The development of high-resolution X-ray powder diffractometer using laboratory source for an advanced structural analysis

Department of Applied Physics, Nagoya University
â—‹Shinobu Aoyagi Hiroyuki Suwa Takeshi Nakashima Eiji Nishibori Makoto Sakata

Recently, advanced structural analyses, such as charge density analysis and ab-initio structure determination, from powder sample have been carried out in the wide range of materials science fields. These studies require high-resolution X-ray powder diffraction data with high counting statistics compared to conventional powder structural refinement. There are large demands for a powder diffractometer available to the advanced structural analysis based on laboratory X-ray source. In this study, we developed a high-resolution powder diffractometer with Imaging Plate (IP) as a detector using laboratory source.
The detailed specs of the diffractometer are as follows. The X-ray source is Rigaku ultraX 18, an 18 kW rotating anode generator, with a Mo target. The X-ray optics consists of a curved graded multilayer mirror (MM) and two Ge channel-cut monochromators (CCM). Three different optical systems, MM, MM with one CCM and MM with two CCM, are available. The X-ray intensities for each optical system at sample position are approximately ~109 for MM, ~107 for MM with one CCM and ~106 for MM with two CCM, cps. Diffraction pattern is recorded on a curved IP, which can simultaneously collect a wide d-spacing range (> 0.58 A).
We measured powder diffraction data of various kinds of materials by the diffractometer in MM with one CCM optical system. The whole powder pattern of diamond, including 222 forbidden reflection due to the bonding electron, was collected by 24 hours X-ray exposure. Ab-initio structure determination including hydrogen atoms of cytidine was successfully carried out from the data collected by 2.5 days exposure. The present results indicate that our diffractometer has an ability to collect a powder data for the advanced structural analysis in a few days.