ブックタイトル日本結晶学会誌Vol61No3

概要

日本結晶学会誌Vol61No3

HPCAT: A Static Compression Science Sector at the Advance Photon SourceFig.3（a）An example of time-resolved HP-XRD setup with DECTRIS Eiger 1M detector at 16-ID-B general purpose table（top）and pressure-response of sample along with the rate variation of pressure increase（bottom）;（b）an illustrationofon-linelaser-heatinginstrumentationcoupledwithHP-XRDataseparatetable（middle）,theschematicofopticalsystem（top）and a picture of the sample stage in-operando（bottom）.（adapted from Ref. 8 and Ref.9, respectively）comprehensive crystallographic information regardingelastic and deformative responses of crystals to externalforces, electron-density topology, bonding natures, as wellas phase identities under static compression conditions.The experiments can be conducted for various forms ofcrystals, including polycrystalline powders, nanocrystalline,non-crystalline substances, and single crystals, andreadily combined with resistive heating, laser-heating, andcryocooling techniques to bring the materials of interest to anextreme condition in the P-T space.16-ID-B experimental hutch is configured with twoindependent experimental setups separated on two tables：one for general-purpose micro-diffraction experiments 8）and the other for those coupled with in-situ laser heating, 9）respectively（Fig.3）. Monochromatic（18～60 keV）micro-focused beam（3μm×6μm or 1μm×2μm）with2×10 11～1×10 12 photons/sec flux on to the sample isused for advanced high-pressure diffraction experimentsincluding time-resolved diffraction（Fig.3a）, scanningX-ray diffraction imaging, 10）,11）low-Z element diffractionexperiment（e.g., solid water diffraction）, 12）and multi-Mbardiffraction experiment. 13）The on-line laser-heating coupledwith diamond anvil cell is one of the most demanding highpressuretechniques to realize extreme conditions of sampleespecially for the temperature. Its application has enablednumerous breakthrough sciences, e.g., discovery of newoxidation state of iron under deep-Earth conditions. 11）Theexperimental tables are highly versatile to adapt varioussample environments, including cryo-cooling and resistiveheating, in addition to the on-line laser-heating. Theapplication of cryocooling technique enabled a discovery ofnear-room-temperature, high-T c superconducting materials日本結晶学会誌第61巻第3号（2019）recently. 14）4．16-BM-D：High-pressure general diffractionand absorption spectroscopy beamline16-BM-D beamline is dedicated to powder and singlecrystal X-ray diffraction experiments with micro-focusedbeam（4.5×4.5μm 2）for the samples under high-pressurein diamond anvil cells（DACs）. The X-ray energy is chosenusing Si 111 double-crystal monochromator（DCM）inpseudo-channel-cut geometry; the high-energy resolution（Δλ/λ＝2×10－4）and the fixed exit design of themonochromator allows the beamline to be used for energyscanningX-ray absorption spectroscopy（XAS）. 15）By usingan X-ray transparent gasket for the sample assembly, e.g.,beryllium gasket, inserting pneumatically controlled ionchambermount whenever necessary to monitor the incidentand transmitted X-ray intensities as transmitted perpendicularto the opaquer diamond anvils, the XRD measurement can bereadily combined with XAS measurements. Two pre-definedgeometries, one for XRD with a large area detector（e.g.,MAR345 Image Plate）at a fixed distance and the other forXAS with ion-chambers, are used for combined XRD-XASmeasurement, or each technique can be used independently（Fig.4）. The beam focusing is done by a pair of table-topKB mirrors（320 mm long, 1.8 mrad incident angle, Pt,Rh, and bare Si stripes to be chosen for each purposes）,which focus the X-ray beam achromatically thus the focusedbeam positions at the sample maintains over a large rangeof selected energies（6～45 keV）. The XAS technique iscomplementary to XRD to determine a delicate variation inlocal coordination structure and electronic band propertiessubject to high-pressure. 16）The beamline is highly versatile165