Crystalline polymeric phases of sulphur dioxide

Year: 2025

Authors: Zhang H.C., Dalladay-Simpson P., Capitani F., Ji C., Zhang L., Santoro M., Gorelli F.A., Martonbk R.

Autors Affiliation: Ctr High Pressure Sci & Technol Adv Res, Shanghai, Peoples R China; LOrme Merisiers, SOLEIL, Dept 128, St Aubin, France; Shanghai Adv Res Phys Sci SHARPS, Shanghai, Peoples R China; Consiglio Nazl Ric CNR INO, Ist Nazl Ott, Sesto Fiorentino, Italy; European Lab Non Linear Spect LENS, Sesto Fiorentino, Italy; Comenius Univ, Fac Math Phys & Informat, Dept Expt Phys, Bratislava, Slovakia.

Abstract: SO2 is a molecule of significant industrial and geochemical importance, known for its role in sulphuric acid production and its natural occurrence in volcanic processes. Recent studies have revealed pressure-induced amorphisation and the formation of polymeric amorphous phases in SO2, behaviours analogous to those observed in other fundamental molecular systems such as CO2, N2, and CS2. Here, we identify a mixture of polymeric SO2 phases, with space groups Ama2 (Z = 2) and Pmc21 (Z = 8), the latter a homologue of gamma-SeO2, as the crystalline parents of the previously reported threefold-coordinated amorphous SO2 observed above 25 GPa. These phases were characterized using a combination of advanced synthesis and refined high-pressure loading techniques, alongside x-ray diffraction, Raman, and infrared spectroscopy. Structural assignments were further supported by numerical predictions of candidate crystal structures. Notably, the Ama2 and gamma-SeO2-like phases exhibit in the pressure region 20-60 GPa the lowest and near-degenerate enthalpies, Ama2 being stable below 25 GPa and gamma-SeO2-like above 25 GPa. Both phases feature distinctive W-shaped polymeric units, a structural motif identified long ago at ambient pressure in the rare-mineral Downeyite (SeO2), but the stacking of chains is different and pressure-dependent.

Journal/Review: COMMUNICATIONS CHEMISTRY

Volume: 8 (1)      Pages from: 374-1  to: 374-9

More Information: This work was supported by the Slovak Research and Development Agency (Contracts nos. APVV-19-0371 and APVV-23-0515) and the National Natural Science Foundation of China (NSFC grant number W2532012). We acknowledge MAX IV Laboratory for time on Beamline NanoMAX under Proposal 20210122. Research conducted at MAX IV, a Swedish national user facility, is supported by the Swedish Research council under contract 2018-07152, the Swedish Governmental Agency for Innovation Systems under contract 2018-04969, and Formas under contract 2019-02496. We also acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of beam time at the ID27 beam line. M. S. acknowledges HPSTAR for having allowed him as a Visiting Scientist during part of his research on SO2.
KeyWords: High-pressure; Nitrogen; Transformations; Transition; State; Co
DOI: 10.1038/s42004-025-01757-y