An investigation into beam damage of mesoporous materials

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In 1992, researchers at Mobil Research and Development created a new class of porous silicates, most notably mesoporous MCM-41. This material features a hexagonal arrangement of linear pores and surface areas in excess of 1,000 m{sup 2} g{sup {minus}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{sup {minus}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 ... continued below

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4 p.

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Blanford, C.F.; Stein, A.; Carter, C.B. & Bentley, J. February 1, 1998.

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In 1992, researchers at Mobil Research and Development created a new class of porous silicates, most notably mesoporous MCM-41. This material features a hexagonal arrangement of linear pores and surface areas in excess of 1,000 m{sup 2} g{sup {minus}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{sup {minus}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 structure but resulted in energy-filtered TEM elemental maps of oxygen K and Ti L(2,3) edge intensities that were too noisy to reveal structure at 5 nm resolution. Similarly, EDS spectrum images ({approximately} 0.5 nA for 0.5 s in 5 nm pixels) produced Si, S, and Ti (K) maps that were too noisy to reveal structure at 10 nm resolution. In order to improve the stability of MCM-41 and to extend applicability of TEM to these materials, it is necessary to understand the pathways by which the pore structure is damaged. It was found that the stability of MCM-41 is affected by several variables in the synthesis such as the silicate source, pH, and the reaction temperature. By correlating the changes in synthesis to changes in microstructure, it should be possible to fine-tune the material synthesis to produce a material on which high-resolution analytical electron microscopy can be performed.

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4 p.

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OSTI as DE98004937

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  • Microscopy and microanalysis 1998, Atlanta, GA (United States), 12-16 Jul 1998

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  • Other: DE98004937
  • Report No.: ORNL/CP--96795
  • Report No.: CONF-980713--
  • Grant Number: AC05-96OR22464
  • Office of Scientific & Technical Information Report Number: 650190
  • Archival Resource Key: ark:/67531/metadc710761

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  • February 1, 1998

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  • Sept. 12, 2015, 6:31 a.m.

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  • Jan. 19, 2016, 6:53 p.m.

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Blanford, C.F.; Stein, A.; Carter, C.B. & Bentley, J. An investigation into beam damage of mesoporous materials, article, February 1, 1998; Tennessee. (digital.library.unt.edu/ark:/67531/metadc710761/: accessed October 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.