Abstract: Anhydrous magnesium carbonate crystal as a new inorganic functional material has attracted the attention of researchers. In this paper, anhydrous magnesium carbonate crystal was synthesized by using magnesium chloride as raw material and sodium carbonate as precipitant. And four different kinds of amino acids, named glycine, histidine, alanine, and L-aspartate, were used as additives to regulate the particle size and crystalline morphology of anhydrous magnesium carbonate crystals. The synthesized products were characterized by X-ray diffractometer, scanning electron microscope, and laser particle size analyzer, and the effects of different amino acids on the physical structure and morphology ofanhydrous magnesium carbonate powder were analyzed. The results show that the anhydrous magnesium carbonate regulated by histidine has highly degree of crystallinity, and the n(Mg²⁺)∶n(CO^2-₃) of the synthesized product is 1∶0.94. The purity of crystals regulated by L-aspartate is second. Partial magnesium carbonate hydroxides are grown in the crystals synthesized under the requlation of glycine and alanine. The crystalline morphologies of anhydrous magnesium carbonate crystals under the regulation of histidine, L-aspartate, glycine, and alanine are convex spherical triangular shape, ellipsoidal shape, spherical shape, and irregular shape, respectively. The particle size distribution of anhydrous magnesium carbonate crystals shows a trend of rising first and then oscillating down and trailing slightly particle size. These results provide reference to the bionic synthesis of anhydrous magnesium carbonate crystal.

Key words: amino acid, functional group, anhydrous magnesium carbonate, particle size distribution, hydrothermal synthesis, microstructure