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An Investigation Into Beam Damage of Mesoporous Materials

Published online by Cambridge University Press:  02 July 2020

C. F. Blanford
Affiliation:
Department of Chemistry, University of Minnesota, 207 Pleasant St. S.E., Minneapolis, MN55455-0431
J. Bentley
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN37831-6376
A. Stein
Affiliation:
Department of Chemistry, University of Minnesota, 207 Pleasant St. S.E., Minneapolis, MN55455-0431
C. B. Carter
Affiliation:
department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. S.E., Minneapolis, MN55455-0132
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Extract

In 1992, researchers at Mobil Research and Development created a new class of porous silicates, most notably mesoporous MCM-41.2-3 This material features a hexagonal arrangement of linear pores and surface areas in excess of 1000 m2 g-1. MCM-41 exhibits narrow pore size distributions in the nanometer range. The walls of MCM-41 are essentially amorphous silica, but its porous nature makes it about 3 kJ mol-1 less stable than the collapsed form. Particles of MCM-41 are beam sensitive and it appears that they cannot withstand the large current densities required to obtain reliable analytical data at the nanometer scale in the transmission electron microscope (TEM). For example, low beam currents were used to preserve the pore structure but resulted in energy-filtered TEM elemental maps of oxygen K and Ti L2,3 edge intensities that were too noisy to reveal structure at 5 nm resolution.

Type
Nanophase and Amorphous Materials
Copyright
Copyright © Microscopy Society of America

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7. Research at ORNL SHaRE User Facility sponsored by the Division of Materials Sciences, U.S. Department of Energy, under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corp., and through the SHaRE Program under contract DE-AC05-76OR00033 with Oak Ridge Associated Universities. C.F.B. also acknowledges the Center for Interfacial Engineering (CIE), an NSF Engineering Research Center, for financial support.