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Final agenda 4.5.06

 

Workshop 10

Thursday, May 4
Bldg. 401, A5000
8:30 am - 12:00 pm

Diffuse Scattering: Emerging Opportunities with Advanced X-ray and Neutron Sources

Organizer:
Gene Ice, Oak Ridge National Laboratory (IceGE@ornl.gov, 865-482-6535)

To Agenda >


Diffuse scattering is a powerful probe of local correlations with sensitivity to defects, surfaces, dynamics, interfaces, and other structures with short-range periodicity. The development of intense x-ray sources and the development of more powerful neutron sources has created new opportunities with the potential to revolutionize our understanding of short-range correlations in materials. In this workshop we present prototype experiments that demonstrate the range of science that can now be addressed with diffuse scattering and that highlight major opportunities for materials discovery now possible. Talks will include a discussion of the ability to study dynamics of atomic motion (thermal-diffuse scattering) in-situ, in real time and in combinatorial studies. This work is only possible due to the development of efficient x-ray area detectors and intense x-ray beams. Another talk will highlight the role of modeling to extract key features of atomic dynamics and local structure in materials and will discuss new opportunities made possible by this approach. Combined diffuse/microbeam experiments will also be discussed. Here the ability to make intense x-ray micro/nanobeams that can measure weak diffuse scattering in very small samples offers enormous--and as yet largely untapped--potential for studying materials where large homogeneous samples are hard to make, where large samples may be dangerous, or where naturally occurring samples are polycrystalline by nature.  Other talks will discuss surface and interface scattering and how diffuse scattering can be used to characterize structure with limited range in one dimension. It is the goal of this workshop, to both teach the range of new science now emerging and to develop an understanding of where better instrumentation and/or software can enable the user community to access diffuse scattering as an essential tool of materials discovery.

Agenda as of April 4, 2006

8:30 - 8:40 Welcome and Introduction
Gene Ice, Oak Ridge National Laboratory
8:40 - 9:20 Diffuse Scattering and Models of Disorder: New Opportunities for Diffuse X-ray and Neutron Scattering
Richard Welberry, Australian National University, Canberra, Australia
(speaker profile)
9:20 - 10:00 Diffuse Scattering: Study of Bulk and Near-Surface Microstructure of Alloys
Bernd Schoenfeld, ETH Zurich
(speaker profile)
10:00 - 10:15 Break
10:15 - 10:50

Microbeam Measurements of Defect Distribution
Bennett Larson, Oak Ridge National Laboratory
(speaker profile)

10:50 - 11:25 Studies of Short-Range Order and Atomic Displacements in a Null Matrix 62Ni0.52Pt0.48 Crystal
Jose Abelardo Rodriguez, University of Houston
(speaker profile)
11:25 - 12:00 X-ray Diffuse Scattering Studies of Phonons and Phase Transitions
Tai Chang, University of Illinois at Urbana Champaign
(speaker profile)

 

Speaker Profiles

 

Professor Richard Welberry, Australian National University in Canberra, is a pioneer in the application of Least-Squares Monte Carlo methods for direct fitting of diffuse x-ray and neutron scattering. He has extensive experience with collecting and interpreting x-ray and neutron diffuse scattering and in the study of structures in materials with length scales on the order of 0.1-20 nanometers. These nanoscale structures are inherently inaccessible using conventional crystallography. His applications of diffuse scattering have included studies of functional material such as solid-state ionic conductors, relaxor ferroelectrics, guest/host inclusion compounds and measurements aimed at understanding the importance of nanoscale structure to materials properties. His talk will review recent diffuse scattering applications based on the use of synchrotron and neutron beams.
Professor Bernd Schoenfeld, Institut für Angewandte Physik, ETH Zurich is a master researcher, respected for his careful sample preparation methods designed to achieve reproducible diffuse scattering measurements. His comparison of alternative data analysis methods have shed light on best practices for determining local correlations in materials. His recent work on local structure near surfaces is only possible because of intense synchrotron radiation. His talk will discuss the use of diffuse x-ray and neutron scattering to study bulk and near-surface microstructure of alloys.
Dr. Bennett Larson, Oak Ridge National Laboratory, is a long-time pioneer in the field of diffuse scattering from defects and is pioneering new science in the area of micro and nanodiffraction. His work on ion-implanted materials demonstrates that spatial resolution combined with advanced single-crystal diffuse scattering methods can provide important new information about defects and their distributions in materials. His talk will discuss the potential for combining microbeam and diffuse scattering methods to understand how defects are organized in materials.
Dr. Jose A. Rodriguez, University of Houston, has been working with Prof. Simon C. Moss on diffuse scattering from disordered alloys. Dr. Rodriguez will discuss the application of diffuse x-ray and neutron scattering to understand subtle reciprocal space influences on local real-space structure and order in NiPt alloys using the null-matrix technique.
Dr. Tai-Chang Chiang, University of Illinois at Urbana Champaign, has done seminal work on bulk, surface and interface states of metals and semiconductors. He has pioneered rapid, in-situ x-ray studies of TDS in single crystals. These methods offer hope for studies of atomic across phase transitions, and during processing for combinatorial studies of differences in atomic motions due to differences in processing and/or alloy composition.