Magnesium Impurities Decide the Structure of Calcium Carbonate Hemihydrate
Julie Aufort, Raffaella Demichelis
Abstract
High Resolution Image Download MS PowerPoint Slide The new and recently detected hydromorph of calcium carbonate, hemihydrate, has been analyzed via both first-principles and classical theoretical methods. The orientation of the water molecules, that remained unclear in the experiment, has been determined. A structure with symmetry higher than that originally proposed results from geometry optimization ( Pbcn, space group number 60) of the pure phase. The introduction of magnesium impurities causes a distortion in the unit cell, which assumes the monoclinic arrangement ( P 2 1 / c ) originally proposed. This is consistent with the magnesium-rich experimental conditions.
Topics & Concepts
MagnesiumHemihydrateImpurityCalcium carbonateMonoclinic crystal systemCrystallographyGroup (periodic table)ChemistryCrystal structureMoleculeCalciumMineralogyInorganic chemistryMaterials scienceGypsumMetallurgyOrganic chemistryCalcium Carbonate Crystallization and InhibitionMagnetic and Electromagnetic EffectsMethane Hydrates and Related Phenomena