Synchrotron powder X-ray diffractometer beamline at J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices

The J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices (CAMD) is a synchrotron ring operating at 1.3 GeV, with the ring current typically ranging from 230 to 100 mA. An X-ray powder diffraction beamline was recently commissioned at CAMD at the bending magnet port 7A. The powder diffraction beamline consists of a Brazilian-designed double crystal monochromator, a Huber four-circle diffractometer, and a Canberra germanium solid-state detector. The monochromator is equipped with Si 111 and Ge 220 crystals. The Canberra high purity germanium solid-state detector has a resolution of 130 eV at Mn Kα. For typical use, the diffractometer circle is set to 17 cm, and the source and receiving slits have been set to 300 and 200 μm, respectively. A sample spinner is used for improved particle size averaging. Wavelength can be shifted in a matter of minutes. Preliminary runs of NIST standards, for example, lanthanum hexaboride (LaB6) (SRM 660a), show good performance over a wide two-theta range. Rietveld refinement of novaculite (SiO2) shows lower residual error for the same mineral compared to that obtained from a run with a conventional X-ray source. At the beamline, the user can use MDI's Jade version 7.5 software. The user also has access to International Center for Diffraction Data's Powder Diffraction File-2 database consisting of more than 163,000 inorganic entries and International Crystal Structure Data's crystal structure database with more than 93,000 entries