X-ray fluorescence holography under high-pressure conditions

This study reports the first application of X-ray fluorescence holography (XFH) under high-pressure conditions. We integrated XFH with a diamond anvil cell to investigate the local structure around Sr atoms in single-crystal SrTiO₃ under high pressure. By utilizing nano-polycrystalline diamond anvils and a yttrium filter, we effectively eliminated significant background noise from both the anvils and the gasket. This optimized experimental configuration enabled the measurement of Sr Kα holograms of the SrTiO₃ sample at pressures up to 13.3 GPa. The variation of lattice constants with pressure was calculated by the shifts of Kossel lines, and real-space images of the atomic structures were reconstructed from the Sr Kα holograms at different pressures. This work successfully demonstrates the feasibility of employing XFH under high-pressure conditions as a novel method for visualizing pressure-induced changes in the three-dimensional local structure around the specified element.