| AVS 64th International Symposium & Exhibition | |
| Advanced Ion Microscopy Focus Topic | Thursday Sessions |
| Session HI+BI+NS+TR-ThM |
| Session: | Advanced Ion Microscopy Applications |
| Presenter: | Holland Hysmith, Oak Ridge National Laboratory |
| Authors: | M.J. Burch, Oak Ridge National Laboratory A.V. Ievlev, Oak Ridge National Laboratory H. Hysmith, Oak Ridge National Laboratory K. Mahady, University of Tennessee P.D. Rack, University of Tennessee L. Luo, ExxonMobil Chemical Company A. Belianinov, Oak Ridge National Laboratory S. Yakovlev, ExxonMobil Chemical Company O.S. Ovchinikova, Oak Ridge National Laboratory |
| Correspondent: | Click to Email |
Porous materials are some of the most important modern day material systems, as the pore structure defines many materials applications and functionality. The pore structure of catalyst precursor particles, in particular, is of great importance to the catalyst community, as this pore structure dictates the efficiency and efficacy of grown polymers. However, despite the importance of these materials systems, there are few techniques to analyze pore size and structure. The most common technique is gas absorption, where the amount of gas absorbed and desorbed from a known amount of material is tracked and the average pore volume and size can be extracted. However, the technique is heavily dependent on sample quality and which fitting model is used to calculate volume and size. In addition, the technique is quite slow, where generally at most a single sample can be analyzed a day.
In this work, we demonstrate a novel technique to directly image and quantify pore size in nano-porous catalyst precursor particles via helium ion microscopy. We demonstrate the technique by directly imaging the surface pore structure of SiO2 precursor catalyst particles with helium ion microscopy. Using modern day data analytics, we created an automated routine to extract pore size and distributions. We show that our HIM based technique shows comparable data to the industry standard gas absorption technique, within a 5 percent difference between the techniques of a known porous samples.
Further, to determine the effect of the helium beam on the surface of the SiO2 particles, we simulate the beam interaction between porous SiO2 particles and the helium beam. At low ion doses the surface modification by the ion beam is quite negligible, where at higher ion doses, significant surface modification is observed.
In conclusion, we’ve demonstrated a novel technique to directly visualize and quantify nano-pore size and structure in SiO2 that yields complimentary data to gas absorption.
Acknowledgements
This work was conducted at the Center for Nanophase Materials Sciences, which is a Department of Energy (DOE) Office of Science User Facility. The users acknowledge the ExxonMobil Chemical Company for funding.