X-ray diffraction of (Mg₀.₆,Fe₀.₄)SiO₃ glasses in diamond anvil cell under high pressure.

High-pressure X-ray diffraction measurements were performed on (Mg₀.₆,Fe₀.₄)SiO₃ glasses synthesized under oxidizing conditions, resulting in a higher Fe³⁺/Fe²⁺ ratio. The samples were loaded in membrane-driven Le Toullec-type diamond anvil cells (DACs) at the European Synchrotron Radiation Facility (ESRF) beamline ID27. Two datasets were acquired: one reaching pressures up to 110 GPa, and a second extending to 136 GPa. The DACs were equipped with Boehler–Almax single-crystal diamonds with culet sizes of 250 and 150 µm respectively, and pre-indented rhenium gaskets with laser-drilled sample chambers. A small gold piece (~5×5×5 µm³) served as a pressure calibrant.
Background diffraction patterns were collected prior to sample loading under identical experimental conditions to characterize scattering contributions from the gasket, diamonds, and pressure marker. X-ray diffraction measurements were conducted using a monochromatic 55,614.6 eV beam focused to 2×2 µm² with Kirkpatrick–Baez mirrors, and additional collimation with lead pinholes and a multichannel Soller slit system minimized parasitic scattering. Diffraction data from the glass sample were then collected in the same configuration, and the corresponding DAC background signal was subtracted to isolate the sample contribution, enabling accurate determination of structure factors S(Q) and pair distribution functions g(r).