R2: Crystal structure, crystal chemistry, physical properties of minerals, crystal growth and applied mineralogy

[R2-05] Determination of the crystal structure of Earth’s constituent materials using in-house single-crystal X-ray diffraction measurements

[Presentation award entry]

*Shuhou MAITANI¹, Ryosuke Sinmyo¹, Takayuki Ishii², Kenji Yoza³ (1. Meiji University, 2. Institute for Planetary Materials, Okayama University, 3. Bruker Japan)

Keywords:single-crystal X-ray diffraction measurements

The crystal structures of Earth’s constituent materials are fundamental information to understand the physical and chemical properties of the interior of the solid Earth. While X-ray diffraction (XRD) measurement is a widely used technique to determine the crystal structures of materials, the single-crystal XRD measurement is the most powerful tool for crystal structure refinement. Recent studies have discovered many new crystal structures likely stable in the Earth’s deep interior by the single-crystal XRD measurement in diamond inclusions, shock veins in meteorites, and the recovered samples of high-pressure experiments. Here we performed ex-situ/in-situ single-crystal XRD measurements in the sample of high-pressure experiments using an advanced X-ray diffractometer (Bruker, D8 Venture). In the ex-situ measurement, we have measured Fe-, Al-bearing bridgmanite, and Fe₅O₆ iron oxide synthesized in a multi-anvil cell. Results showed that required measurements were completed in the single crystals with grain sizes of several 10 mm. The crystal structure refinement was successfully completed to reach an R factor of ~ 0.02. In the in-situ measurements, we measured ZrSiO₄ zircon under high pressure using Boehler-Almax type DAC with a wide aperture angle. Although the R factor was relatively higher than ex-situ measurements, crystal structure refinement succeeded under high pressure. The results of in-situ high-pressure single-crystal XRD indicated that the data quality is largely affected by the hydrostatic condition in the DAC sample and the precision of the sample position. In-house apparatus is effective for measurements with many samples since there is no time limitation compared to measurements at a synchrotron radiation facility. As a strong complement to the synchrotron facility, the advanced in-house single-crystal XRD measurement is expected to contribute to the studies in solid earth science via crystallographic analysis of the experimental, geological, and meteoritic samples.