The observation of bulk superconductivity in Rhombohedral-ReO₃ under pressure

ReO₃ is a uniquely simple metallic oxide whose open perovskite framework makes it an ideal platform to reveal how oxygen-lattice geometry governs electronic and vibrational properties under pressure. Using a diamond-anvil cell, we combine electrical transport, quantitative dc susceptibility (with demagnetization correction), Raman spectroscopy, and synchrotron powder X-ray diffraction to construct a comprehensive phase diagram that links structure evolution to the emergence of bulk superconductivity. Raman and X-ray diffraction resolve a sequence of tilt-driven structural phases; the T_c(P) dome qualitatively aligns with the nearly hexagonally close-packed arrangement of oxygen layers within the rhombohedral phase (~20-40 GPa). Within this window, the magnetic shielding fraction exceeds 50% and is essentially pressure-independent. Near ~40 GPa it drops sharply to low values (even when resistivity retains a superconducting transition) unambiguously showing that bulk superconductivity is lost due to a structural/disorder change. These results show how pressure changes the oxygen-lattice structure and phonon spectrum, and how that changes the electronic structure in open-framework oxides.