy, and the three-dimensional (3D) structure was visualized by a computer tomography with a scanning transmission electron microscopy (STEM). From the 3D structure reconstructed with a tilted series of high-angle annular dark field images, the diameter and shell thickness of the hollow mesoporous silica spheres were determined to be 381 +/- 14 and 61 +/- 10 nm. It was also found that the internal Fe2O3-containing particle with the diameter of 104 +/- 7 nm also exhibited a hollow structure with the shell thickness of 24 +/- 6 nm. Copyright (C) 2010 John Wiley & Sons, Ltd.