Polymorphism and Phase Stability of Hydrated Magnesium Carbonate Nesquehonite MgCO₃·3H₂O: Negative Axial Compressibility and Thermal Expansion in a Cementitious Material.

ABSTRACT: The P-T phase diagram of the hydrated magnesium carbonate nesquehonite (MgCO₃·3H₂O) has not been reported in the literature. In this paper, we present a joint experimental and computational study of the phase stability and structural behavior of this cementitious material at high-pressure and high-temperature conditions using in situ single-crystal and synchrotron powder X-ray diffraction measurements in resistive-heated diamond anvil cells plus density functional theory calculations. Our results show that nesquehonite undergoes two pressure-induced phase transitions at 2.4 (HP1) and 4.0 GPa (HP2) at ambient temperature. We have found negative axial compressibility and thermal expansivity values, likely related to the directionality of the hydroge

SUBMITTER: Santamaria-Perez D 

PROVIDER: S-EPMC10854074 | biostudies-literature | 2024 Feb

REPOSITORIES: biostudies-literature