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Workshop 6—High-energy X-rays on Single Crystals: A Unique Capability at the APS

Wednesday, May 8, 2013 (afternoon)
Bldg. 402, Rm. E1200

Organizers: Alan I. Goldman (Iowa State U.) and Jonathan C. Lang (APS)

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OVERVIEW

A key distinguishing feature of the Advanced Photon Source (APS) is the capability for high-energy scattering, which has been exploited for numerous applications including pair distribution function studies, high pressure studies, and investigations of the mechanical behavior of materials. Coupled with the new generation of two-dimensional area detectors, high-energy diffraction studies of polycrystalline samples provide an important approach to structural measurements complementary to conventional x-ray and neutron diffraction measurements. The capabilities for high-energy single-crystal diffraction measurements at the APS, however, have only recently matured. The advantages of high-energy x-rays for diffraction studies have been widely discussed and were, for example, the topic of an APS sponsored workshop as early as 2001. Of particular importance, the use of high-energy x-rays ensures that the structure of the sample bulk, rather than near surface region, is probed and, because of the short wavelength (typically < 0.1 Å), the diffraction pattern is concentrated to smaller angles allowing the efficient use of area detectors and rapid data acquisition. Furthermore, the penetrating power of high-energy x-rays eases constraints on the use of ancillary equipment such as cryostats, pressure cells and magnets, which impose limitations on the angular access to the sample.

Over the past few years several groups working at the APS have developed techniques using high-energy x-rays to image both Bragg and diffuse scattering in reciprocal space, and applied these methods to a variety of phenomena governed by complex atomic disorder, both in the form of point defects and the nanoscale self-organization e.g. in the form of stripes, phase separation, or dimerization, which result from the competition between interactions with incompatible order. Examples include the high temperature cuprate and iron pnictide superconductors, colossal magnetoresistance materials, relaxor ferroelectrics, as well as investigations of rotational disorder in molecular solids and intercalation compounds, adsorption in microporous frameworks, and quasicrystals. We seek to expand the community of users for these single crystal methods through a workshop that introduces the unique capabilities at the APS for high-energy x-ray single crystal investigations and, at the same time, explores the requirements and interests of future users.

AGENDA

1:30 Alan Goldman (Ames Laboratory and Iowa State University)
Overview and Goals of the Workshop
1:45 Andreas Kreyssig (Ames Laboratory)
Imaging of Reciprocal-space Planes by a High-energy X-ray Precession Camera
(abstract)
2:15 Markus Hücker (Brookhaven National Laboratory)
Competing Electronic States in Cuprate Superconductors (abstract)
2:45 Manuel Angst (Jülich Research Center, Germany)
Probing Charge–order–based Multiferroicity by High-energy X-rays
(abstract)
3:15 Break
3:30 Richard Welberry (Australian National University)
Polar Nanoregions and Diffuse Scattering in Relaxor Ferroelectrics
(abstract)
4:00 Ray Osborn (Argonne National Laboratory)
Single-crystal Diffuse Scattering Using High-energy X-rays (abstract)
4:30 Yu Wang (Michigan Technological University)
Three-dimensional Diffuse Scattering Study of Phase Transition Precursor Phenomenon Using In Situ High-energy X-ray Single-crystal Diffraction (abstract)
5:00 Jonathan Lang (Advanced Photon Source)
Summary and Open Discussion
5:30 Adjourn

Updated 04/23/13