Abstract
We describe the structural refinement of zeolite beta using the local structure obtained with the pair distribution function (PDF) method. A high quality synchrotron and two neutron scattering datasets were obtained on two samples of siliceous zeolite beta. The two polytypes that make up zeolite beta have the same local structure; therefore refinement of the two structures was possible using the same experimental PDF. Optimized structures of polytypes A and B were used to refine the structures using the program PDFfit. Refinements using only the synchrotron or the neutron datasets gave results inconsistent with each other but a cyclic refinement with the two datasets gave a good fit to both PDFs. The results show that the PDF method is a viable technique to analyze the local structure of disordered zeolites. However, given the complexity of most zeolite frameworks, the use of both X-ray and neutron radiation and high-resolution patterns is essential to obtain reliable refinements.
| Original language | English |
|---|---|
| Pages (from-to) | 55-66 |
| Number of pages | 12 |
| Journal | Microporous and Mesoporous Materials |
| Volume | 77 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 3 2005 |
Funding
The authors would like to thank Kaveri Sawant for the 29 Si MAS NMR spectra and Robyn J. Accardi for providing one of the beta samples. We would also like to thank Sarvjit Shastri at APS and Valeri Petkov for their help obtaining and reducing the X-ray data. Thanks to Sven Vogel at LANSCE for a neutron scattering dataset that was not included. Thanks to Chris Benmore for his help on the data reduction of the neutron data and Joan Stewie for her help performing the experiment at GLAD, IPNS. Funding of this work was partially provided by the National Science Foundation under Grant No. CTS-0085036. Use of the Advanced Photon Source was supported by the US Department of Energy, Basic Energy Sciences, Office of Science, under Contract No. W-31-109-Eng-38. The Intense Pulse Neutron Source is operated as a user facility by the US Department of Energy, Division of Materials Sciences, under Contract No. W-31-109-Eng-38. Los Alamos National Laboratory is funded by the US Department of Energy under contract W-7405-ENG-36.
Keywords
- Disorder
- Pair distribution function
- Stacking faults
- Structure refinement
- Zeolite beta