Solution-mediated transformation is crucial in a wide variety of fields such as the formation of materials and minerals. However, no one knows the universal strategy for the growth of crystals formed by solution-mediated transformation. Here, we present the growth of norsethite [BaMg(CO3)2] by adding NH4NO3, and discuss the key to overcoming the difficulties of the solution-mediated transformation. Norsethite is poorly-soluble, and appears through witherite [BaCO3]. The solubilities of norsethite and witherite in NH4NO3 solutions were ~35 and ~45 times higher than those in the absence of NH4NO3, respectively. At 90℃, the growth rate of norsethite in NH4NO3 solutions was ~17 times higher than that in NH4NO3-free solutions. Finally, we succeeded in synthesizing bulky norsethite of 150 μm size only in one month, utilizing 1M NH4NO3 solutions of 90℃. We explained the appearance of large norsethite by adding NH4NO3, considering that norsethite dominantly consumes the solute compared with witherite.
