Study on the effect of deuterium effect on the morphology of magnesium carbonate whiskers

Abstract

It is proposed that perturbations of several tens of ppm in the deuterium content of normal water may exert measurable influences on certain physical or chemical properties during aqueous-phase processes, a phenomenon termed the “deuterium effect”. Magnesium carbonate trihydrate whiskers (MgCO₃·3H₂O) were synthesized by the co-precipitation method using magnesium chloride and sodium carbonate solutions prepared with water containing 40–165 ppm deuterium at 30–70 °C, and the influence of the deuterium effect on product morphology was investigated. The products were characterized using XRD and SEM. The solubility during the reaction process was determined by titration. The results indicate that changes in deuterium content lead to significant variations in crystal morphology, transforming from predominantly hexagonal prisms to mainly tetragonal prisms with inclusions of irregular hexagonal prism structures. At the same temperature, the solubility of magnesium chloride and calcium carbonate in water with different deuterium contents varies by up to 22.24 % and 17.91 %, respectively, demonstrating the significant impact of the deuterium effect on water activity and crystallization products. Theoretical calculations using the Morphology and CASTEP modules revealed that a reduction in deuterium content causes the dominant exposed facet of MgCO₃·3H₂O to gradually change from the (212) plane to the (301) plane, leading to a transformation of the crystals from hexagonal to tetragonal prisms. The p orbital governs the stability of surface structures, and variations in deuterium content activate the density of states of the (212) plane, resulting in morphological changes. The theoretical results are consistent with the experimental observations.