Exploring the World of Carbonates: Mechanochemical Synthesis and In Situ X-ray Powder Diffraction (XRPD) Studies

Carbonates and carbonatite melts are integral to the geodynamics of the upper mantle and transition zone, influencing processes such as subduction, magma generation, mantle metasomatism, and diamond formation. The laboratory synthesis of many carbonate minerals is challenging due to the high pressures and temperatures required for their formation. Understanding the synthesis and reaction pathways of alkali and alkaline-earth metal carbonates is essential for advancing knowledge of their stability, transformations, geological relevance and potential applications. They exhibit diverse crystallographic structures and variable stability conditions, often necessitating specific environmental factors for their formation. Therefore, the development of alternative approaches is essential to enable controlled carbonate formation under more feasible laboratory conditions.¹

Mechanochemical synthesis presents a promising alternative, facilitating carbonate formation without the need for extreme pressures or temperatures. This technique utilizes high-energy ball milling to induce structural and physicochemical modifications, promoting chemical reactions through shear forces, or impact.² This study systematically investigates the mechanochemical synthesis of various carbonate systems, including K₂Ca(CO₃)₂ polymorphs³, dolomite, and sodium-rich natrocarbonatites such as nyerereite and pirssonite. Employing a Retsch MM400 shaker mill in combination with ex situ laboratory analysis and in situ XRPD, we explore reaction pathway, phase transitions, and crystallographic transformations to understand their phase stability and polymorphic behavior.^4,5

References

        1.Manning; C. E., et al. Carbon in Earth’s Interior. (2020).

        2.James; S. L., et. al. Chem. Soc. Rev. 41, 413 (2012).

        3.Kahlenberg, V., et al. RSC mechanochem, 2, 152, (2025).

        4.Rathmann;, T. et al. Rev. Sci. Instrum. 92, 114102 (2021).

        5.Weidenthaler, C. Crystals 12, 345 (2022).