We have developed a new type of experimental setup utilizing a multi-anvil large volume press and designed for simultaneous measurements of structure-sensitive thermophysical properties (diffraction, electrical resistivity, viscosity). This multi-probe capability was tested on iron alloys at 2 GPa and up to 1750 K. Phase transitions as detected by X-ray diffraction patterns are clearly associated with changes in the electrical response of the samples. In Fe-S liquids, viscosity measurements in the molten state indicate an increase in viscosity with increasing the amount of alloying agent. A correlation between electrical resistivity and viscosity from our data and previous works is observed. This multi-probe measurement capability improves the detection of solid-state transformations and solid-melt transitions, relates structural and electrical properties of geomaterials, and allows constraining the mobility of melts using viscosity data. This new setup advances research about melt distribution and mobility at conditions relevant to planetary interiors.

A. Pommier, K. Leinenweber, H. Pirotte, T. Yu & Y. Wang (2020) In situ electrical resistivity and viscosity measurements of iron alloys under pressure using synchrotron X-ray radiography, High Pressure Research, DOI: 10.1080/08957959.2020.1865343 abstract

Beamline configuration for diffraction measurements (XRD spectra), electrical measurements (using the impedance spectrometer), and falling sphere viscosity measurements (using the CCD camera) in the 1000-ton Large Volume Press at 13-ID-D. In the X-ray radiography mode, the slits are moved out of the X-ray path and the transmitted X-ray produces a visible image, which is recorded by the CCD camera. In the diffraction mode, the beam size of incident X-ray is reduced by the slits to 100 × 100 μm and the diffracted X-ray is collected on the GE solid-state detector (SSD)