Iron was shocked and probed at unprecedented time and strain rate to show all of its known structural types in 2.5 ns.

Synthetic mordenite is widely used as a molecular sieve, adsorbent, and catalyst. To enhance these functionalities, it is crucial to understand the ion-exchange properties and cation-exchange sites of the zeolite. In this study, we analyzed the structural changes in fully Cs-, Sr-, Cd-, and Pb-exchanged mordenite by using synchrotron X-ray powder diffraction under ambient conditions. Rietveld structure refinement revealed that the Cs⁺ cation is predominantly located near the 8-membered ring (8MR) due to its low electronegativity and hydration energy. In contrast, divalent cations such as Sr²⁺ and Cd²⁺ cations, with higher hydration energies compared to monovalent cations, are present as hydrated ions at the center of the 12-membered ring along the c-axis (12MRc). Pb²⁺ ions, due to their higher electronegativity than the framework atoms, exhibit a strong affinity for the electron cloud of framework oxygen atoms, which positions them close to the wall of the 12MRc. The observed differences in the locations of the extra-framework cations are attributed to electrostatic and hydration effects. Furthermore, the CO₂ adsorption capacity was assessed based on the type and site of exchangeable cations. The findings indicate that an increase in the CO₂ adsorption capacity correlates with the number of cations that can effectively interact with CO₂.

The geochemistry and mineralogy of Mn nodules offer crucial insights into the origins, environmental changes, and distribution of abyssal resources. However, the conventional laboratory X-ray diffractometer, usually employed for semi-quantitative analysis of mineral composition in Mn nodules, often fails to sufficiently detect minor phases due to beam flux limitations and high background signals. In this study, we investigated differences in manganate composition, even when comprising around 1% of the phase fraction, in two manganese nodules (KC-8 and KODOS-10) using high-resolution synchrotron X-ray diffraction. The Mn/Fe ratios of KC-8 and KODOS-10 were 1.32 and 6.24, respectively, indicating that KC-8 and KODOS-10 were predominantly formed in hydrogenetic and diagenetic environments. Both samples contained quartz, vernadite, buserite, and feldspar. Todorokite and illite were exclusively observed in KODOS-10. In KC-8, the phase fractions of vernadite and buserite among manganates ranged from 94(5)%–100(4)% and 6(1)%–0%, respectively. However, in KODOS-10, the fractions of vernadite, buserite, and todorokite ranged from 47(1)%–56(2)%, 33.6(4)%–40.1(3)%, and 10(3)%–16.3(8)%, respectively.

High-pressure synchrotron X-ray powder diffraction studies of smectite group minerals (beidellite, montmorillonite, and nontronite) reveal comparative volumetric changes in the presence of different fluids, as pressure transmitting media (PTM) of silicone oil and distilled water for anhydrous and hydrous environments at room temperature. Using silicone oil PTM, all minerals show gradual contraction of unit-cell volumes and atomistic interplane distances. They, however, show abrupt collapse near 1.0 GPa under distilled water conditions due to hydrostatic to quasi-hydrostatic environmental changes of water PTM around samples concomitant with the transition from liquid to ICE-VI and ICE-VII. The degrees of volume contractions of beidellite, montmorillonite, and nontronite up to ca. 3 GPa are ca. 6.6%, 8.9%, and 7.5% with bulk moduli of ca. 38(1) GPa, 31(2) GPa, and 26(1) GPa under silicone oil pressure, whereas 13(1) GPa, 13(2) GPa, and 17(2) GPa, and 17(1) GPa, 20(1) GPa, and 21(1) GPa under hydrostatic and quasi-hydrostatic environments before and after 1.50 GPa, respectively.

Manganese (Mn) nodules are deep-sea mineral resources that contain critical elements for modern industries, such as nickel (Ni), cobalt (Co), and copper (Cu). As a result, extensive global research has been conducted on the exploration and formation mechanisms of Mn nodules. However, studies investigating the correlation between manganate minerals and critical elements, as well as the deep-sea environment represented by these mineral phases, have been limited. Here, we show the significance of phase transformations in manganate minerals within Mn nodules, in relation to deep-sea formation environments and the geochemical behavior of Ni, Co, and Cu, using basic statistical analysis, machine learning, and hydrothermal experiments. The statistical analysis and machine learning models revealed that the trace amounts of Ni, Co, and Cu exhibit a positive correlation with vernadite, a dominant manganate mineral in Mn nodules. Additionally, hydrothermal experiments demonstrated that under suboxic conditions at temperatures between 120°C and 150°C, Mn nodules undergo mineral phase transformations, forming various minerals, including todorokite, Mn ferrite, fluorapatite, hematite, and goethite. During these transformations, Ni, Co, and Cu were incorporated into the mineral structures of todorokite, fluorapatite, and Mn ferrite, respectively. Therefore, the mineral phases within Mn nodules serve as key indicators not only for understanding their formation environment but also for tracking changes in the geochemical behavior of Ni, Co, and Cu. Furthermore, our methodological approach demonstrates to many researchers how correlations between materials can be validated and utilized using statistical analysis and machine learning techniques.