Meeting report

Methods of high-pressure single-crystal X-ray diffraction

Darmstadt, Germany, September 2010

[Workshop attendees] Participants at the High-pressure Single-crystal X-ray Diffraction Workshop

Single-crystal diffraction provides the most accurate structural data on the compression of crystalline solids. The methods for high-pressure diffraction developed over the last 3 decades are mature and easy to use in both the laboratory and at synchrotron sources, but are not well known throughout the crystallographic community. In summer 2008 a group of high-pressure crystallographers from Europe and the USA met in Padova, Italy to discuss how to promote high-pressure single-crystal methods. On the occasion of a second meeting a year later in Copenhagen, Denmark, we agreed to meet on a regular basis and decided to offer an open workshop in association with the 26th European Crystallography Meeting held in Darmstadt, Germany (September 3-4, 2010).

The workshop, hosted on the campus of TU Darmstadt and organised by R. Miletich, A. Grzechnik and H. Ehrenberg, attracted 50 participants. A general overview of the entire workflow for a high-pressure experiment, and the additional challenges to be overcome compared to ambient-pressure measurements, was given by R. Angel. The first morning featured presentations by R. Miletich, C. Hejny and B. Periotto on diamond cells, how to load them, and then perform the data collections on the diffractometer. In the afternoon M. Alvaro reviewed software for data integration, before the workshop split into separate sections in which R. Angel, D. Gatta, T. Balic-Zunic and A. Grzechnik showed how to integrate high-pressure data with several commercial and freeware software packages. The second day was devoted to the separate subjects of equations of state (T. Boffa-Ballaran) and intensity data reduction and refinement (K. Friese, R. Angel), followed by structure validation and structure analysis (T. Balic-Zunic, K. Friese). The majority of the second afternoon was devoted to discussing detailed data issues with the participants, along with a demonstration by the research group of R. Miletich of preparing and loading diamond-anvil cells. The workshop was concluded with a short presentation by H. Ahsbahs on the design of a new generation of diamond cells, and a review of synchrotron beamlines available for single-crystal diffraction.

The workshop participants included researchers from many fields (chemistry, physics, geology, and materials science) at all levels of experience with high-pressure single-crystal X-ray diffraction. More than one third of the participants were PhD students. Comments on the presentations are available at www.crystal.vt.edu/crystal/hpworkshop.html.

We would like to acknowledge the generous support of Agilent Technologies (formerly Oxford Diffraction), Stoe & Cie GmbH, Incoatec GmbH and Scimed GmbH that allowed us to offer travel grants to some student participants, and to cover catering costs.

Ross Angel and Andrzej Grzechnik