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Improvements for high-pressure cell experiments using the latest single crystal laboratory systems

Winter 2013, Volume 29, No. 1
18-20
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Hiroyasu Sato

Pressure is one of the important parameters that define the structure and state of materials.

A high-pressure diamond anvil cell (DAC) is commonly used to measure the “in-situ analysis” of the structural change against pressure in the X-ray diffraction experiment. In a DAC experiment, it is necessary to enclose the sample in a space less than ~200 μm in diameter in order to apply high pressure.  The diameter of the X-ray beam should be smaller than the window of the DAC. There are thus three issues that make this experiment difficult to perform using a laboratory X-ray system. A small X-ray beam requires a large amount of collimation that significantly reduces flux, the window for the DAC absorbs X-rays, and finally the sample size has to be small and this reduces the diffraction intensities. Because of these restrictions, it is often believed that a synchrotron radiation X-ray source is needed to observe the X-ray diffraction in a DAC experiment.

However, recent changes in fundamental technologies related to X-ray sources and X-ray detectors allow us to obtain single crystal structures from crystals as small as a few microns in diameter with a laboratory system.  These new laboratory configurations improve the S/N of the DAC experiment to allow elucidation of structural information in the laboratory.

The combination of a microfocus rotating anode X-ray generator (MicroMax-007HF) and a multilayer focusing optic system (VariMax), produces a brilliance that is an order of magnitude better than that of the combination of the conventional rotating anode X-ray generator and graphite monochromator. This high brilliant X-ray source is integrated in the latest single crystal systems. The DAC experiment can easily be measured with such a system.
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